1987 300E coolant temperature / fan clutch
 

Hello

I have a 1987 300E since 2001.

I have noticed when the vehicle sits in stop and go traffic or if I leave the car running when I get home for 10 minutes or so the temperature slowly creeps up and eventually the electric fan comes on at 105C, and it seems to stay on, or go off briefly and come back on.

The radiator and thermostat are in good shape.

I am thinking the fan clutch might be a bit worn.

The fan clutch does engage and spin however I was told that it didn't seem to spin that fast. I was told they tend to roar a bit. My fan clutch plastic fan version has 11? blades. I see that the replacement is 9 blades.

Its behavior has been the same since I have owned it (18 years).

I recall reading threads over the years that other owners mentioned that the temp creeps up in stop and go traffic.

There is a youtube video that shows the safe way to test it.

When the car is cold by had the fan will spin for 1 to 1-1/2 revolutions. When hot and the engine turned off the fan continues to spin for a while. The video mentions it should come to a stop much sooner.

Any ideas how to be certain my fan clutch isn't working at its peak.

I'd rather not have it changed out unless I am certain it is bad.

???

Thanks

You've already diagnosed the clutch as bad. Freewheeling on shutdown is a classic symptom of a bad clutch, even when ice cold it shouldn't freewheel. A bad clutch won't transmit power to the fan to actively draw air through the radiator. If the coolant temp were getting that high, you should definitely hear it roaring a bit when the engine is revved. While you're doing maintenance, wash out the A/C condenser, and wash between the condenser and the radiator. You'd be surprised the crap that builds up in there.

The car sat overnight, this morning the temperature was 59F or 15C.

When I started the car the fan clutch fan was spinning.

Wanted to confirm that it should NOT spin at this temperature?

Thanks?

The fan always spins, but when it's not engaged it's slipping and not a full speed.

The fan should always be spinning, even if the clutch is not engaged. The fluid in it creates some drag so that it spins, but slips. When working properly, the fluid increases the drag in the clutch, reducing slippage, so that the fan runs faster and draws more air. Freewheeling at shutdown is a sure sign the clutch is garage and has been junk for a long time. A good clutch will stop just about immediately or maybe coast a fraction of a rotation. Replace it. A fan clutch is cheaper and easier than a head gasket.

Just add some silicone oil to it. If you want, I have a heavy duty clutch that I used to run in the summer before upgrading to the electric fan. I think I put in 2500 cst silicone. When it engages you definitely hear it. Think of being next to an 18 wheeler when it takes off from a stop. The good thing is that once it engages, you're engine is cooled to temp within a minute or 2.

Our forum host offers URO Fan Clutch 103 200 0422 for the 1986-1993 300E, which has nothing but 5-star reviews on one of the big retail sites. https://www.pelicanparts.com/More_Info/UR1032000422.htm?pn=UR-103-200-0422&bt=Y&fs=0&SVSVSI=3303

Bought this exact fan clutch and it failed after a little over a year and 15k miles.

Hi Christuna, sorry to hear that, we haven't had any issues with this clutch but we'll have engineering check it out anyway. Would you happen to still have it? Please PM us your purchase details (date, retailer, order number) and we'll be happy to send you a warranty replacement.

I have not bought the Uro fan clutch, but I have bought other Uro brand parts and my personal experience is that the majority of the parts that are in high stress/load locations fail prematurely, usually within a few months. I think the OP would be better off getting a used OEM brand clutch instead of a new Uro brand.

I purchased the URO fan clutch it is arriving tomorrow. I see that there is a Behr one available for $90.

The parts arrived today.

I ordered a URO fan clutch and a FEBI 9 blade fan as my fan was the older 11 blade type.

I do most of my own work however was thinking of having a Mercedes mechanic I know do this job. Should I proceed with the URO fan clutch or purchase a Behr or other. Even if Uro back up the part the labor is costly.

????

Seeing that you could do that job yourself, I would get a better quality fan clutch and skip the cost of having a mechanic do it. On my 201, I'm able to remove and install a fan clutch without taking or emptying out the radiator. The m103 in the 201 is probably the most restricted to work on front engine bay wise.

I did a bit of research on doing this job. The part I was not confident about was how to hold the fan clutch when removing and installing the fan clutch. I see that there is a tool that is available, it is a rod with a bent end. the bent end of the rod goes into a hole in the water pump pulley? and the rod gets inset into a slot in the water pump housing. I could buy the rod and mess with it all but am looking to have some other work done at the same time and might only get charged and hour or less for the fan clutch job so was thinking of just going for it.

Long 3mm or 4mm hex key works fine. However, do whatever you feel is your best option, but use a better quality clutch. For critical parts always use the best quality. Something like an interior trim piece or something that is of no significant importance if it fails, you could try saving a few dollars by going with the unpopular brand. Just my 2 cents. Good luck.