The $500 500SL Offroadster

[Beater400E]

Also, if you have engine oil leaking from the cam solenoids so the lower edge of the cap has oil on it... that is another potential cause of the issues. Read my post here, note there was liquid inside the caps during a hot, dry, Boise summer and the liquid was not water.

Yeah, that's definitely on my radar. I think I already re-sealed the solenoids on this car, but maybe not. I'll check the solenoids and cam seals while I'm in there. Pretty sure I also sprayed the insulators with a high quality lacquer clear coat the last time I was in there too, but I'll check that too.

I'm pretty sure one of those things will be the issue. It's not rocket surgery. Just need to be methodical going through it.

 

[Beater400E]

I just got my hands on an ASR diff housing that I have no real use for. I haven't gotten around to installing the locked diff in the 500SL. If I swap the pinion over to the ASR housing and then install the locked carrier with the ASR output flanges, I think I can swap that in without having to swap to outer hubs with outboard wheel speed sensors. I'll have to get the pinion depth set up correctly, but I can do that.

Sort of a bummer to have all the parts to try out the outboard speed sensor conversion, but then never actually complete it, but oh well.

 

[R129 UK]

This is without question the cheapest R129 SL I have ever seen if true:

 

[Beater400E]

It's finally time to get some work done on the 500SL in preparation for Gambler events for this year. Last time I drove the car the ignition system was acting oily. Pretty sure the cam solenoids are leaky. There are a number of other things that need work, but I need to start by just getting it running reliably again.

I tried to start it to pull it into the shop and discovered the battery was dead. Not a great start. It's been sitting for probably 2 months, so I guess I shouldn't be too surprised. I tossed a different battery in it and tried to start it and the starter did nothing. Fiddled with the shifter, but still nothing.

I ended up jumping 12 volts to the starter trigger wire under the hood and it cranked over and started. Pulled it into the shop and now I get to troubleshoot that.

My understanding is that this could be the NSS, K38, or ignition switch, or possibly the wiring. The lower engine harness is brand new, and worked fine to trigger the starter, so I'm sure it's not there.

The car has never given me any trouble with the starter, which makes me think the ignition switch and NSS are unlikely. Everything was perfect 2 months ago, and now nothing.

I checked fuses, and they all look fine. I replaced fuse #8 under the hood, which I believe is the one that feeds power to K38. Nothing.

I'll probably search around here on the forum for a bit before I break out the WIS. If anyone has any tips, I'm all ears.

 

[Beater400E]

Starting to make a little progress on this. I eventually found the k38 relay and discovered I'm getting no power from fuse 8. Fuse 8 has 12v on both sides of the fuse, so presumably I have an open circuit between the fuse block and the relay. No idea how that could have happened while the car was parked, but I guess I'll start pulling things apart to inspect.

 

[Beater400E]

Ok, scratch that. The power is getting to the relay. I had tested with the key off like a dummy. The issue is actually that I have no ground signal from the ATA module.

 

[Beater400E]

I don't know what's really going on there. I assume the anti-theft alarm module is unhappy with something and preventing the car from starting. I checked power and grounds to the module. That all looks fine. I swapped in a different module I had from a 91 300SL. Not sure whether that would have been truly compatible, but it did plug right in. Still nothing.

I don't ever want the alarm to go off for any reason, and I don't think the immobilizer is really helping me any. I think I'm going to just bypass it. Looks like I should be able to jump from pin 3 to pin 1 on the relay harness and it should take care of it. I've seen the common figure 8 wire solution, but that makes me a little concerned about a possible loose or corroded connection there, so I'll probably do something similar, but a but more substantial.

 

[Beater400E]

Made a little copper bridge and then soldered it in place. My solder job looked terrible, so no photos of that.

Installed it and the car fired right up. Good enough. I'll slap everything back together and start in on the real work.

 

[Beater400E]

Got my 3.69 diff finished up. As a reminder, this is the diff that came out of the 91 300SL I parted out a while back. I modified it to accept a Spartan mechanical locker meant for a Chrysler 8.25" diff. I finished the machining ages ago, but needed to blow everything apart to do final cleaning and then assembly with new seals and the correct axle stub shafts and driveshaft yoke.

Got that all completed without issue. One interesting dilemma was the stub axle retention. It might have been possible to sneak the stock retaining clips in, but it would have been extremely difficult. I elected instead to use wire snap rings, just like you'd use with a Wavetrac or Quaife. I can't think of any reason that would be a problem.

To install, I'll need to swap in 036/034+ASR/129.066 axle shafts. I'm judging the length based on the fact that a 129.066 uses the same diff housing and rear hub setup, and has the thick axle shafts.

Of course, the offroadster has ASR, and my 3.69 diff is from a car without ASR, so the plan is to swap the rear hubs/knuckles from a later R129 that had the sensors in the knuckles. I picked up a pair of new tone rings for a W210, which should be able to be pressed onto the axles I'll be using.

I'm pretty confident that will all work. I have all the parts already, so hopefully I'll get to try it soon.

Before that though, I need to do cam seals and solenoids. That's next.

 

[Beater400E]

More progress. Pulled the distributors apart. Everything is actually quite clean. Cam seals are brand new. I must have done that already. The solenoids were seeping just a bit, so I'll swap in another set I had previously resealed.

The only issue I found was the left side insulator. I had cleaned the insulators and sprayed them with clearcoat when I first put the car together. One of the insulators is losing clearcoat inside and out right at what would have been the bottom of the distributor.



