S500 Noise When Accelerating
 

2001 – S500

I’m hearing a noise from the front passenger side under the hood. The noise starts when I start to accelerate (moaning noise). When car is in Park or Neutral its fine as soon as I start to accelerate the moaning start and seems to disappear when I start to hit 50 MPH. Anything above 50 and its fine. When the car drops below 50MPH the sound comes back.

Belt tensioner or motor mounts possibly although left motor mount is usally the first to go bad.

You can rule out the tensioner, idler pulley and damper (shock) by dropping the belt and running a COLD engine for NO more than 30 seconds with the belt removed.

No LUCK, When I press the gas pedal I start to hear the noise. I can have the car in Park as soon as I press the gas pedal the noise starts. It goes away when I start hitting about 50mph. Its a whinning and moaning noise.

If you pulled the belt and ran it you've ruled out the tensioner and all accessory devices being the culprit. If you ran it at 50mph with the belt off you ought to have gotten a CEL......

Next I'd look at the motor mounts. You can use a floor jack and large rubber bushing and lift the bottom of the engine 1/4" to take the weight off the mounts and see if the noise disappears or measure them from below to see if they have collapsed. Dont lift more than 1/4" or YOU will damage the mounts.

Hi didonato, is this the same noise you referred to in your earlier thread (ABC fluid leak, etc), or something different? By the way, how'd you make out with the ABC problem?

Same noise, Dealership said its not the ABC making the noise. I took it to my local Mech. and he thinks its the pump for the converter. He said the pumps in the transmission. I'm not sure if I'm even using the right terms. He said that the job is over head to perform. I hate taking back to the dealer again. Any suggestions??

Going back and forth between the dealer and your local mechanic seems to be a waste of your time. So far, the dealer has told you what the noise isn't , and the local guy has told you what he thinks the noise is, but doesn't want to get involved!

It's simple. Let the dealer diagnose the problem. If they're wrong, don't worry about it. Let them know that you're not going to pay for them to guess. Tell them that you'll gladly pay for a proper diagnosis, but you won't pay them to "try this or that and see what happens". Let us know what happens.