RPB

Hey Guys,

The summer has been hitting hard here in VA lately, the car is sitting around 101-102 in traffic and then cools when the aux fans kick on. I sold my 500e yesterday, and have some extra change to throw at this car. I had the water pump changed 12-15k miles ago, it just dawned on me recently that the viscous clutch is most likely the culprit and I never hear it running. I'm not a believer in the whole theory that these cars should be hitting 100+ like this, i get it that MBs of this era run hot, but this to me is a little too hot. The car seems quite a bit bogged down when it hits these temps, if anything I want to replace it as preventive maintenance. I witnessed my 500 hit a 100c once, that was after sitting in traffic for one hour when the temps were 90+ and it cooled much quicker when I started driving!

This brings me to my question which is whether or not this is a pretty easy job to tackle? I viewed a few clips on YouTube that make it seem somewhat easy, I am a little scared by two things and that is one or two of the tools required and the fact that the bolt just spins with the engine when trying to remove it. I was quoted 1-1.5 hr labor at a local shop which does not seem to be bad, I just like the self satisfaction I get from replacing stuff on my own and of course the money I save. Can someone give me some tips on their experience replacing and a good diy for it please? I also stumbled across an updated fan with more blades (part# 1032000423) and was curious if this helps, I would assume so having more blades. Any help w/ this would be very much appreciated as always!!

1995 C36- 139k

Cheers,

-Rob

Tony_AMG

have to remove radiator for full access. should not be that difficult and basically drain radiator, remove radiator, remove engine shield, r&i upper tie bar. have fan clutch tool, and counter clutch tool as well. maybe like a 3-4 hours job taking your time. but worth it as you can replaced pulleys or other things you can look at.

RPB

You do not have to remove the radiator:



I do appreciate your response!

Sulaco

Is that a c43 in the video? Different situation, being a v8. I had to remove it just to do lower heater hose.

vinceC

I have done it several times on my son's C43. I did not pull the radiator. Just use both tools, and when the fan is loose remove it along with the shroud (as a pair).

That said, I don't think 100 is too high at low speeds. The engine driven fan can only pull so much air at low engine RPM, hence the auxiliary fans. As a test, open the hood, manually raise the engine RPM to 3,000 or so and listen to the fan. It should be pulling pretty hard in the temps were are seeing the last few days.

Super B

Done it many times with out the special tool and just a strap wrench. It's not too hard but can get ugly/miserable if the clutch has been previously over tightened.

Just a suggestion, but have you verified the thermostat is working properly? Might want to check that before diving into the clutch fan. It's super easy and quick.

RPB

I appreciate all the help guys! Very helpful and responsive section of the site here!! I hear you Vince, what you're saying does make sense to me. It was quite humid here today, I took these pic's and I was barely sitting in any traffic when it was registering these temps. Do you think this is normal? I will try the test you recommended, it was raining all day and did not have the chance to rev it up like you told me to. Please let me know your thoughts:

cm60k

I think it should not reach that much..!,,

do you know if your aux. fans works when it reaches 95..?, or are they works when switch-on A/C..??

ZAYED,,

RPB

I agree Zayed, this is not right and I am about to order a Behr fan clutch and the updated fan w/ 9 blades. The car runs very bogged down when it hits these temps too, I know something is out of order. My A/C has a leak that I want to get fixed, but I would dare to it with the current temps it's operating at without it on. This is the main reason I need to get this sorted, the temps in VA are rising quickly and I need my A/C back. Got to figure this out first though. The parts will cost me $125-30, so i will not be kicking myself if there are no results.

I will post back after I get everything installed next week.

Thanks!

cm60k

Not bad to replacing fan clutch & A/C leak, but maybe your fan clutch is good, need to see about aux. fans operating,

cause they controlled by small module, at the driver side wheel arch,

if their are not enough gas in A/C compressor aux. fans will not operating,,

also if module fail, aux. fans will not work, that will cause overheating issue..!

did you try to diagnose the car..?

ZAYED,,

RPB

Yes they seem to operate fine, it comes on around 95 and run at a higher speed when it gets 100+ then the temp goes down to about 90-93, if I am sitting in traffic though it gets right back up to 100 within minutes.

What would you recommend I do? Shops in my area are clueless about these cars, I have no problem taking it to the dealership and paying ridiculous prices if it gets fixed right. The car has treated me so well in my 7yrs of ownership, this will now be my primary as I just sold my other MB and need it running well ASAP.

Thanks!!

cm60k

While they operating, means module works fine,

as you said, seems like clutch not pulls are strongly,,

when the car off, try to rotate the fan by your hand, see if it rotate freely, or not..?

