Help - Got to HOT

[KarlC]

As some of you know I just picked up a 94 E500 with 160K miles, I got it in San Francisco and drove it home that night 500 miles to Del Mar. I was keeping a close eye and ear on it all the way home to make sure all was ok and it was, all went great.

Today I soaked the motor and under carriage with degreaser and and carefully pressure washed it all, I did this a few times.

She started right up and ran great again with no issues, but about in 10 minuets I look see the temp gauge at maybe 110, so I turned off the AC and cranked up the heater as I have always been told this helps cool the motor down. I kept the car moving at a good speed to keep cool air moving across the motor, but the temp slowly moving up until it hit 120. At this point I'm worried it's losing water or some other big issue, so I pull over turn it off and pop the hood but all looks ok. The over flow tank is 1/2 full, its hot but not boiling, so I let it cool down for about 30 mins until its reads 80. I then drive it home for another 10 mins and the temp reaches just over 90, at home I pop the hood and again all looks normal. The only odd thing I can find is that the washer tank and fender next to the over flow tank are both HOT I can't keep my hand on them, they feel much hotter than the over flow tank.

Any clues ? What do you think a bad thermostat ?

Thanks guys
.

 

[Ron500E]

Hello:

I will let others chime in about the problem but I will say NEVER pressure wash the engine, no matter how careful you may be. Too many electronic things that are allergic to water.
I know it is a REAL PITA to clean an unclean engine but it is worth the effort.

Kind Regards,

Ron

 

[edcarls]

... I was keeping a close eye and ear on it all the way home to make sure all was ok and it was, all went great.

Today I soaked the motor and under carriage with degreaser and and carefully pressure washed it all, I did this a few times.

She started right up and ran great again with no issues, but about in 10 minuets I look see the temp gauge at maybe 110...

Any clues ?

You drove 500 miles and everything was ok. But, after engine wash it got hot. My guess is some wire got wet (shorted/grounded) which caused the sender to send wrong signal to the gauge.

I hope it's that simple. Anyway congrats on your find.

 

[edcarls]

Ron,
I was typing while you are posting. And I'm not surprise to see we are on the same page. I too had a lot of bad experiences with engine pressure washing. Now I just use brake cleaner.

 

[redred]

Brake cleaner? That's an interesting one. Care to elaborate?

Sorry for your troubles Karl. I hope it's something simple

 

[Jelmer]

We used brake cleaner to wash that plastic underside protection thingie on my car. Works wonders. Spray it on, wait a bit, wash all dirt and goo off. According to Christian, it's expensive though. And it seems to be quite an aggressive cleaning agent, so I wouldn't want to use it near connectors, sealing rings, hoses, etc.

Now back to the topic: if you search on the forum for related topics, you'll find some of mine. I had issues as well, but even at 30C, with AC on, and full thottle for longer times, I hadn't seen >110C. Imho, it shouldn't ever reach that mark, because that would mean the viscous fan AND the aux fans are at full speed, which would move insane amounts of air.

Some things to check:
- Does the viscous fan work? It should kick in around 90-95C on the dash, and give a nice roar when you rev the engine
- Did the aux fans switch on at that temperature?
- Does the radiator get hot evenly? With my car, the lower 4-5 paths were full of junk, meaning I'd lost about 10% cooling capacity.
- Does the thermostat open at ~80C, and open fully? The upper hose should start getting warm when the dash gauge reads 80, and slowly get hot.
- If it's not doing its overheating games, is the dash gauge at around 80-85C? That's the operating temperature, and would tell you at least the dash gauge is OK.

And of course the whole upper wiring harness dance...

 

[gerryvz]

Simple Green or any sort of engine degreaser or citrus cleaner works well to clean an engine. I wouldn't hesitate to use brake cleaner on the UNDERSIDE and metal areas, and certainly use it to clean off the surface of my protection shield under the engine. For folks in the US, Griot's Garage makes an engine cleaner/degreaser that is pretty good stuff and that won't harm your engine....

Spraying water (particularly under high pressure) is a recipe for disaster.

Citrus cleaner, Simple Green (perhaps diluted 50-50 with water) or a special engine cleaner, a little bit of water poured judiciously, and a LOT of elbow grease is really the best way to do things....

http://www.griotsgarage.com/product/engine+cleaner,+35+ounces.do?sortby=ourPicks



Cheers,
Gerry


P.S. When I cleaned my engine block when I did my M117 rebuild, with the heads & top-end off the motor, I used brake cleaner. Here are some before and after photos....

 

[gsxr]

Assuming you have no service records, I would flush the cooling system and replace the thermostat (with OE/OEM only!) along with fresh G-05 coolant. If you do that, I'd also change the plastic reservoir if it's original, along with the radiator cap. All are cheap insurance.

Water on the wiring would not cause a high temp reading on the gauge, btw. The electric fans should have been on high speed by 110C. If not, you have another item to check out. The viscous clutch is also suspect. Finally, the fluid level in the plastic radiator tank should be at the seam when cold, and above the seam when hot. If it's "half full", the level is low (but that should not cause the high temps you describe).