The car has done a bunch of water crossings in the last year, so I'm sure there has been water in the distributors at some point. I'm guessing that's part of the problem. Best guess is that water got inside, providing a path for spark to short to ground. That arcing may have attacked the clearcoat? Not sure. But now there's loose clearcoat inside the distributor, possibly including some orange dust from the insulator itself. There's also some dirt in there, probably from all the dusty roads and mud this car sees.

I'll clean everything up and put it together with resealed solenoids. Not sure exactly what I'll do with the insulators. I'd like to find a robust solution to seal the insulators and prevent these issues in the future. I could just buy new ones, but this car is as much about homebrew R&D as anything.

 

[Beater400E]

This is what I landed on for the insulators. I cleaned up a set and then got some Gardner Bender LTS-400 aerosol spray liquid electrical tape. I sprayed in about 4 coats to get good coverage on both sides. I did mask off the edges where the cap mates up so I dont have any problems there.

Just finishing up reassembly now. We'll see how well it works. Obviously it'll be hard to know until I put several thousand miles on it... unless it fails early on. Some day I'll update and share how well it seems to perform.

 

[Beater400E]

Oh hey. Look what I just found.

 

[gsxr]

Oh hey. Look what I just found.

Another Bremi rotor failure. Very odd... wonder what caused that. Stick with OE (Doduco) or Bosch!

 

[Beater400E]

I rummaged around to find all my other rotors to see if there were other good options. Found a nearly new pair of Bremi, so those are going in.

I also popped the caps and rotors off the 119.960 engine I have sitting here.

It had one Bosch and one Doduco. Check out the condition.

The Bosch:



and the Doduco:



I'll probably pick up a fresh set of Bosch rotors at some point.

 

[gsxr]

I also popped the caps and rotors off the 119.960 engine I have sitting here.

It had one Bosch and one Doduco. Check out the condition.

Those look like HIGH mile rotors!

 

[Beater400E]

Back together and running great. Next job: swap in late style front lower control arms that won't rub the brake rotors. As a reminder, I installed 334 mm front and 300 mm rear brakes on this car last year and have had issues with the front brakes hitting the control arms at certain steering/suspension angles ever since. Finally going to fix that.

 

[Beater400E]

More progress. Pretty boring stuff most of the week. I installed a set of external emergency strobe lights in the car while I was waiting for other parts to come in. This is a silly thing, but the whole car is silly.




The exterior strobes are activated by a little switch panel I made that sits just behind the convertible top switch. It allows me to turn the system on and off, and also to switch between various different strobe patterns. It also has 8 LEDs in the switch panel that display the strobe pattern. The strobes are there mostly just for fun, but also because we do a ton of roadside trash cleanup and emergency strobes might actually be handy at times to alert other drivers of our presence.

Anywho, got that done and I'm back on the front end. My steering damper was leaking so I rummaged through my hoard and found a good one and tossed that in. Looking now at my front brakes. Since the old style control arms had gouged up the old rotors pretty badly I ordered a new set of rotors and pads. As I began the install I discovered this.



I'd never seen that before. According to Dave's info it's a factory piece on the last couple years of 334mm (Silver Arrow-ish) brakes.

If I understand correctly, best bet is to just reinstall it and slap the new pads on top, right? Should I lube it up first with caliper grease? I don't know what most people do, but I usually do a thin layer of grease across the entire back side of the pad, as well as the sliding pins. I'm inclined to lube up both sides of the anti-vibration insert thing before installing. Thoughts?

 

[gsxr]

I'd never seen that before. According to Dave's info it's a factory piece on the last couple years of 334mm (Silver Arrow-ish) brakes.

Correct!

If I understand correctly, best bet is to just reinstall it and slap the new pads on top, right? Should I lube it up first with caliper grease? I don't know what most people do, but I usually do a thin layer of grease across the entire back side of the pad, as well as the sliding pins. I'm inclined to lube up both sides of the anti-vibration insert thing before installing. Thoughts?

Also correct - keep the damping plate. You could apply a bit of caliper grease if desired, or wait and see if there's any squealing. I'd only apply grease to the face which contacts the pads.

 

[Beater400E]

Got the front end finished up and moved on to the rear. The rear is pretty involved, as you'd imagine.

A brief overview of everything I'm doing as part of that project:

Remove the stock 2.65 rear diff and install the 3.69 from my 300SL with the Jeep locker and 129.066 axles with new tone rings pressed on, 2000 SL500 rear knuckles and outer wheel speed sensors.

While I have it all apart I'm doing both driveshaft isolator rings, as well as the diff mounts in the crossmember and a new set of rear lower outer control arm bushings in the new knuckles. I'm also replacing the transmission tailshaft seal and transmission shifter bushings while I'm in there.

The disassembly is mostly complete at this point. I've swapped the wheel speed sensors over on the chassis side and confirmed they do plug right in. One minor issue is that the later outboard wheel speed sensors use a thicker bushing on the sensor wire that won't simply clip into the plastic routing clips the car currently has.



I have a 95 SL500 parts car, so I'm hoping the plastic cable routing clips on that car will work for this. Guessing they will.

Aside from that, it all looks good so far. It's a lot of work, but it looks doable.

 

[Beater400E]

Wow those diff mount bushings are a pain. I managed to just collapse the outer bushing shell with an air hammer, but pressing the new one in is tricky. I've machined some tools to press the new bushings in, but the 7/16 grade 5 bolt I was using to pull the bushing in snapped in half before the bushing was all the way in.

