The $500 500SL Offroadster

[Beater400E]

Pretty sure I know what I did wrong. I adjusted the throttle linkage. That was not the issue. Before I installed the W140 ETA I opened it up to inspect and clean it. I'm fairly certain when I reinstalled the right side cover, with the M16/1 actuator, I didn't get the lever arm properly engaged with the pot arm.

Working on pulled it back out to fix that now.

 

[Beater400E]

Ok, got that ETA yanked back out. Sure enough, I had assembled it wrong. Got that fixed and back together and now I have a throttle again.

Just need to throw a few things back together and I'll get it out for a test drive.

 

[Beater400E]

No dice. Same exact issue with the W140 ETA.

Not sure what to try next. I could swap in a different LH to see if that makes any difference. Any other modules I should try swapping? I have spares of everything.

Also, my charging system is definitely no better. I saw as low as 11.8 volts idling with all the lights on. Highest number I can get is 13.8 with everything off and running at 2500+ RPMs. I'll probably try swapping in a different alternator next.

 

[Beater400E]

Ok, I figured it out. It was the LH module. I had a 92 WOT module in there with the upgraded EPROM. It had been fine for probably close to a year, and then it just started doing this surging thing. I swapped in a different 92 WOT LH and the problem is 100% gone.

I don't know whether the issue is the EPROM or the module itself. I may swap the stock EPROM back in and try the first module again. I'd like to isolate it to either the EPROM or the module if I can.

 

[Beater400E]

For the record, LH module that was acting up was a 014-545-18-32 with a date of 92M04. The capacitors were replaced last year, and the EPROM was upgraded.

The module that is not acting up is a 012-545-62-32. It has a stock EPROM, and I don't think I've replaced the capacitors in this one yet.

Just throwing those data points out there for the next guy.

 

[Beater400E]

I swapped the stock EPROM back into the 014 module and took it for a drive. The issue is back. So it appears it was not the EPROM. Looks like the LH module is misbehaving. That's a bummer. Being that this is a WOT module, I'd really like to fix it. I can swap the other one in to resolve the issue on this car, but I only have these two WOT modules and the second was supposed to go in my 400E when I eventually get around to 5.0 swapping it.

Does anyone have any thoughts on what might be wrong with it the module?

I also swapped in a different alternator to see if my voltage would be any different. It seems to be maybe a tiny bit better, but still not great. I did swap my new regulator over to this other alternator as well, so I guess if the new regulator is a dud I could be fighting that.

At idle with the lights off I'm at 13.0 volts. Turn all the lights on and it drops to 12.0. I think the biggest part of the issue could just be that at idle RPM the output is too low to support all the silly lights. As soon as the RPMs rise above 1000, my voltage rises to 13.5-13.7 or so, even with all the lights on. It never goes higher than 13.8.

My battery is pretty discharged right now, so that could be a factor. I'll get it charged back up overnight and test again tomorrow.

I previously had a smaller diameter pulley on my alternator. I think that was causing belt slip at times, but I wonder if the smaller diameter pulley might actually help with this. It would spin at a higher RPM, and might solve the issue.

The obvious answer is to just not idle for extended periods with all the lights on, but this car does a lot of roadside cleanup and rescue/repair stuff in dusty and/or dark conditions, so I really like having all the lights for safety.

 

[Beater400E]

I may try grabbing a 180 amp alternator from the junk yard and see if that helps with the charging system. Looks like some late M113 cars had a 180 amp alternator that might work.

 

[gsxr]

Not sure about the LH mystery. Have you tried resetting adaptation to mean values on the "bad" module to see if that changes anything?

Alternator could be a dud regulator, but first fully charge the battery and see if the issue remains. I use the standard/stock pulley from all M119's with 6-rib pulleys. I wasn't aware of a smaller one, only larger.

I'm also not aware of any alternator larger than 150A that works with our cars - however, I never seriously researched this. If a 180A unit is available, that would definitely be interesting!

