2005 S500 Loud Humming
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2005 Mercedes S500
2005 S500 Loud Humming
Hi all - noobie here. Bought a 2005 S500 for my father with 70k miles for $8000. The car was excellent and we loved it for the first two weeks.
A few days ago, we noticed a loud humming sound when driving and slowed down or at stop. As of today, the noise has gotten louder and we also noticed there is now sluggish acceleration.
No warning lights—just the noise. When the noise is at its loudest, turning the AC off seems to lessen it. It is so loud that we can hear it in the car with the doors and windows up.
Any thoughts would be appreciated. No idea where to start!
A few days ago, we noticed a loud humming sound when driving and slowed down or at stop. As of today, the noise has gotten louder and we also noticed there is now sluggish acceleration.
No warning lights—just the noise. When the noise is at its loudest, turning the AC off seems to lessen it. It is so loud that we can hear it in the car with the doors and windows up.
Any thoughts would be appreciated. No idea where to start!
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Joined: Dec 2012
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From: Ball Ground, GA (N of Atlanta)
2003 S500 2007 GL450
First effort should be to locate the source of the noise. One way to do that is to get a piece of 1/4", 5/16", or 3/8" (convert if you are metric) rubber or plastic tubing about four feet long. With the engine running and hood open, place one end of the tubing in your best ear. Use the other end of the tubing as a probe to locate the source of the noise. Stay well out of moving or hot parts!
Simply having the open end of the tube near the noise source should give a noticeable change or increase in the noise level thru the tube. Touching (safe, non-moving) parts with the open end can also help to determine the source. Check around the AC compressor, which is located down low on the left side of the engine. (Remember that left/right on a vehicle is always defined from the viewpoint of the seated driver, so the left side of the engine will be on your rights as you stand in front of the car.) Another common noise source is the belt and pulleys, especially the idler pulley.
Determining what affects the noise is also helpful. Does the noise change with engine speed, or with road speed, or neither?
Is the noise coming from the engine compartment? Or from the dash area? Or the vents? Does the noise change with blower speed?
None of us can give you a magic answer - only you are there to listen and determine the source...
Simply having the open end of the tube near the noise source should give a noticeable change or increase in the noise level thru the tube. Touching (safe, non-moving) parts with the open end can also help to determine the source. Check around the AC compressor, which is located down low on the left side of the engine. (Remember that left/right on a vehicle is always defined from the viewpoint of the seated driver, so the left side of the engine will be on your rights as you stand in front of the car.) Another common noise source is the belt and pulleys, especially the idler pulley.
Determining what affects the noise is also helpful. Does the noise change with engine speed, or with road speed, or neither?
Is the noise coming from the engine compartment? Or from the dash area? Or the vents? Does the noise change with blower speed?
None of us can give you a magic answer - only you are there to listen and determine the source...