I'll have some grade 8 bolts delivered tomorrow. Hopefully that will get it done. I also noticed I have a minor fuel leak dribbling down the fuel supply hose from the strainer. Guess I'll have to deal with that while I'm in here too.

 

[Beater400E]

Ok, I got the fuel line problem sorted. The strainer o ring was flat. Installed a new one and hopefully that does it. I got a couple grade 8 bolts in and was able to finish installing the new bushings for the diff mounts.

Next problem. I bolted the new diff in, which required a much shorter bolt for the front mount, but I actually had the original bolt that diff used in its donor car, so easy fix there.

And now a bigger issue. Driveshaft length. The new diff is about 22mm shorter from the front mount to the driveshaft flange. So I need the driveshaft to be 22mm longer. I rummaged through my pile of Mercedes driveshafts and I do not have a good option. My 95 donor has its driveshaft, but I'm not sure how long it is. I believe the 95 uses the later style diff, which I think is closer in size to the 3.69 diff, so I might get lucky. I'll do a little online research before I actually bring that car into the shop though. I have to move like 5 cars to get that one out right now.

 

[gsxr]

93-up R129's with M119 have the bigger "reinforced" diff, which apparently are longer and use the shorter driveshaft.

Assuming you installed an early non-reinforced diff... I think the driveshaft from any 90-92 500SL (129.066) may be the correct length? Wasn't there an early 129 at the Jungle?

 

[Beater400E]

93-up R129's with M119 have the bigger "reinforced" diff, which apparently are longer and use the shorter driveshaft.

Assuming you installed an early non-reinforced diff... I think the driveshaft from any 90-92 500SL (129.066) may be the correct length? Wasn't there an early 129 at the Jungle?

Yeah, quick research says the 95 is marginally shorter than the 93, so no help there. The 129.066 is the correct length. There was one at the Jungle when I was out there a month or so ago. Guess I'll go see if it's still there.

 

[Beater400E]

Guess I'll go see if it's still there.

The rear half was still there, so I snagged it. The front half had been cut. Hopefully the front half is the same on both.

 

[Beater400E]

Junk yard driveshaft for the win. The rear half is exactly what I needed.

 

[Beater400E]

More progress. Almost ready to test drive.

Got the driveshaft installed. That went perfectly. I cleaned up the axles and tapped on new tone rings. I was a little concerned about how easy it was to tap one of them on so I decided to add a dozen or so little dabs of cyanoacrylate glue to each as extra insurance.

The earlier knuckles used pressed in sleeve bushings on two of the control arms. The upper one then uses a weird bolt with two diameters. I can't fathom why it was done that way. The later knuckles did away with the reducing bushings, and just used larger diameter bolts. When I installed the knuckles, I just knocked the reducing bushings out of the control arms and used the larger bolts. In the process of knocking one of the reducing bushings out I managed to break one of the actual bushings in one of my control arms. Good thing I have a parts car. I yanked the arm off my parts car and used that.

Removing the plastic retainers for the outer wheel speed sensors from my 95 donor car proved to be a no-go. The retainers that are attached to the control arms just press onto pins, and the old plastic was a bit too brittle to be extracted intact. I probably could have just swapped the entire lower control arm, but I'd already broken one of the retainers, so too late.

I ended up just zip tying the speed sensor wires in place instead. If I cared more I could probably track down a good set of factory style retainers or control arms, but there would be another minor issue anyway. The later cars only use brake wear sensors on one side, meaning there isn't an appropriate brake wear sensor wire for the right side that has the integrated clip for the wheel speed sensor. That's an incredibly minor detail, but one I found interesting.

Anyway, I got the rear end all buttoned up last night. With the wheels on I was able to do a static test of the mechanical locker setup in the new diff. It works exactly as it should. I didn't have any concerns about that. I machined everything myself and set the tolerances the same as if the locker was in a Jeep diff, so it would have been surprising if there was a problem. Just nice to confirm it's good.

I have a few details to finish up before I go drive it. My "good used" steering damper that I installed a few days ago is now leaking terribly, so I ordered a new one. I also need to finish my custom rear control arm sensors for the automatic roll bar deployment. Hopefully I'll get those done today and take the car for a test drive.

 

[Beater400E]

Got out and made the first test drive. It's pretty good so far. There are a few little issues. I had a rubbing spring clip on the right front brake caliper that was making a bunch of noise. The suspension is pretty unsettled in general. Desperately needs an alignment after all that.

The locker works, and is less intrusive than I'd feared. I'm very pleased with the outcome there. The 3.69 gears completely transformed the car. It wants to accelerate hard at all times. My fuel economy is going to suck. More because I'll be deliberately throwing rooster tails everywhere I go off road than anything.

The brakes are super spongy. I'm going to go through and bleed the whole system. I also have a tire rubbing on the right rear wheel opening. I'm sure my alignment has shifted just enough to make that a new problem. I'll clearance the body a bit more there.

Once all that is addressed I'll take it out and run it again. This is the "integration testing" stage.

 

[Beater400E]

Got those last few details sorted. The brake spring clip was an easy fix. Just needed to snap it back over the sliding pin correctly.

The tire rub was solved by trimming the wheel well. I may need to do some welding and grinding in the rear wheel wells. The trimming has separated the wheel well from the quarter panel a bit. I need to join them back up and maybe seam seal that area.