 

[Beater400E]

Not sure about the LH mystery. Have you tried resetting adaptation to mean values on the "bad" module to see if that changes anything?

I completely forgot that was a thing. I have not. I'll do that. Just clear all LH codes, and then "clear" code 1, right?

Alternator could be a dud regulator, but first fully charge the battery and see if the issue remains. I use the standard/stock pulley from all M119's with 6-rib pulleys. I wasn't aware of a smaller one, only larger.

I probably need to test my battery and make sure it's actually healthy. I only discovered the smaller pulley thing because mine had a smaller pulley on it for some reason. I had belt slip issues during WOT 1-2 upshifts until I swapped a standard pulley back in. I'm confident the smaller pulley would help, but I really don't want to bring back that belt slip issue.

I'm also not aware of any alternator larger than 150A that works with our cars - however, I never seriously researched this. If a 180A unit is available, that would definitely be interesting!

I was curious whether a higher output option existed, so I did a little digging. I know the 150 amp from an M113 fits, so I thought maybe some other M113 might have a higher output option. I figured if anything would need a higher output alternator it would be an AMG S Class. So I looked up a 2003 S55, and sure enough, it uses a 180 amp alternator. In pictures, it looks like the same frame as the 150 amp. Checking the compatibility of that 180 amp alternator shows it is used on all M113K cars, as well as the 2006-2007 ML500 and R500. So that's what I'll be looking for.

 

[gsxr]

I completely forgot that was a thing. I have not. I'll do that. Just clear all LH codes, and then "clear" code 1, right?

Correct! With SDS (HHT-Win) you can view the actual values, which can be helpful as you can see if adaptation is maxed out either rich or lean (usually it's lean, 0.8xxx).

I probably need to test my battery and make sure it's actually healthy. I only discovered the smaller pulley thing because mine had a smaller pulley on it for some reason. I had belt slip issues during WOT 1-2 upshifts until I swapped a standard pulley back in. I'm confident the smaller pulley would help, but I really don't want to bring back that belt slip issue.

Interesting! If you know the diameter of either one, I'm curious what they are. I had not measured these in the past, nor photographed the differences.

I was curious whether a higher output option existed, so I did a little digging. I know the 150 amp from an M113 fits, so I thought maybe some other M113 might have a higher output option. I figured if anything would need a higher output alternator it would be an AMG S Class. So I looked up a 2003 S55, and sure enough, it uses a 180 amp alternator. In pictures, it looks like the same frame as the 150 amp. Checking the compatibility of that 180 amp alternator shows it is used on all M113K cars, as well as the 2006-2007 ML500 and R500. So that's what I'll be looking for.

The voltage regulator changed on the newer cars, around approximately MY 2000. I never experimented to see if the new VR would work with our older cars. The connector on the back is different. If this does work, that would be awesome.

I believe the newer alternators generally all look like the ones shown below. Note that only 1 wire may be used of the 2-pole VR connector.

 

[Beater400E]

The voltage regulator changed on the newer cars, around approximately MY 2000. I never experimented to see if the new VR would work with our older cars. The connector on the back is different. If this does work, that would be awesome.

I believe the newer alternators generally all look like the ones shown below. Note that only 1 wire may be used of the 2-pole VR connector.

Yeah, I just assumed there was a way to make it work. My biggest concern was whether it would even bolt up. Looks like it should, so I'll give it a shot if I can get my hands on one.

I forgot to mention, another thing I'm going to try is LED bulbs. I usually don't like retrofit LED bulbs in place of factory incandescent bulbs. They never perform the way you'd hope. The thing about the rally lights on this car though is that I don't really use them to light the road ahead. They're mostly just cosmetic, and also add a factor of safety by making the car more visible. They can still do that with LED bulbs.

If I replace the 55w fog light bulbs and the 100w driving light bulbs with LEDs, I expect that will make a big difference. I also have 100w headlight bulbs in the factory housings. I may try some retrofit LED bulbs there as well. I'm less willing to sacrifice real performance there, as you'd imagine, so if I'm not happy with LED headlight bulbs, the 100 watt Hella bulbs might stay.