ZAYED,,

RPB

I feel like they're running ok. I rotated the fan when the car was off, it did about three to four revolutions before it stopped. There seems to be some resistance which is what made me think it might not be the fan clutch. Would you start by trying out a new fan clutch? A little baffled at this point! I appreciate your quick responses!!!

cm60k

Yeah, if it rotate as four times, seems it's starting to fail-out, try to replace it,

and in the same time; diagnose the car to see if ECU saved anything related to the temp. system..!

ZAYED,,

RPB

Okay Zayed, I am ordering the parts this evening and installing when I get back from a trip early next week.

How would I check out the ECU data? Does this require the MB star diagnostic?

Thanks!

cm60k

Sure, MB STAR/SDS is the best for diagnosing..

ZAYED,,

RPB

That was more of a rhetorical ?. The fan clutch/blade will be swapped out next Wed, I think this part is the culprit but it's time to verify.

Thank you!

cm60k

....

vinceC

All our cars run in that range sometimes (C280 with M112, E430 and C43) so I am not alarmed. You say you were "barely sitting in traffic", however your speedo shows you are stopped with the engine idling. Also, was the ambient temp really 71 degrees Fahrenheit? That isn't what I would consider warm. Does the temp drop significantly when you have been moving for a few minutes? When idling does the temp hold at that temp or rise further? Is the A/C on (compressor engaged) or have you disabled it?

The fan clutch never "locks up". It is similar to a torque converter. The amount of engagement is controlled by a bi-metal spring that controls the stroke of an internal valve. The valve controls the movement of internal "clutch" fluid. As the temp coming off the radiator rises the bi-metal spring senses it, fluid flows to increase drag inside the unit and the fan speeds up. Usually the fan speed tops out about 4,000 RPM. Keep in mind that the engine driven fan draws significant HP when "engaged" and that is why it is there, i.e. to reduce unnecessary power draw. Adding a nine blade fan will also increase power draw. Once rolling and airflow from vehicle speed increases the fan should freewheel since it is no longer necessary. The point is that if indeed the fan is not pulling correctly, replacing it with a correctly functioning unit may make the power drop seem worse.

Do the test I recommended. It takes 30 seconds. Other causes of warm temps can be the thermostat (as mentioned above), the radiator, debris blocking airflow or a faulty temp sensor.

Sulaco

I agree that temp is slightly high for sitting in traffic in 71 degree weather with the AC on.

My 98 has no fan clutch or fan on it right now, as well as no freon in the AC system so the aux fans don't come on either. It never gets that hot.

Your fan shouldn't give you 4 rotations if you spin it with the engine off. I agree it needs replacing, but I doubt that will fix your problems. A functioning fan clutch will bog your engine down at high temps really badly, too, so there's that. Have you tried spinning the fan after the engine his hot like that?

And take vinceC's advice and consider your thermostat. My car with working AC doesn't get this hot and I know I need a new fanclutch too, and it's up past 90 F here now.

Also, I'm pretty sure aux fans should come on in stages, and the first stage occurs well before 95C. Mine come on at around 85 on the first stage, if I recall correctly.

vinceC

Boy do I feel dumb. I completely overlooked that the OP has a C36! I had a C280 with the M104. Temps that high at a stop were the norm for that car, in warm weather, even with new radiator, thermostat, fan clutch, etc., etc. The aux fans would be on, the fan clutch engaged, the works and it still crawled up to 95 or so. 71 degree ambient isn't particularly warm though. I haven't seem 71 here for a couple weeks, even at 0530.

And fan removal instructions are different. IIRC, you just lock the pulley with a 1/4" rod bent about 15 degrees at the end, then use a special shorty socket on the clutch. Sawed off Allen key and short piece of pipe will work too.

Sulaco

oh hell, that is a C36! you're right.

hahaha those temps are actually pretty good for a C36 sitting in traffic

cm60k

Agree with vinceC,

Here, temp reaches around (118F), with A/C on, in traffic, it not reach 100..!,,

unless if something wrong with "T.stat>fan clutch>>aux. fans>>>aux. fans module", those should to be checked before touching Radiator..

ZAYED,,

mkoons

RPB
Your car indicates outside temp of 71F, I live in So CA desert and we're having a hot week, temp running 112-116 and my car would not exceed 88 degrees.

vinceC

Everyone needs to keep in mind that this is an M104, not an M112/113. There is a big difference; I've owned both. Furthermore, the 71 degree reading doesn't make sense. We've been in a major heat wave here in Virginia, with temps in the high 90's to over 100 degrees. Only the OP can explain.