I bled all 4 corners of the brakes, but they were still spongy. Turns out there was air in the ABS pump. Once I bled the air from the pump the brakes were way better.

I also noticed one of my fog lights wasn't working. I traced it back to the bulb out relay. Popped it open and found a few cracked solder joints on the board. Resoldered the joints and we're back in business.

The car is still great off road. It just has more low end grunt and more traction now. ASR and ABS do work with the new outboard wheel speed sensors, so consider that confirmed.

It's harder to break the tires free, as you'd imagine with a locker. It's doable, but with both rear tires spinning the tail end wants to swing out a lot more. It's driftable for sure.

I've been thinking about installing a drift brake setup in the car and honestly with the locker and gears in place, it kind of needs it. If I'm drifting it around and want to suddenly pull it back straight, it's tough with the automatic transmission. I'm not ruling out potentially swapping in a manual transmission at some point, but I think a drift brake is a better next step.

I looked at installing a second set of calipers in the rear and having an independent hydraulic handbrake, but there really isn't room for a second caliper. I could pass the rear brake hydraulic lines through a pair of master cylinders on the way to the rear. I'd have to use two if I want to retain ABS, which I do.

I don't know if I'll actually do it. If I do it probably won't be for a while.

It'll get an alignment later this week and then probably a little upholstery work. The driver's seat is in pretty sad shape. I'm not worried about esthetics, but I would like it if the seat doesn't fully disintegrate. I also have a set of headrests and headrest motor gears to install. The driver's side is floppy and neither side is able to be raised at this point.

I still need to install the roll bar control arm sensors. Never got around to that today.

In the near future I need to rebuild the last few hydraulic cylinders for the top. The ones I didn't do last year are now leaking. I also need to replace the soft top windows. The rear window split in half last year.

I'd also like to install a Yellow Box. The speedometer read low last year with the 31 inch tires and 2.65 gears. Now with 3.69 gears, it reads high. The Yellow Box will fix that.

It could use new speakers. The stock ones can't handle any amount of bass without breaking up. Not sure what my best option is there.

I'm also considering doing an electric radiator fan swap. I did a W220 S55 PWM fan swap in my 400E and it's fantastic. I'd like to do the same in this car, but I'd like to see if I can figure out a less expensive option for the PWM controller. The Micro Autonomations setup works well, but I have to think there's a cheaper way.

Most of that isn't urgent though. It's totally usable as it is right now. Just in time for Gambler 500 season. I have a bunch of trips planned over the summer.

 

[gsxr]

I bled all 4 corners of the brakes, but they were still spongy. Turns out there was air in the ABS pump. Once I bled the air from the pump the brakes were way better.

You mean the "SP" port on the ASR pump, right? This is part of the standard bleed procedure.

ASR and ABS do work with the new outboard wheel speed sensors, so consider that confirmed.

Excellent! On paper I had suspected this would work fine, glad you confirmed.

I've been thinking about installing a drift brake setup ... I don't know if I'll actually do it. If I do it probably won't be for a while.

Drift brake. That would be amazeballs.

It'll get an alignment later this week

Where do you plan to get the car aligned? Also, have you looked into Gyraline? I'm still kicking myself that I didn't buy this when it was on sale during BFCM for like $99.

I'm also considering doing an electric radiator fan swap. I did a W220 S55 PWM fan swap in my 400E and it's fantastic. I'd like to do the same in this car, but I'd like to see if I can figure out a less expensive option for the PWM controller. The Micro Autonomations setup works well, but I have to think there's a cheaper way.

AFAIK there is not a lower-cost solution that works as well as Micro Autonomations. Were you able to connect the Micro Autonomations box to the factory 4-pin temp sensor? Or did you need to use an aftermarket temp sensor dedicated to the MA box? On the bright side, you should be able to get a mid-aughts 600/800W fan from the Jungle for cheap. I really need to get this figured out on an 034/036 and start converting my cars to electric. Wish I had known about this when I still lived near the Jungle.

 

[Beater400E]

You mean the "SP" port on the ASR pump, right? This is part of the standard bleed procedure.

Yup. I hadn't expected to have air in there so hadn't bothered with it before. I won't make that mistake again.

Excellent! On paper I had suspected this would work fine, glad you confirmed.

Yeah, it all made sense on paper, but I haven't heard of anyone actually doing it before. Fortunately it went pretty much as expected. I love the way these cars are like Lego. So many different configurations are possible with factory parts.

Where do you plan to get the car aligned? Also, have you looked into Gyraline? I'm still kicking myself that I didn't buy this when it was on sale during BFCM for like $99.

No, I hadn't even heard of Gyraline before. Very interesting. I might have to check into that. For this car, it usually just goes to a tire shop. My 400E goes to the dealer, but this car gets beat up and modified so much that Gyraline might make the most sense.

AFAIK there is not a lower-cost solution that works as well as Micro Autonomations. Were you able to connect the Micro Autonomations box to the factory 4-pin temp sensor? Or did you need to use an aftermarket temp sensor dedicated to the MA box? On the bright side, you should be able to get a mid-aughts 600/800W fan from the Jungle for cheap. I really need to get this figured out on an 034/036 and start converting my cars to electric. Wish I had known about this when I still lived near the Jungle.

I'm actually thinking of trying to make my own. I mean, HOW HARD CAN IT BE, right? I'm sure it'll prove to be better to buy the MA box again, but I've wanted to play around with Arduino a bit, so I might experiment a bit to see what I can come up with on my own.