I expect all those LED bulbs would significantly reduce the demand on the alternator.

 

[Beater400E]

Well damn. Resetting adaptation fixed it.

 

[Beater400E]

MAF strainers had been NLA for a while but are back in stock at dealers. I just picked up 4 from Laredo.

 

[gsxr]

MAF strainers had been NLA for a while but are back in stock at dealers. I just picked up 4 from Laredo.

Nice! Wish these weren't $30 each... sheesh...

000-090-01-45 - Parts Kit, Oil Screen MB Parts Source

Factory Direct Parts Kit, Oil Screen (900145) For Your

www.mbpartsource.com

 

[Beater400E]

Nice! Wish these weren't $30 each... sheesh...

Yeah, still beats the $50 each that everyone else seems to want though. I have a few MAFs on the shelf that I might try to sell. They all have damaged strainers though, so this will solve that.

 

[gsxr]

I have a couple with damaged strainers too. Always nervous about them getting damaged in shipping though. Looks like yours arrived in perfect shape.

 

[Beater400E]

I have a couple with damaged strainers too. Always nervous about them getting damaged in shipping though. Looks like yours arrived in perfect shape.

They did. Laredo stacked them together and then double bagged them before putting them in the box. Pretty decent effort. They arrived in perfect condition.

 

[Beater400E]

The junk yard did not have the 180 amp alternator, so that gets to remain a mystery for now.

I replaced my headlight, driving light, and fog light bulbs with LEDs. Between that and fully charging the battery, I think it's probably good now. Driving with the lights on I'm seeing between 13.7 and 14.0 volts. It never goes above 14.0. That seems to be where the voltage regulator wants to be.

Idling, in gear with absolutely everything turned on high I'm around 12.6-12.7 volts. In park it's 12.9-13.0 volts.

The biggest power user appears to be the climate control blower motor. Idling with the lights on and the AC on with the fan on "4", I'm around 13.0 volts. Reduce the blower to "1", and I jump straight to 13.9. Turning the AC off takes me back up to 14.0, even with the lights on.

The lights were definitely a factor, but that blower motor is eating a ton of power too. It's not blowing a fuse, so I assume it's probably healthy, so probably not much I can do about it.

I also finally replaced the breather hoses from the ETA to the valve cover, as well as the ETA boot and MAF strainer with brand new OE parts. Since I had the ETA out numerous times, the original hose and boot did not survive. They were all rock hard. I had tossed some Uro junk in there short term, but now that everything is sorted the OE parts will keep it happy.

 

[gsxr]

Nice work on the ETA+PCV refresh! The OE parts will last a long time.

Any chance you have a DC clamp-style ammeter to measure current draw?

Sounds like the HVAC blower is the item which pushes the draw beyond what the alternator can provide at idle. The blower likely pulls 20-30A on high, assuming it's similar to the 124 blower. If you are already consuming ±100A with everything else on, adding the blower on max could exceed idle output, which would cause the voltage to drop below mid-13's.

 

[Beater400E]

Ok, this is funny. My cabin air filter was full of dirt. I pulled it out and knocked a bunch out and then blew it out with compressed air. Reinstalled it, and now no matter what I do my volts don't drop below 14.0. I'll order a few new filters and plan to replace it regularly since dusty offroad driving is what this car does.

So that was a key part of my root cause. My charging system appeared weak because of a clogged cabin air filter causing the HVAC blower to draw more amps than normal.

Bonus, my HVAC moves noticeably more air now.

 

[Beater400E]

I finally ordered a Yellow Box for the Offroadster. I installed it and... nothing. My speedometer doesn't work.

I've confirmed it is powering on and I know I have it set up correctly. I have one in my 400E and I love it. The speedometer works when I install the jumper plug to put the configuration back to stock. I think I may actually have a defective Yellow Box.

I could try swapping the box from the 400E in to confirm, but I'm pretty confident in my testing.

