I have a 99 clk430. A couple weeks ago, I discovered a whine that you would hear if you were sitting still and reving the motor. I had it checked out and we first thought waterpump since it showed signs of leaking. We replaced it and while doing so, noticed the tensioner pulley had quite a bit of play. So we replaced it. The whine was still there. Next we thought was the power steering pump since it too was showing signs of beginning stages of a leak on the lower side. When you would turn the wheel all the way to the right or left and then force it a bit further, the noise would alter. So we replaced it. The whine seemed to be not as bad, but is still there. The mechanic stated that most ps pumps that he had replaced had usually come with a note stating that since they were shipped lubricated, there may be a slight whine for a few days until the pump had been used. Has anyone had this same problem and can you help me resolve it? The car now has a new waterpump, tensioner pulley, and ps pump. Both pumps were leaking, so I don't feel I have thrown money at something when I shouldn't have, but the whine is annoying. To describe the sound, it sounds like when the ps pump is low on fluid, but you don't have to be turning the wheel to hear it. You can sit perfectly still and just rev the motor and the pitch of the whine changes. Thanks in advance to anyone that can help me.

 

Hi i too have this problems some days worse than others usualy in the morning hasnt been cuz its been hot outside on mine though i think it might be an engine berring which u can guess is expensive to replace...

 

Hi Scott66fish,

Go to the auto store and buy yourself an "automotive stethascope" for under $25. It looks like the one the doctor uses to listen to your heart...except cheaper. Place the tip on any alternator case, pump housing, head near the cam etc, and you WILL be able to hear the bearings roll, the valves click, the piston rings sliding etc.
Place the tip on every suspect device; you will clearly know when you found the one making the noise. Warning: dont get the tool caught in the fan belt while the engine is running. It will be in the instructions.

Blue

 

Thanks for the good info my fellow Benz friends. I have, however, been with the mechanic who had a similar tool that before we replace the ps pump, even let me listen and the noise did sound like it was coming from the ps pump. I have often wondered if maybe one of the pulleys associated with the pump may the culprit. I had my engine and tranny checked back at the first of the year and found a bearing loose in the tranny which ended up costing a bundle to fix, but this is a different type noise. It doesn't matter whether the car has been sitting, driven all day, moving, or just idling, the noise is there mostly when you rev the motor. Thanks again for all the help.

 

From my experiences, this noise almost sounds like the internal screen of the power steering reservoir has been damaged/torn causing the whining. If it is bad enough you will hear it even without turning the steering wheel.

If you didn't replace the reservoir during pump replacement, I would check that.
You can also inspect it - engine running - by removing the cap and checking to see if the fluid is "swirling rapidly" or being "agitated" (sp?) [i.e. air being mixed with fluid].....

Just a thought.

 

Have you tried running the car without the serpentine belt for five minutes only? If the noise stops, then you knowit is one of the remaining accessories making the noise, and NOT an internal engine bearing.

Blue

 

Benztec, I have checked the resevoir with the car running and the fluid seems to be just standing. There is no swirling. What would your feelings be on this? The noise really seems to be external from the main engine. It sounds like to me it is coming from the ps pump area. Any thoughts?

 

Sorry about the delay in replying. I was out of town.

I would go in the direction as 'Blue' indicated. Take off the belt and run the engine.
Couldbe a pulley noise....i.e. idler pulley. They have had their share of issues with idler pulley noises.

Good Luck.

 

I was in to see the mechanic again yesterday and we still think it is coming from the ps pump. I checked and the idler pulley was indeed changed with a new one when I had the water pump and tensioner pulley replaced. I have tried lucas ps fluid in and this morning it seems a tad quieter, but if history repeats itself, it will probably get louder again in a day or so.