For my 400E I just drilled and tapped my upper water neck for an aftermarket temp sensor. Any time I run across one of the big fans at the Jungle I snag it. They only want $15 for them, so I might be kind of hoarding them. I think there might be a couple at the State Street yard right now. I'll see if I can snag you one.

I have a few other tips and tricks if you're wanting to go that route. Wiring the heavy gauge wires is an interesting one. I wanted to do it with proper heavy gauge wire and with no splices. That meant that MA's off the shelf option would not work. I ended up sourcing the connector components and building that wiring from scratch.

Once I figure out how I want to handle the PWM controls I might see about putting together a thread on the electric fan conversions. My 400E turned out so nice, and with some additional R&D I think I can probably nail down a recipe anyone can follow to convert to an electric fan.

 

[gsxr]

No, I hadn't even heard of Gyraline before. Very interesting. I might have to check into that. For this car, it usually just goes to a tire shop. My 400E goes to the dealer, but this car gets beat up and modified so much that Gyraline might make the most sense.

I want to get that eventually. From what I could tell, it may be quite fiddly, but once you get the hang of it, the results should be pretty decent. Note that it relies on measuring the angle of a body panel (e.g., doors) to figure out the vehicle center line. If the car is bent from a previous wreck, that could cause problems.

I'm actually thinking of trying to make my own. I mean, HOW HARD CAN IT BE, right? I'm sure it'll prove to be better to buy the MA box again, but I've wanted to play around with Arduino a bit, so I might experiment a bit to see what I can come up with on my own.

Have you read Roncallo's adventures with creating his own controller? It's pretty neat stuff. Recent update is here. Previous updates are buried in that 66-page, 1300-post thread.

For my 400E I just drilled and tapped my upper water neck for an aftermarket temp sensor.

Ah, got it. I am hoping to piggyback on to a factory sensor for a clean appearance, although for an 034 I'd be less picky.

Any time I run across one of the big fans at the Jungle I snag it. They only want $15 for them, so I might be kind of hoarding them. I think there might be a couple at the State Street yard right now. I'll see if I can snag you one.

Cool! I'm specifically looking for the 204- fans... p/n 204-500-02-93 which I think is used on most all 204 chassis, plus some R172 SLK's, and 207/212/218's... although I expect the latter aren't showing up at the Jungle yet (too new). This fan seems to need the least modification to stuff into the 034/036. You probably have more room to play with in the R129.

I have a few other tips and tricks if you're wanting to go that route. Wiring the heavy gauge wires is an interesting one. I wanted to do it with proper heavy gauge wire and with no splices. That meant that MA's off the shelf option would not work. I ended up sourcing the connector components and building that wiring from scratch.

I wanted to use the factory connector, and splice as needed... but if I could obtain the new OE connectors and create a fresh harness, that would be ideal. Is this what you did? I wonder if the 204- fan uses the same connector as your Big Boy AMG fan.

Once I figure out how I want to handle the PWM controls I might see about putting together a thread on the electric fan conversions. My 400E turned out so nice, and with some additional R&D I think I can probably nail down a recipe anyone can follow to convert to an electric fan.

I really think that using the OE fans with the OE PWM controller is absolutely the best way to go. At least we know the MA controller works, but isn't cheap. A lower-cost solution would be nice but I expect many people wouldn't mind paying for MA to ditch the fiddly mechanical clutch.

 

[Beater400E]

Have you read Roncallo's adventures with creating his own controller? It's pretty neat stuff. Recent update is here. Previous updates are buried in that 66-page, 1300-post thread.

I hadn't seen that before. That's interesting. I'll have to make time to read through that one.

Cool! I'm specifically looking for the 204- fans... p/n 204-500-02-93 which I think is used on most all 204 chassis, plus some R172 SLK's, and 207/212/218's... although I expect the latter aren't showing up at the Jungle yet (too new). This fan seems to need the least modification to stuff into the 034/036. You probably have more room to play with in the R129.

What is it about the W204 fan that makes it easier to fit in the 034/036 cars? Is it thinner? I'll definitely have to grab one now just to compare. The R129 does have a lot more room.

Ah, got it. I am hoping to piggyback on to a factory sensor for a clean appearance, although for an 034 I'd be less picky.

I'm sure that could be done too. Maybe I'll look into that for the R129.

I wanted to use the factory connector, and splice as needed... but if I could obtain the new OE connectors and create a fresh harness, that would be ideal. Is this what you did? I wonder if the 204- fan uses the same connector as your Big Boy AMG fan.

I'm pretty sure they'll both use the same connector. That exact connector is used on a number of PWM fans from Mercedes, BMW, General Motors, and others. I tracked down the plastic housing, as well as all the needed crimp terminals and seals and just build a new harness from scratch. It really deserves its own thread. There was s a fair bit of research required to figure it all out, but once you have all the info, it's not hard to replicate. I actually just acquired 10 full sets of connector components just so I can perfect the process.

I really think that using the OE fans with the OE PWM controller is absolutely the best way to go.

Are you saying there's an OE PWM controller option? I thought the OE controllers were built into ECMs, and there was no standalone option.

I expect many people wouldn't mind paying for MA to ditch the fiddly mechanical clutch.

I'm certain you're right about that. My motivation isn't as much about trying to save money as it is to educate myself more about electronic controls and design. For me, this hobby is really about learning new skills. I own all kinds of machining and fabrication tools and equipment, but have zero training or professional experience with any of that.