I've emailed Yellow Box support to ask for help or a replacement. I'm sure they'll take care of me. I'll report back once we figure it out.

 

[Beater400E]

Well, I'm less confident in my testing now. Which is to say, after a little back and forth with Yellow Box support, I finally just yanked the box out of my 400E and plugged it into my SL and... no luck. It doesn't work.

Tried plugging the new Yellow Box into my 400E, and it works fine. So I do not have a defective Yellow Box.

Trying to figure out what I did wrong.

 

[Beater400E]

I eventually got the Yellow Box working. Long story short, I spliced a ground wire into the brown/white leg of the VSS, and then it worked. I guess without that ground the sensor was supplying alternating current on both legs, and the Yellow Box can't work with that. I don't know. I'm just happy it's working.

 

[Beater400E]

New problems. Just did about 600 miles through northern Nevada, which is way more beautiful than I expected by the way. The car did great aside from the rear window gaining another huge split. I really need to replace those windows at some point.

Now that the car is home, I went to put it on the lift to inspect, but when I started it i had a battery light and my voltage was reading 11.8 volts while running. So my alternator is not charging for some reason. My suspicion is the new regulator failed. I've done zero troubleshooting at this point though.

Once the car went up on the lift I discovered a new oil leak. It looks like a possible rear main seal, which does not sound fun to deal with. It's a minor leak. It hasn't dropped on my floor. I just see the oil on the bottom of the bellhousing.

 

[Beater400E]

Well this is getting interesting.

I'm not going to worry about the rear main seal for now. As I was poking around at that I noticed that the left hand side starter cutout in the transmission bellhousing has no cover plate. Is that normal? I don't recall ever seeing a cover plate there. I feel like maybe there should be one. I run this car through dust and dirt and mud and water a lot. I wouldn't be surprised if the rear main seal leak was caused largely by dirt and debris getting into the seal and causing premature wear. Just a theory, but if a cover plate should be there I'll need to try to find one.

That's not the interesting thing though. I have trips planned for the next 3 weekends in a row, which will see me traveling around 4,000 miles total. I leave for the first one in 3 days. I still don't have a charging system that works, and I just picked up a few new items I'd like to install before I leave. And I have to work my day job in the mean time.

The charging issue is likely the alternator. I ordered 5 voltage regulators, just so I can have spares handy in the future. They won't be here in time, so what I'll probably do is yank the 143 amp alternator off my 95 500SL for now. I want to keep that car driveable until it's ready to be fully dismantled, so I'll need to put an alternator back on it. I'll probably toss one of my 120 amp alternators on there for that.

I was hoping to find another junk yard 150 amp alternator, so I searched the local junk yards and discovered that another 129 recently landed at one of my local yards. I ran out there after work today to have a look. It's a 94 SL500. Looks like it was in really nice shape before the crash that landed it in the yard. I pulled a bunch of parts to add to the hoard. In the process, I yanked the hard top off and manually deployed the soft top.

Hallelujah. The soft top is brand new. Someone just had the soft top replaced with what looks like an OE quality top. The windows are crystal clear and flexible. The top is black, unlike my original blue, but that doesn't concern me at all. A black top on a dark blue car looks fine to me, and I'm not really concerned with aesthetics. I just want to have a roof that will keep the weather out and the air conditioning in.

I got the entire top assembly for $85.

I also just picked up a new stereo for the car. I know purists will cry that I'm going to remove a working factory stereo and install some generic aftermarket thing, but I'm aware I can sell the stock stereo for more than an aftermarket head unit will cost, and this is a low buck car that needs hands free calling.

I picked up a decent Kenwood head unit, and then dug a set of Infinity component speakers out of storage. One of the R129 cars I parted out last year had some nice speakers in the doors and I'd saved them.

I hooked all this stuff up on the bench and tested it out with my phone and everything works nicely. I really needed to add hands free calling to this car. I do long road trips in this car a lot and the absence of quality hands free calling has been a pain point.

