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Discussion Starter #1
Hello All,

I've just gone through the cooling system on the $700 190e 2.6, both electric fans, the fan resistor, and the engine driven fan clutch were replaced. The A/C is arctic cold now and engine temps are pegged right where they should be.

Question - I replaced the engine driven fan clutch with the "Uro" branded clutch, which in appearance was identical to the OEM unit. However, ever since doing this, I can hear the loud whir of the fan at all times, at all engine RPM. I'm used to these viscous clutch fans making a lot of noise as RPM increases, and then speed bleeds off unless the air through the radiator is higher than the temp that the clutch is designed for.

This is happening even when it is cool outside. I don't think this is right, and it's probably not going to make fuel economy happy. Do you all think I have a bad replacement part? I think this was about $50.. I can go for the Meyle branded OEM unit from FCPEuro for about $84, or I can just try another Uro - I'm just not sure if there's a problem with their design, or just my unit. Would love to know if anyone else has used the Uro unit on a 2.6.

Thanks!
~Bryan
 

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I’m afraid I’ve purchased URO parts in the past. They do not have a good reputation to most people on this forum. It is because their products tend to fail quickly as I understand. I’m afraid yours may be defective. It is thermo sensitive as I understand, so hot engine makes it turn. Cold start in the morning it should not be turning, if I’m not mistaken.
 

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I assume you will not take the car to tahoe, so does it really matter? With a working fan clutch car warms up around here in 3 minutes. Does it matter if it takes 4 min?

- cheers!
 

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I'm not aware of it being an issue on MBs, but on older BMWs when the fan clutch fails and constantly engaged the fan would have a tendency to lose blades at high RPM.

For the cost of fan clutches I would look into installing a SPAL electric fan. Should be easy to retrofit as there are a number of places to get a temp signal from.

And here's another option to repair the old clutch:


 

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It's supposed to slip at around 3500-4000 rpm. Fwy cruising rpm is a bit less than that, so the fan is unnecessarily blowing at those speeds. This is one downside of mechanical cooling. It's designed to keep the temps sufficiently in check sitting stationary at idle and cruising around, and so at speed there is greater parasitic loss. Same is true for both fans and water pumps.

I'd probably not go so far as to convert to an elec water pump, but if/when the $20 MTC brand clutch I got from a friend last year fails I'll definitely put in an electric fan and never have to worry about it again.
 

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I still prefer the Mercedes way of cooling fans. Mechanical + Electric for safety.
The electric only ones generally fail because of relay's etc eventually.

The clutch fan in my car is still original and I just checked again is working fine after 30 years.
Not sure what the trick is for longevity, I assume pure luck, or maybe road conditions (humidity/dust)

- Cheers!
 

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The redundancy is a great idea for a failsafe, but the typical failure is the fan clutch - more common than electric fans. And if/when it fails it's doing fuckall for cooling which is no better or worse than a dead electric fan.

Other than for purity and KISS principle sake (not without their merits), I don't see much of a benefit to replacing a failed fan clutch over retrofitting an electric puller fan.
 

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I like the idea of the engine coolant running at 90c +/-5c at all times.
If the Electric fan plus an auxilary fan as back-up will do that with 30+ year reliabilty, I'm all for it.
It also has to fit in this tight space.

I like the later model electric fans that stay on a little after the car is turned off so that the coolant trapped in the engine channels do not shoot up to 105-110c after the engine is turned off after a long run on a hot day.

Actually even the aux fans can be driven that way to help a little even though they are on the wrong side of the radiator.

Reliability and long term life wise though, I think the clutch fan is longer lasting then the electric system.
I've had 2/4 saabs that boiled over (one at grape vine ramp, the other at sunset blvd at fairfax) when they were less than 20 years old, back in the day.

So I was very pleased that Mercedes had a much improved cooling back in '89. And as I was saying not even once has the car boiled over let alone run at >100c

What's missing in the clutch fan is a way to test them properly/scientifically. A strobe light meant for checking the timing may work. I think I will try that later. Just to check if it is keeping up with the engine rpm's and also cutting off at high rpm's.

If one converts to an Electric Fan though one should add that post shut off cooling capability and one would have to beef up the alternator as the alternator on our car's can not take an additional >20A of drain in my opinion.

- Cheers!
 

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Discussion Starter #10
Thanks to all - sounds like the Uro fan clutch just does not meet the spec - I'll grab a better brand here and replace it - then she will be nearly perfect, mechanically!
~Bryan
 
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