HAs anyone ever noticed a whining noise from the engine compartment.
It's very evident with windows open, but can still be heard with a/c on and windows closed. Thanks for any info.
2003 E500 52k miles

 

You could have...

1. Low steering fluid

2. Noisy A/C compressor

3. Noisy upper idler pulley.

Internet diagnosis predicts a %70 chance that it is #2.

 

Or possibly the belt. Check for cracks and/or "shiny" contact surface. No % prediction.

 

Have you opened the hood to check it out?

 

No. 100% Prediction.

 

The steering fluid is ok.
The noise is present with A/C Off.
The belts look Ok. The SA at MB said its normal , but on my E320 its definetly not there.
Finally. I did open the hood to check it out!

 

SBC pump... thats my guess

 

I had that same problem too, I took it to the dealer and they couldnt find the problem but they went ahead and replace the water pump and belt (that's what they said). After that the problem was gone!!!

 

But Jram you have a completely different car (or do you also have a w211?) and I can't imagine
any dealer replacing a water pump when they can't determine that that's the source of the problem.

 

Sorry I wasn't clear, I have the C280 with extended warranty. The dealers always have some excuse "nothing is wrong". So for second time I took it back and I insisted and pushed to get it fix and so they replaced the belt and water pump because they (assume) that could be the problem. When I got the car back the noise was gone. So afterwards the Service Tech told me that was the problem... Funny they couldn't located the problem inthe beginning...

 

i also have the same problem they said its nothing wrong but its a water pump..
do you have any idea how much does it cost to replace it
thank you

 

I often hear a "WOOoooooooo" sound which fades in around 30 MPH & fades out at somewhat higher speed. I believe its when the car is cold only. It has been there since new, and other than fading in & out, its pitch & volume is not RPM, Speed or direction dependent... just its fade in & out... it continues to "wooooo" even if I lift my foot off the gas. If I had to guess, I'd say its under the car somewhat towards the mid/ rear. Its still a mystery to me almost 3 years later.

 

You must have a Banshee under the car ; it probably got stuck in there while the vehicle was being built.

 

Could be any of these and including SBC pump.

However my $$ is on #3. I changed my belt at 85,000 miles and the idle pulley was rough. I was suprised to find on inspection from opening the bearing there was no lube left in the bearing.

(Mounted the pulley in the lathe then pressed the bearing out for the inspection). This failure is common but might not be the source of noise.