I've learned just by jumping in head first and figuring it out. The first few attempts are almost always a losing venture. Way more time and money goes into the solution by trying to DIY it, but I develop skills that make that task easier for myself or others in the future, and those new skills often help to solve other similar problems I might encounter later. My cars have tons of custom machined and fabricated parts now that would not have been an option if I'd had to pay someone else to develop and manufacture them all.

This just strikes me as an opportunity to develop some new skills, so I'll probably see what I can figure out.

 

[R129 UK]

@Beater400E I just want to say I truly admire your efforts and the time you take to write up what you are doing (and why) with this car.

Your skills, knowledge and experience are far greater than mine and a lot of what you write goes right over my head but you seem very competent at everything you are doing and you appear to really enjoy it.

What you accomplish in a few hours would take me weeks...or maybe until the end of time

 

[gsxr]

What is it about the W204 fan that makes it easier to fit in the 034/036 cars? Is it thinner? I'll definitely have to grab one now just to compare. The R129 does have a lot more room.

I believe the 204 fan dimensions most closely match the 034/036 radiator core. Bigger fans do things like poke above the top of the radiator (like your AMG fan), which I'd prefer to avoid. There may be other suitable fans similar to the 204 but without Jungle access, I haven't been able to survey what's available from other chassis.

I'm pretty sure they'll both use the same connector. That exact connector is used on a number of PWM fans from Mercedes, BMW, General Motors, and others. I tracked down the plastic housing, as well as all the needed crimp terminals and seals and just build a new harness from scratch. It really deserves its own thread. There was s a fair bit of research required to figure it all out, but once you have all the info, it's not hard to replicate. I actually just acquired 10 full sets of connector components just so I can perfect the process.

This would be an awesome thread to document what's needed!

Are you saying there's an OE PWM controller option? I thought the OE controllers were built into ECMs, and there was no standalone option.

Yes, sorry - I meant the OE fan, with built-in PWM controller, is the best way to go. TFNT used an external PWM controller but I don't like that for multiple reasons, and there's no advantage. The external controller is, IMO, only useful with a fan that lacks integrated PWM control. We just need a low-voltage signal generator like the MA box, or what Roncallo created.

This just strikes me as an opportunity to develop some new skills, so I'll probably see what I can figure out.

Got it. I think Roncallo's thread will be right up your alley. I wish all the controller posts weren't scattered throughout that long thread.

 

[Beater400E]

@Beater400E I just want to say I truly admire your efforts and the time you take to write up what you are doing (and why) with this car.

Your skills, knowledge and experience are far greater than mine and a lot of what you write goes right over my head but you seem very competent at everything you are doing and you appear to really enjoy it.

What you accomplish in a few hours would take me weeks...or maybe until the end of time

Thanks, I appreciate that. Remember though, I cheat. I have a well-equipped shop with a lift and tons of info here on the forum, and on Dave's site.

 

[Beater400E]

I believe the 204 fan dimensions most closely match the 034/036 radiator core. Bigger fans do things like poke above the top of the radiator (like your AMG fan), which I'd prefer to avoid.

Got it. Yeah. I actually liked that fact with mine. The fan blade diameter is as large as possible to move as much air as possible. The shroud is actually the same size as the radiator core, but the fan stretches above it a bit.

In this picture you can see what I mean.



That said, a smaller fan would probably be more than adequate and might be a bit more subtle.

I meant the OE fan, with built-in PWM controller, is the best way to go.

Is there an OE fan with a built-in PWM controller?

 

[gsxr]

That said, a smaller fan would probably be more than adequate and might be a bit more subtle.

Exactly. I'd like something that could almost pass for a factory installation.

Is there an OE fan with a built-in PWM controller?

I might be using the wrong terminology and causing confusion here - oooops. I believe all the OE Mercedes fans include integrated PWM controllers. But they are normally controlled by the Bosch ME ECU. Without the factory ECU signal, we need to provide an appropriate speed signal based on engine temp and AC compressor engagement. That's where we use the MA or Roncallo-style signal generator.

 

[Beater400E]

I might be using the wrong terminology and causing confusion here - oooops. I believe all the OE Mercedes fans include integrated PWM controllers. But they are normally controlled by the Bosch ME ECU. Without the factory ECU signal, we need to provide an appropriate speed signal based on engine temp and AC compressor engagement. That's where we use the MA or Roncallo-style signal generator.

So this is where I'm a little confused too. What I don't know is what the controller on the fan really does, and what the ECU or MA signal generator really does.

I know that the fan-mounted controller input has two heavy gauge wires, and two light gauge wires. Obviously the heavy gauge wires are the high amp fan load power input. The two light gauge wires are some kind of signal. I imagined that the fan-mounted controller was essentially just a big solid state relay, and not really a "controller" per se. I assumed the rapid on/off pulses are generated by the ECU, and sent to the fan-mounted relay where the high amp circuit is then triggered.

Is that your understanding as well, or do I have it wrong? I haven't really done any investigation on this yet. This is all just an educated guess.

 

[gsxr]

My understanding is that the integrated PWM controller allows infinite fan speeds. This box does all the hard work, managing the high-current power to the fan motor.

Google offers this explanation: "A DC PWM (Pulse Width Modulation) controller works by rapidly switching a DC voltage on and off, varying the amount of time it's on (the "duty cycle") to effectively change the average voltage delivered to the motor, and therefore its speed. This method allows for precise control over motor speed without wasting energy through methods like variable resistors."

