300E Whirring - Transmission Pump?
 

Hello all,

Vehicle: 1992 300E 3.0L AT 122k

Problem: Last night while tooling around town a loud, rpm dependent whirring noise developed. It is present in all gears including park and neutral. This morning when I started the car the noise was still present. I got my trusty stethoscope and began listening. Unfortunately, when I placed the stethoscope on the transmission dipstick tube the noise was very loud and there was a lot of high frequency vibration in the tube. The fluid is to the proper level and clean. The filter has been replaced within the last 10k.

Threw caution to the wind this morning and decided to drive the car to work. Low rpm in gear cause the noise to get louder. Other than the noise the car drove beautifully and shifted perfectly.

Questions: Has anyone had the transmission pump fail with only 122k? Did it make a whirring noise? Are there other parts of the transmission that can make this sort of noise?

Thanks in advance for your help.

could be fan clutch!

Maybe the starter bendix gear isn't fully retracted?

Maybe something got through the bell housing mesh and is hitting the torque converter?

Sixto

RPM dependent noise in park is not likely to be tranny
 

I would startwith belt-driven accessories. Don't forget the alternator - the brushes can wear out by 120K miles.

Another listen...
 

I took another listen with the stethoscope. All of the belt driven accesories are relatively quiet running with the exception of the air pump. However, the noise definitely sounds as if it coming from the rear of the engine compartment. Also, the noise is definitely loudest on the transmission dipstick.

The reason I believed the transmission pump was the failing part was because it does "whir" in park. Does the pump not spin when the transmission is not engaged into a gear? Would belt driven accesories change the sound when shifting from park to reverse (more than would be appropriate with the rpm change)?

As a diagnostic step, can anyone advise as to the wisdom of running the car with the polybelt removed?

How would one check if the Bendix gear is not disengaging?

From your description of the noise it sounds like a plugged filter. Did you personaly see the filter being changed, if the answer is no, change the filter. The pump turns when the engine is turning.

I don't think it's a problem running without a belt for a couple of minutes with a cold engine.

Sixto

Dead Tranny...
 

Well, I took the belt off and the noise was still present.

After removing the transmission my Mercedes rebuilder confirmed that the pump is in fact bad.

I think I am going to replace it with a low mile used part from ebay.

Thanks all!

New problems....
 

Well, got a nice used transmission here that looks really similar to the one out of my car, but....

the used transmission is from a '90 my car is a '92, and...

there is a solenoid mounted to the bell housing on the used transmission that my car does not have. Does anyone know what this solenoid is/does?

Part # 158 in the diagram...http://detali.ru/cat/oem_mb2.asp?TP=1&F=124030&M=103%2E983&GA=722%2E35%5F09C&GM=717%2E433&CT=GA&cat=09C&SID=27&SGR=045&SG N=03

Does anyone know whether the '90 to '92 transmission is a direct swap?

Thanks for your help!!!!

Update
 

I believe the part numbers are:

Used trans - 722.358

My trans - 722.359

Thanks again.

That is one style of the up shift delay for the catalyst converter, take it off #144,155,161,158 and use the plugs from the original transmission. If you leave it on the transmission with not shift.

Thank you so much C32 AMG!

I was hoping this was the case. I will go ahead and install this transmission, and hopefully, be back on the road soon. Wish me luck.

Does anyone need a catalayst shift delay solenoid?

Back on the road again.
 

Took this opportunity to do some major work on the car.

After switching out the tailshaft housing (exhaust mounts broken), shift cable assembly, and new seals at the ends, I installed the new transmission.

I also replaced the front guibo, water pump, front and rear crank seals, camshaft seal & housing gasket, and valve cover gasket.

I happy to say that the car is driving better than ever. Thanks to all those that helped along the way!