So that's the plan. Or at least the wish list. I need to fix the charging system, replace the soft top, and install a new stereo system in the next couple days before I leave on my next journey. I don't know if I'll have time to do it all, but I'm going to try.

 

[gsxr]

Yup - there should be a cover plate over the unused starter cutout. Fabulous score on the soft top, btw!

I am curious how long the cheap VR's last. Bosch production switched to Taiwan a number of years ago and I vaguely recall some people reporting relatively short life spans vs the older VR's made in India or UK.

 

[Beater400E]

How much vegetation is supposed to be in an alternator?

 

[Beater400E]

The regulator brushes were stuck. This happens when dirt or mud gets in behind them. I've had this happen several times on my Jeep. It's what I expected.

 

[gsxr]

The regulator brushes were stuck. This happens when dirt or mud gets in behind them. I've had this happen several times on my Jeep. It's what I expected.

Interesting. There's a Range Rover 150A alternator (BOSCH AL0809X) that appears to fit this application, which has sealed (or, partly sealed) VR brushes. I wonder if that would be better for off-roading.

 

[Beater400E]

Interesting. There's a Range Rover 150A alternator (BOSCH AL0809X) that appears to fit this application, which has sealed (or, partly sealed) VR brushes. I wonder if that would be better for off-roading.

That's exactly what I need. How did you figure that one out?

I'm definitely going to have to find one of those.

 

[gsxr]

That's exactly what I need. How did you figure that one out?

I'm definitely going to have to find one of those.

IIRC, it was @speedy300dturbo that discovered the Range Rover interchange a few years back. The alternators look the same from the outside (other than possibly needing a re-clock, depending on the engine) but their is a weatherproof shroud around the brushes AND slip rings.

Hey Bim, guess what! I found photos on my website! Totally forgot about them...

 

[Beater400E]

IIRC, it was @speedy300dturbo that discovered the Range Rover interchange a few years back. The alternators look the same from the outside (other than possibly needing a re-clock, depending on the engine) but their is a weatherproof shroud around the brushes AND slip rings.

Hey Bim, guess what! I found photos on my website! Totally forgot about them...

View attachment 223068 View attachment 223069 View attachment 223070

That's cool. The brushes look to be basically the same as the brushes on my voltage regulator. They appear to be enclosed in the same way. Different part number, but I don't see any extra seal to limit dirt ingress. I do see one around the slip ring though. My junk yard only charges $30 for an alternator, so I'll definitely snag one when I can.

 

[gsxr]

The Mercedes alternators have fully exposed slip rings and brushes, no seals at all:



The Rover version seals the contact points:

 

[Beater400E]

I didn't see the brush holder seal at first, but I think I see what you're talking about. My junk yard had a 2001 Range Rover with a fresh looking alternator, so I snagged it. I think I'll pop it open and have a look before I installed it.

I did reinstall my alternator and test after cleaning the brushes, and it does now work, so that was the issue for sure.

 

[Beater400E]

Or not.

Whoever built this one didn't feel like using the sealed parts I guess.



So I'll just leave my standard 150 amp alternator in there.

 

[Beater400E]

Windows that keep the outside out! Best $85 I ever spent.

 

[Beater400E]

Totally unrelated to today's work... I ordered a PWM fan controller from Dave Brown (Microautonomation) in early August. It's been over a month and I haven't heard anything. I emailed a few days ago for an update, but haven't received a response. I wonder if Dave is still around.

I'll probably request a PayPal refund and see what happens. I assume if I get the refund that's the end of it.

Edit: I should have checked my email before I posted this. Dave replied and said he'd had trouble getting enclosures but that he finally had them and would be sending my order right away.

 

[gsxr]

Edit: I should have checked my email before I posted this. Dave replied and said he'd had trouble getting enclosures but that he finally had them and would be sending my order right away.

Thanks for the update! I need to order one of these to experiment with.

And, I need to figure out which OE fan requires the least modification to install on the 034/036 chassis...

 

[Beater400E]

Thanks for the update! I need to order one of these to experiment with.