I believe the input signal (from Bosch ECU, or MA, or Roncallo) is relatively simple, possibly just a varying DC voltage? The controller then interprets this signal voltage into a target fan speed.

 

[Beater400E]

I finally finished up my roll bar control arm sensors. For those who are not familiar, the early R129 cars use effectively a pair of limit switches on the rear lower control arms to identify when the rear suspension is at full extension. If it detects the suspension is at full extension while certain other conditions are present, like a tilt beyond a certain number of degrees, the car will decide it might be in danger of rolling over, so it will automatically deploy the roll bar. It does this by hydraulically retracting a retaining pin and allowing a spring loaded mechanism to be released which fully extends the roll bar in a fraction of a second.

The roll bar can be lowered again easily using a switch on the dash. It's not like a single use safety feature like an air bag. It can be deployed and reset indefinitely. That makes it kind of a fun game to see how many times I can get the roll bar to deploy while racing around off road. My record is 11 in one day. It certainly would have been more but on the 11th deployment I hit a rock and ripped both sensors off the car. If the car does not detect the sensors, the roll bar deploys and cannot be retracted.

The problem is that the control arm sensors sit on the bottom edge of the control arms and are plastic. They are a little delicate and extremely vulnerable.

Last year I destroyed two full sets of sensors off road. At about $200 per set for used sensors, that kind of sucks. So I decided to build my own.

I started by machining some solid steel housings to accept an off the shelf microswitch, which I mounted inside. I then made a solid steel arm that gets activated when the control arm is at full extension and acts on the microswitch. The key is that the arm is prevented from over extending and damaging the microswitch, so even if it gets hit, it will still work unless the solid steel arm gets badly bent.

If it does get damaged, I should be able to straighten or replace components fairly easily, and the microswitches are less than $5 each.



With that out of the way, I do have a few new problems that need attention.

First, the soft top does not work. For this I'm sure I'll just need to go through the system methodically to discover the problem. It's not magic. It'll either be a hydraulic issue or an electrical issue, and the WIS has detailed diagnostic procedures. I did notice a couple of leaking hydraulic cylinders in the rear. Last year I rebuilt a half dozen or so in the front half of the car. I didn't mess with the rear at that time though. Now the rears are leaking, so I'll probably just rebuild the rest while I'm going through it.

The second issue is a clunk somewhere in the drive train. My first guess is motor mounts. I installed new mounts last year, but they were cheap no name mounts. They don't appear to be leaking, but when I hammer the throttle there is a noticeable clunk as soon as the torque hits. This happens before the transmission gets a chance to downshift, so it's not related to trans shifting. It's a mount or bushing somewhere.

I'll do some more investigation this weekend. I suspect the 3.69 rear gears are essentially allowing a greater torque multiplication through the drive train, which applies an equal and opposite force back into the motor mounts and they are not able to adequately damp that movement.

If that is the case I'll probably look at either filling a set if mounts with urethane, or maybe just fabricating some custom mounts. For some of the custom 4x4s and hot rods I've built in the past I've just used generic rubber bushings and DOM tube for custom motor mounts. They wouldn't be as buttery smooth as factory hydraulic mounts, but they should be able to handle much more abuse.

I'm not sure what else could be causing the clunk. I've checked over all the bushings everywhere in the car and can't find any that look even a little questionable.

The last issue is a vibration under hard acceleration. It feels like maybe driveshaft. I installed new flex joints at both ends, so it's not likely to be those. The center bearing felt pretty good. The rubber bearing mount was a little more compliant than I would have expected, but not torn or anything. The u joint was a little notchy, but basically every MB u joint I've come across has been like that. Since the u joint never really flexes it will get stiff. None of the driveshaft components seem like a smoking gun. Not really sure what to do there.

 

[R129 UK]

Do you have SDS?

I have sone documentation I created which captured the status of the soft top on a correctly functioning car at both the open and closed states. My later car possibly has 1 more cylinder than yours but I can’t remember when it changed from 11 to 12 or whatever it was.

 

[Beater400E]

Do you have SDS?

I have sone documentation I created which captured the status of the soft top on a correctly functioning car at both the open and closed states. My later car possibly has 1 more cylinder than yours but I can’t remember when it changed from 11 to 12 or whatever it was.

I don't have SDS, but I don't think I'll need it for this. I suspect this will be pretty simple. The pump is working. I can raise and lower the roll bar. The switches are working. The issue is probably going to be a limit switch or a hydraulic cylinder.

With my luck it'll end up being the control module. I had two good spares, but I ended up selling them both. I figured if I ever need one down the road I can buy one or pay to have mine repaired.

Incidentally, that's basically what I've been doing with my entire parts hoard. I have an ebay store where I've listed the majority of my spare parts. Although it's possible that I might end up selling something that I'll need later, the amount of money I bring in more than pays for any parts I might need to buy back.

Really, the eBay store is just how I justify continuing to dump time and money into my cars, and to buy parts cars. If I don't track my labor, this hobby is making me money rather than costing money.

I've sold maybe $6,000-7,000 worth of parts in the last 6 months, which has more than covered the cost of all the parts and parts cars I've purchased over that time.

In reality, it's just a matter of keeping my wife happy. She wasn't thrilled with the amount of money I'd been spending on parts and upgrades on my cars, so I just made it pay for itself.

