Does anyone know if I need a special tool to change the fuel filter or what size wrenches? Also, how long should a filter last? I have 165,000 miles but am unsure of the last change or if there was one.

Secondly, I have fan problems that seem common. My first fan stopped working so I replaced it with another used one I bought on E-Bay..I know I know...but it was only 20 dollars so I thought it might be worth a shot. It worked for two days and stopped. It just free spins and doesnt lock up when it is supposed to.
Also, niether of the auxilarary fans come on when they should. I replaced the sensor (new from Mercedes) and inspected all the wires and resistor.
The fans do engage when the AC is used, so I know the fans themselves work. Im lost on this one.

Please help! Im at wits end with the fan issue. Its around 100 degrees lately and the only way for it to stay moderately cool is to be in motion.

Thanks guys!

EDIT: Upon further thought (see lower posts)






DON'T DO WHAT IT SAYS BELOW






(I've just left it there for posterity)



I think your fan clutch needs replacing. Try this - when the car is running, try to stop the fan with your hand - BE VERY CAREFUL. Basically, if you are able to stop the fan with your hand, the clutch isn't doing its job. The way my mechanic put it was "I shouldn't be able to do this, the fan should take my hand off". Obviously the car should be nice and hot - 100 C or so for this test to be valid. Again, be careful and do this at your own risk.

The fans come on low speed when the AC is at operating pressure, it takes mine about a minute for mine. They come on high speed when the engine gets over 106 deg C, that is controlled by a variable resistance sensor located about a third of the way from the back of the engine on the top of the cylinder head tucked between the valve cover and the air filter. The signal goes through the climate control in the dash (don't ask me why) which has the relay. Hi/low goes through a power resistor bolted to the body just to the left (looking towards the back of the car) of that AC cylinder thing with the sight glass on top (forget what its called).

__________________
5 speed '91 190E 2.6 320,000 mi. (new car, fast, smooth as silk six, couldn't find any more Peugeots)
5 speed '85 Peugeot 505 2.5l Turbo Diesel 266,000 mi. (old car, fast for a diesel, had 2 others)
5 speed '01 Jetta V6 (new wifes car, pretty quick)
5 speed '85 Peugeot 505 2.2l Turbo Gas 197,000 mi. (wifes car, faster, sadly gone just short of 200k )
5 speed '83 Yamaha 750 Maxim 14,000 mi. (fastest)
0 speed 4' x 8' 1800 lb Harbor Freight utility trailer (only as fast as what's pulling it)

STOP, DANGER...
That is NOT a safe way to test the fan clutch...
* If there are sharp edges on the blade, it will slice you open.
* If there are serious cracks in the blade, it can shatter and slice you.
* If the clutch is seized to the shaft, it will not stop...

Use compressed air or a garden hose, spraying against the fan rotation.
The attached drawing should make the procedure clear.


Have a great day.

Attached Thumbnails

 

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Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
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Technical Quality Auditor.
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1985 300SD
1983 300D
2003 Volvo V70

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People forget how dangerous it can be when working on cars. A damaged fan can send metal through the hood if it breaks, now think what it can do to your hand......

Please be carefull.

Umm sorry??? But that's what my mech did. He just reached in and stopped it with his hand. but I guess he could already tell that the clutch was gone, so he was just demonstrating.......

I don't quite understand the garden hose method - does that actually stop the fan???

I know your mech did it, and he got very lucky.

You don't have to even rev the engine very much to get a piece of metal through the hood. I always stand away from the fan even when checking ignition timing.