And, I need to figure out which OE fan requires the least modification to install on the 034/036 chassis...

I have basically every OE fan on hand. My plan is to do a technical deep dive and write-up on installing a fan in these cars. I plan to install one in the 500SL. I already have one in my 400E, and I plan to show some more detail on that setup, but I'll also share measurements on all the different OE fans, options for mounting and ways of dealing with tight clearances, and then of course controlling and wiring everything.

Some day.

 

[gsxr]

I have basically every OE fan on hand. My plan is to do a technical deep dive and write-up on installing a fan in these cars. I plan to install one in the 500SL. I already have one in my 400E, and I plan to show some more detail on that setup, but I'll also share measurements on all the different OE fans, options for mounting and ways of dealing with tight clearances, and then of course controlling and wiring everything.

Some day.

This would be awesome. In particular, figuring out the dimensions of the various OE fans to see which need the least modification to fit. The 204- fan even has lower tabs that slide into the stock 034 radiator brackets, but I think other stuff doesn't quite align if you do that.

The stock fan clutch bracket is also a nuisance as it pokes forward substantially. I know you replaced the stock bolts with flats to add a few mm clearance, it would be nice if one of those wall art items might fit with stock bolts... probably a moonshot though.

 

[Beater400E]

The stock fan clutch bracket is also a nuisance as it pokes forward substantially. I know you replaced the stock bolts with flats to add a few mm clearance, it would be nice if one of those wall art items might fit with stock bolts... probably a moonshot though.

I can mock it up and find out.

 

[Beater400E]

I got everything on my list done and I hit the road this morning. Along the way the car has started doing its annoying surging thing again. Wide open throttle, above maybe 70 mph, it bucks hard whenever I try to pass someone on the highway.

Last time it did this I reset LH adaptation and that resolved it. I'm stopped in Winnemucca Nevada for fuel right now and I'm going to reset adaptation before I get back on the highway. Hopefully that will take care of it. Wish I knew why it was doing this. I'd love to prevent it.

 

[Beater400E]

Oh yeah, and I barely made it out of town when a car kicked up a piece of lumber on the freeway and did this.

 

[Beater400E]

No change. Still does not want to go fast.

 

[gsxr]

No change. Still does not want to go fast.

Well shoot. That's not good. Remind me - do you have SDS / HHT-Win available (at home)? Not that it would help you on the road.

I am suspicious you might be experiencing fuel starvation under load. This can result in severe bucking under heavy throttle. Difficult to pinpoint without a remote fuel pressure gauge you can watch while driving.

 

[Beater400E]

Well shoot. That's not good. Remind me - do you have SDS / HHT-Win available (at home)? Not that it would help you on the road.

I am suspicious you might be experiencing fuel starvation under load. This can result in severe bucking under heavy throttle. Difficult to pinpoint without a remote fuel pressure gauge you can watch while driving.

I don't have SDS. The fuel pumps and filter are brand new.

 

[Beater400E]

Stopped in Lovelock. I figure I'll give everything a once over and scan codes. Next stop will be Reno, which is probably my last chance for parts if needed. I'll be rallying just north of Yosemite all weekend, so not great access to parts.

 

[Beater400E]

17-5 knock sensors faulty.
17-8 overload switch does not close.
19-5 EGR faulty.

That 17-5 knock sensor fault is not great.

I cleared all the codes. Back on the highway.

 

[gsxr]

Oh yeah, and I barely made it out of town when a car kicked up a piece of lumber on the freeway and did this.

View attachment 223105

Any chance the '94 at the Jungle has good headlights?

 

[gsxr]

17-5 knock sensors faulty.
17-8 overload switch does not close.
19-5 EGR faulty.

That 17-5 knock sensor fault is not great.

I cleared all the codes. Back on the highway.

Knock sensor fault shouldn't cause bucking... maybe a slight power loss, but that's about all I'd expect.

OL switch can cause a funky WOT shift. Checking the wiring, but the switch might be defective. Swap in a spare if you have one.

EGR faulty. Oh darn.