Anyway, I'll do some troubleshooting this weekend. I'm probably going to run to a couple junk yards this morning. I want to grab a couple radiator fans, and hopefully some hood hinges for another forum member. When I get back I'll dive in.

 

[gsxr]

The last issue is a vibration under hard acceleration. It feels like maybe driveshaft. I installed new flex joints at both ends, so it's not likely to be those. The center bearing felt pretty good. The rubber bearing mount was a little more compliant than I would have expected, but not torn or anything. The u joint was a little notchy, but basically every MB u joint I've come across has been like that. Since the u joint never really flexes it will get stiff. None of the driveshaft components seem like a smoking gun. Not really sure what to do there.

This is a hybrid driveshaft, right? Could be it needs to be balanced. I was never able to find a local shop in Boise capable of balancing a 2-pc shaft but maybe there's a new game in town. Otherwise you can send it out to one of the handful of places that balance these. Allegedly they should be balanced with the new flex discs bolted on.

Another possibility is the driveshaft angle is off. This is hard to measure since you need to get under the car with the full weight on the suspension. MB's of this vintage seem abnormally sensitive to the angles, which can be adjusted via shims at the front diff mount, and (if needed) custom shims at the trans mount. Roncallo went through this in this epic thread linked above, including some on-car videos showing the center support oscillating when accelerating under load. I forget if he ever had his prop shafts balanced though.

 

[R129 UK]

The issue is probably going to be a limit switch or a hydraulic cylinder.

Yes, that is quite likely, probably a switch or at least I would start there.

Anyway, I was tidying up my files so here they are just in case they are of any use to you or if anyone else needs them in the future.

 

[Beater400E]

This is a hybrid driveshaft, right?

If by hybrid driveshaft you mean it's composed of parts from multiple other driveshafts, then yes. The front half is the original 93. The rear half is the 92 from Jalopy Jungle.

I'm pretty sure it actually had this same issue before the rear half was swapped, but the 3.69 gears made it a lot more noticeable.

Another possibility is the driveshaft angle is off. This is hard to measure since you need to get under the car with the full weight on the suspension. MB's of this vintage seem abnormally sensitive to the angles, which can be adjusted via shims at the front diff mount, and (if needed) custom shims at the trans mount.

That's definitely possible. I have lowered the rear subframe as part of my suspension lift. To attempt to keep everything aligned I made custom spacers for the center support bearings and the trans crossmember. I calculated the heights of those spacers by determining the height of the crossmember drop, and the distance from the motor mounts, since they effectively are the pivot point around which the entire power train was pivoted. From there some simple math determined the ideal heights of the spacers.

It's definitely possible that my angles aren't perfect. I may try mounting a camera on the chassis in a few places and driving it so I can see what it's doing.

 

[Beater400E]

I hit the junk yard today and brought home four electric fans. I got a W220, a W203, a W211, and an R230 fan. There was a W204 fan, but it was slightly damaged so I just took some measurements and left it. I might go back later and snag it.

I plan to start a new thread discussing electric fan conversion topics. I'll provide a bunch of pictures and measurements of the various fans, and a bunch of details on controlling them and installing them in our cars.

This afternoon I did a little testing to try to figure out what might be causing the vibration I've been feeling. The drive shaft carrier rubber bushing really seems extra compliant. I don't see any tears in it, but I can flex it up and down pretty easily. I'll probably see about replacing that. I'd like to replace the u joint as well, but I have no idea where to source parts for that or what the proper procedure would be given the factory joint is staked in place.

 

[TerryA]

@Beater400E,
You’ve made a marriage between two different drive shaft parts. You might need to get your driveshaft rebalanced. I had this done a longtime ago on my 190SL. It made a huge difference on my 190SL.
I live in SoCal, I have no idea where you could get this done in Boise, Idaho.

 

[gsxr]

This afternoon I did a little testing to try to figure out what might be causing the vibration I've been feeling. The drive shaft carrier rubber bushing really seems extra compliant. I don't see any tears in it, but I can flex it up and down pretty easily. I'll probably see about replacing that. I'd like to replace the u joint as well, but I have no idea where to source parts for that or what the proper procedure would be given the factory joint is staked in place.

The rubber support donut may be fine... same with the bearing, and U-joint. I really think the issue is either balance, or incorrect angles.

This post from roncallo's thread shows what a driveshaft angle issue may look like. Pretty sure his center support + bearing were new? Video link below. He only adjusted angles (via shims) to improve this.
https://www.benzworld.org/posts/18207957/

This post shows how he custom mounted a GoPro to monitor the driveshaft:

https://www.benzworld.org/posts/17626020/

 

[Beater400E]

This post from roncallo's thread shows what a driveshaft angle issue may look like.

That does look a lot like what I'm feeling. You mentioned the need to get the car on its suspension to take a proper measurement. Would loading the suspension make a difference? I would think as long as the trans mount and diff mounts are in good shape it shouldn't really matter. I'll try to get some measurements today.

 

[Beater400E]

@Beater400E,
You’ve made a marriage between two different drive shaft parts. You might need to get your driveshaft rebalanced. I had this done a longtime ago on my 190SL. It made a huge difference on my 190SL.
I live in SoCal, I have no idea where you could get this done in Boise, Idaho.

I'm not completely ruling that out, but the symptom is most pronounced at lower speeds and high driveshaft loads. To me that suggests an issue with compliance, or possibly angle like Dave suggested, rather than balance. I would expect a balance issue to be more prominent at higher speeds. In my case it smooths out as speeds increase.