Engine fan fell off my W201 - PeachParts Mercedes-Benz Forum

crhenkel · #1 06-13-2007, 10:38 PM

Ok, so first, the car is really in very good condition. Now, the bad, the engine fan was making some extra grinding noise and before I could determine the source, the engine fan, visco clutch and the pulley actually fell off the engine. I have not looked at it too much, it happened tonight and it is dark. Can anyone give me the basics on how the fan is attached to the engine by the water pump shaft, what might have gone wrong and what I have to do to put the fan back on the car. I would guess I just need to completely replace the water pump. Ick. I am guessing that there is a bearing the pulley shaft was on that is pressed on to the water pump shaft and it siezed and the rest is history. Please help, I can do the work no problem, but I have never really thought about how the fan is attached to the shaft of the water pump and that it could actually just break or come off... Any guideance on how to change the water pump? The car is not leaking any water even thought the fan fell off. Weird

yal · #2 06-14-2007, 12:42 PM

Should look something like this. Piece on the far right (#35) is a bearing bracket...its probably what fell off taking everything with it.

crhenkel · #3 06-16-2007, 01:34 PM

YAL, yep that is the piece. I heard the noise and assumed it was a water pump going bad and I would have time later, dont drive car much, selling it. Then after it fell off, I figured time to quick do the water pump, only to find it is the fan clutch bearing bracket, which I had a heck of a time finding, couldnt find it in stock online, had to do reman from MB for $130. DId finally find it for $110 at Arizona autohauz parts, but I already ordered from MB will be here in two days.
Can you tell me how to check the fan clutch for operation? I am curious if a bad fan clutch might have killed the bearing. The fan clutch is more $ than the bearing bracket.

crhenkel · #4 06-16-2007, 01:38 PM

THe shaft from the bearing bracket is still attached to the pulley and fan clutch. The bearing in the bracket is destroyed and gone. THe bracket stayed on the car, with no bearing or shaft. The fan and clutch and pulley must have spun around and then stopped in the engine bay sandwiched between the radiator and the front of the engine block, somehow managing to NOT damage anything else, including the radiator. SUper Lcuky nothing else got damaged.

yal · #5 06-16-2007, 08:35 PM

WOW!

Thats pretty lucky it didnt damage anything else.

And now for the a technical break to explain the clutch...

"A spring, which is responsive to centrifugal forces generated by rotation of the driving member, holds the belt in driving engagement with the driven member when engine speeds are below a predetermined level, but yields to permit the belt to move out of engagement with the driven member when engine speed exceeds the predetermined level. A temperature responsive capsule includes a lever which holds the spring in a position maintaining engagement of the belt with the driven member when the temperature level exceeds a predetermined level, regardless of engine speed."

Basically if the engine rpm is below a certain level it locks. If the temperature goes above a certain temp it locks.

crhenkel · #6 06-17-2007, 02:28 AM

So, if I understand correctly, when the car is idling in the driveway, the fan SHOULD be turning and the clutch is engaged under the "low rpm" concept needing more air cause the car is not moving or not moving fast. If the car is moving fast, ie high rpms, the car is typically expected to me traveling fast enough to provide adequate air flow...unless the engine/radiator is still putting off enought heat to engage the clutch, over riding the high rpm clutch cut out. Is this about right?
I was under the belief that the clutch was only temp sensitive and it should let the fan swing free until the engine was hot enough to activate it. i was concerned the clutch was bad when at idle the fan was spinning like crazy.

If all this is correct I see why they changed the design from my 16v with the electro magnetic clutch. The visco clutch is a more simple way get fan at low speed and at hot temps but let is free wheel at low temp and high speeds when it is not needed.
SO if the fan clutch is ok to spin at idle ( the opposite of my 16v) how do I decide if the clutch is good or bad. I figure a bad clutch might be a good reason the fan clutch bracket bearing went bad.

yal · #7 06-17-2007, 12:54 PM

Its a great design. My 2.3 has the electro magnet fan too which can rob power in stop and go traffic. The clutch fan on the 2.6 is really elegant.

Best way is probably to test the full lock up capability when the fan heats up at 100C on the temp gauge. The low speed lock up is weak, its just enough to keep the engine cool in idle situations.

crhenkel · #8 06-17-2007, 07:29 PM

Thank YAL, I'll give it a test tomorrow after I get the fan mounted back on the car, the bracket should be here tomorrow morning.
Thanks