Overheating - Page 3 - PeachParts Mercedes-Benz Forum

Father Of Giants · #31 01-27-2018, 07:03 PM

Quote:

Originally Posted by sokoloff

Took the car out tonight. Temp was a solid stable temp just below 80 like always. Shutting the car off, the fan freewheeled for a bit, way more than the normal two or less rotations. Did the newspaper check too and it stopped the fan. So I guess the diagnosis is a bad fan clutch correct? Never got it hot enough to kick on the aux fans, but that doesn't seem like it's needed now.

So my next question is what's the hurry to replace the clutch if the normal driving temp is where it should be? Guess the issue would be if I ever get stuck in traffic again.

Thanks again for all the help. Not sure whether I want to attack this myself or not. Might be a lot easier to just write a check.

https://www.youtube.com/watch?v=r0EBTkbTzPY

sokoloff · #32 01-27-2018, 07:40 PM

Thanks for the You Tube link, but that is for an AMG, i.e. different from my diesel. However, the second video there is for the diesel. Looks like a DIY job if I can get the right tool.

vstech · #33 01-27-2018, 07:54 PM

if your cooling system is clean, and fresh coolant is present, at idle, under 120 shouldn't cause any ill effects. it's a condition you now are aware of, so in long non moving drives, be sure to raise your ac temp...

yes, replacing the clutch will help, as will verifying your electric fan setup is fully functional.

it wouldn't hurt to verify your serpentine belt is in good condition, with a good condition tensioner as well.

sixto · #34 01-27-2018, 08:01 PM

A stubby 8mm or is it 10mm hex bit loosens the bolt. It has to be stubby so you can remove it before it gets too close to the radiator and whatever you slip in place to protect the radiator fins. After breaking the torque, I used a hex key with a box wrench slipped between the short end and the bolt to make it easier to spin continuously.

A pulley holder helps tremendously. Harbor Freight stopped selling this but you can make or buy something similar. It doesn’t need to be adjustable.

I believe the 606 like the 693.97 water pumps have a ridge to hold a ~3mm rod from behind ala M103 but I have great difficulty lining up the keyway on the backside of the pulley. The pulley holder requires only as many elbow joins as I have.

Sixto
98 E320s sedan and wagon

Mxfrank · #35 01-27-2018, 09:07 PM

Quote:

Originally Posted by Diseasel300

The bimetal strip is significantly lower for the turbo 606, in the 72Cish range, one of the big reasons the turbo 606 fan clutch is considered an upgrade from the turbo 603 clutch with a higher operating temperature.

I think you're confusing air and water temperature. The 602/603 fan clutch engages at 71C AIR temperature. Because temperature is inefficiently transmitted by airflow, this equates to water temperature of around 95C. I think the 606 clutch works exactly the same. Switching on at 72C WATER temp would be a waste of fuel. You can't check fan engagement at normal operating temps, the engine has to be hotter.

Diseasel300 · #36 01-27-2018, 09:44 PM

Quote:

Originally Posted by Mxfrank

It's a thermostatic clutch, so it will only engage at relatively high air temperature. I think the thermo strip is set for 95C.

I'm aware the bimetal strip is measuring air temperature. The 95˚ is the coolant temp at which the bimetal should fully engage, translating to ~72˚ at the bimetal strip.

If the engine is up to operating temperature and the radiator is throwing heat, the fan clutch should be partially engaged, so basic operation can still be checked. Even when disengaged, there's the drag of the silicone fluid in the clutch mechanism. Spinning it by hand should give a revolution or two, but it shouldn't freewheel like it was running on bearings.

Mxfrank · #37 01-27-2018, 10:04 PM

Quote:

Originally Posted by Diseasel300

I'm aware the bimetal strip is measuring air temperature. The 95˚ is the coolant temp at which the bimetal should fully engage, translating to ~72˚ at the bimetal strip.

If the engine is up to operating temperature and the radiator is throwing heat, the fan clutch should be partially engaged, so basic operation can still be checked. Even when disengaged, there's the drag of the silicone fluid in the clutch mechanism. Spinning it by hand should give a revolution or two, but it shouldn't freewheel like it was running on bearings.

At lower temps, there will be about 20% engagement due to fluid viscosity. It isn't completely free on it's bearings. But it engages all at once, so you really can't say whether it's working correctly until the engine reaches 95. When fully engaged, it still slips, and will only turn at about 80% of pulley RPM.

tjts1 · #38 01-27-2018, 10:14 PM

Quote:

Originally Posted by sokoloff

So my next question is what's the hurry to replace the clutch if the normal driving temp is where it should be? Guess the issue would be if I ever get stuck in traffic again.

On the W210 if you press and hold the 2 AUTO buttons on the climate control for 10 seconds, you can turn on the AUX fans at max speed at any temperature. Check that both fans are spinning. Only the driver's side fan has a motor, the passenger side is belt driven.

sokoloff · #39 05-31-2018, 06:41 PM

Thought I'd update this thread I started. I hate it when people don't tell us about the final outcome.

Well in my case it may not be a final outcome, but here is an update four months after the fact. Took the car on a 400 mile repeat trip of the one that started this. Everything the same except that I was never stuck in traffic idling for 45 minutes. The car's temp never went more than a needle width above 80 and for the most part was a needle width below 80. Never had any issues. Most of the driving was at 75 mph with a little city stop and go traffic.

After all the suggestions above, I think I determined that my issue was likely the fan clutch. However, I rarely drive the car and when I do, it is typically a highway run that is too far for my Smart electrics. Over the past four months I've put about 1000 miles on the car, so for the time being I'm just going to leave well enough alone.

sokoloff · #40 08-10-2018, 01:53 PM

Another update - my son was visiting and he kind of twisted my arm to deal with my potential for overheating and doing serious damage to a pretty nice car. Because he twisted my arm, I really could only hold the shop light while he did the work.

So we/he removed the auxiliary fan unit after determining that it wasn't working. We also overnighted a fan clutch from RM European and replaced the fan clutch. I was pretty sure all along that the fan clutch was bad. I did the newspaper test and the free wheel spinning test mentioned above. They seemed to indicate to me that the clutch was bad, but since I rarely used the car and when I did, it held the temperature okay, I put off doing anything. The video(s) mentioned above were helpful.

So I do feel better now that the fan clutch is repaired. The auxiliary fan unit is sitting in my garage. I'll be getting a new/used fan motor and replacing that one of these days.

sokoloff · #41 11-24-2018, 04:57 PM

Well it only took me 10 months to get this thing fixed. My son visiting over Thanksgiving installed the new auxiliary fan unit and I now have those working. That was a pretty easy job. While we were at it, I/he also replaced the air dam unit surrounding the radiator. That was the hard part, i.e. trying to force that thing around the radiator without disconnecting any AC lines or coolant hoses. We eventually got it in and it looks better, even though that wasn't a critical part of this operation.