 

[KarlC]

First all thanks for all of the input guys !

I'm sorry if I sounded like a bit of a newb, there surly is a wrong way to pressure wash a motor (I did that mannnny years ago) but there is a right way (masking off) to do it also. This car's under hood / body was a mess it has not been cared for since 1994 so it needed it badly. I've never tried break cleaner as I did not want to damage any paint, plastic, stickers, ect.

On to the problem.....

I'll have to check the times you all listed, I have a show and tell planed for latter today with Glen and I'm sure he will be a big help !!

By the way the plastic radiator water line is this AM is right above the seam, I think that is where it was at when it got so HOT. I thought that it was odd that it was NOT boiling over, so after a min of cooling off with a rag I slowing removed the cap and it still did not boil over at all.

I have a ton of service records from day one that I still have to go thru. some are hard to understand due to just numbers being listed, part numbers I assume.

 

[redred]

Good luck. Looking forward to an update.

 

[KarlC]

I got the pleasure of meeting up with Glen yesterday, he is such a great guy and has so many cool ride !

We took my car out for a spin with Glen at the wheel, with the car under load (like going up a small hill on the gas) you could see the temp slowing rising, then when it was not under load it would cool right down. Back at his house we found that the Auxiliary Fan Relay fuse was blown, so once we changed that out then the fans kicked on as they should.

Latter going thru all of the PO records on the car I found that this fuse has been replaced before, it's a 15 amp fuse, Glen is wondering if that was a past TSB on using a bigger fuse ?

I will keep using the car and keep you all updated.

Thanks

 

[bing]

Aside from the fans, did Glen think it drove as it should ?

 

[gerryvz]

I got the pleasure of meeting up with Glen yesterday, he is such a great guy and has so many cool ride !

GLEN​

​

 

[TerryA]

Karl,

You and Glen got the Aux fans fixed before I could suggest checking the fuses. I just had that same problem recently.

My fans were not working for a long time but I have a new radiator, thermostat, expansion tank and cap so it was only

getting warm in freeway traffic jams on hot days and would always cool down if I moved at all.

Anyway I am a terrible auto electrician so I finally paid a Tech to find the problem.

It turned out the fuses were just corroded. All he did was clean them up. A second contributing factor to the fans not

coming on is low refrigerant in the A/C system. In my case the Tech added 1 pound of R34.

My main reason for posting here is I also use brake cleaner once in a while for cleaning parts.

"BE CAREFUL WITH BRAKE CLEANER IT REMOVES PAINT AND MELTS PLASTIC"

I find that MINERAL SPIRITS is a great cleaner on motor parts an it leaves no after affects.

>>>>>NEVER USE WATER

Just Saying

 

[Glen]

Yes, it drove quite nicely, the trans shifted well, and the SLS rode smoothly. I think mechanically, the car was taken care of pretty well. And other than the obvious cosmetic issues, it's a great car...I believe Karl got a great deal.

 

[gsxr]

I am not aware of any TSB to increase the size of the fuse. I would check the connections at the ceramic resistor and make sure they are not corroded. Increasing fuse rating is generally a Very Bad Idea.

For the rest of the folks reading this thread... the 1994-up models do not have a 30A strip fuse for the auxiliary fans: they have two fused cube relays, one for low speed with a 15A fuse, and another for high speed with a 30A fuse. Totally different setup than 1993 and older.

 

[Glen]

Several years ago when I had cooling issues with my wagon, I received help from Arthur Dalton on Peach Parts. He was the one that mentioned to me that MB changed the spec on the aux fan relay fuse. Here's a post that mentions it: http://www.peachparts.com/shopforum/2514217-post8.html

I never did confirm that MB actually changed the specification but I do trust Arthur and my wagon has been fine with a 20A fuse.

 

[KarlC]

GLEN​

​

King Glen !!! My thoughts exactly !


Thanks for all of the input guys, I will keep a close eye on it.
.

 

[gerryvz]

the 1994-up models do not have a 30A strip fuse, they have two fused cube relays, one for low speed with a 15A fuse, and another for high speed with a 30A fuse. Totally different setup than 1993 and older.

FYI: For those with the 1994s, these cube relays are located in the relay corral immediately to the rear of the fuse panel.

 

[Glen]

For the rest of the folks reading this thread... the 1994-up models do not have a 30A strip fuse, they have two fused cube relays, one for low speed with a 15A fuse, and another for high speed with a 30A fuse. Totally different setup than 1993 and older.

I haven't look specifically on my E500 but on my '95 wagon, there is a fuse strip and it powers the cabin fan. I learned this the hard way on a trip to Las Vegas in the middle of summer! The a/c compressor would engage but I wasn't getting any air flow inside. Don't laugh and don't try this at home, but I was able to band-aid the problem and get home in comfort by using two small paper clips to replace the fuse. Why two? Because I tried one first and it burned up almost immediately...two did the trick and got us home with nice cool air.

 

[gsxr]

Yes - all 124's from mid-1987 production through end of production in 1995 use the 30A strip fuse for the HVAC cabin blower motor. I'll clarify my previous post.

It was the auxiliary engine cooling fan fuse which changed from 30A strip to ATC-style fused cube relays as of 1994 model year. 1993 and older 500E's will have two 30A strip fuses.

 

[gerryvz]

On my E500 as well as my wife's E320 wagon (a 1995 model) there IS a 30 Amp strip fuse, but this controls the blower motor (forces cool or hot air into the cabin through the side, foot and center dash vents). Three years ago or so, this strip fuse failed (probably from age, etc.) on the wagon, so I replaced it.

Last weekend, I took my family down to the beach on Galveston Island in the 1990 560SEL. We stopped at an open house at a brand-new beach house that was for sale (don't get jealous ... $360K for a brand new beach-front house), and I was sitting in the car, idling with the A/C on while my wife was checking out the house. The fan suddenly kicked off and I checked out the strip fuse and yup ... it was blown. Heat, use and age finally took its toll on the ol' 22-year-old original strip fuse....needless to say, it was a HOT, 70-mile ride back to The Woodlands on I-45 with the windows partially down at ever-increasing temps as we drove inland.

When my fuse failed on the wagon a few years back, I bought a couple of extra strip fuses, so of course had one right at hand when I got home to replace the zapped one on the 560SEL.

The externally fused, green "ice cube" relays that Dave was talking about are for the two-stage auxiliary fans, not the blower motor. Different systems...

Cheers,
Gerry

 

[mb280sel1985]

It turned out the fuses were just corroded. All he did was clean them up. A second contributing factor to the fans not

coming on is low refrigerant in the A/C system. In my case the Tech added 1 pound of R34.

Seriosly, how does low refrigerant in the A/C system affect wheather aux fans come on or not?

I've never had the A/C working the time I've had my 500E. Haven't bothered to fix it, since we barely see ambient temps above 75-80F here.

I had it filled with refrigerant though, since my mechanic got a brand new Waeco automatic refill station, and offered me a try. The machine did a 30 minute leak test. Found no leaks. Continued with the refill program, and completed the whole process successfully in 1 hour.

It blew cold air for 2 days, and then nothing. Back to not working again. I haven't pursued the problem after that.

So, why am I writing all this? Well, my engine always goes up in temps when in stop and go traffic. It will go to appx 110C. So I'm really interested in how the A/C system would affect engine temps, working or not working.

 

[gsxr]

Seriosly, how does low refrigerant in the A/C system affect wheather aux fans come on or not?

The electric fans turn on low speed based on refrigerant pressure. The fans turn on high speed based on coolant temp (on at approx 107C, off at approx 100C).

So, why am I writing all this? Well, my engine always goes up in temps when in stop and go traffic. It will go to appx 110C. So I'm really interested in how the A/C system would affect engine temps, working or not working.

When the AC is working, it pulls heat out of the passenger compartment and dissipates that heat via the condenser in front of the radiator. This increases the heat present at the radiator and can make the engine temps increase compared to when the AC is not turned on.

If your engine temp is up near 110C with the AC not functioning (which adds extra heat load, which you don't have)... that ain't right. Your electric fans should turn on high by 110C. To test fans, turn the key on (or let engine idle) and remove the 2-prong connector from the sensor at the front of the intake manifold. The fans should turn on high speed within a few seconds. IF they don't, find out why (blown fuse, etc). I'd also check the fan clutch... on a warm day with the temps at >100C you should be able to hear the fan roar past 3000rpm. If not, your clutch may be toast. You could also have some other issues... radiator? system not holding pressure? bad cap? etc, etc...

 

[2phast]

I use Griot's engine cleaner as well. Most of the time, I just rinse my engine bay with water to clean out the dirt. I would not recommend anytype of high pressure water. A low stream of water from your hose is suitable to rinse your engine bay. You can control the water stream so as to keep water away from delicate areas. When finished, I always start up the motor and let it run for 10-15 minutes to dry out. Never, ever had a problem with this tactic.

 

[KarlC]

I got the pleasure of meeting up with Glen yesterday, he is such a great guy and has so many cool ride !

We took my car out for a spin with Glen at the wheel, with the car under load (like going up a small hill on the gas) you could see the temp slowing rising, then when it was not under load it would cool right down. Back at his house we found that the Auxiliary Fan Relay fuse was blown, so once we changed that out then the fans kicked on as they should.

Latter going thru all of the PO records on the car I found that this fuse has been replaced before, it's a 15 amp fuse, Glen is wondering if that was a past TSB on using a bigger fuse ?

I will keep using the car and keep you all updated.

Thanks

Just wanted to loop back to all of you on this.

After we changed out the fuse there have been no other issues with it getting hot or even to warm for that matter, all is good.

I'm still not sure why the gauge read 120, as I said the water was not that hot, it did not boil over, put out any steam or even feel overly hot. What even it was its gone now.
.

 

[vatc5637]

That's great news. Hope that does it. But, if the fuse blows again, check the aux. fan low speed resistor (or the connecting wire). I blew three 15A fuses before I took GSXR's (and others) advice and permanently fixed the underlying issue by replacing both the wire connector and resistor.