04 ML350 squealing on acceleration
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2004 mercedes ml350
04 ML350 squealing on acceleration
I have a squealing issue with my ml350 that I cant seem to figure out. It runs, drives, and stops, like new. No braking, shifting, handling, or power issues. It only happens when I am accelerating. It doesn't make any noise if I am holding a constant speed. Doesn't matter if I am turning left or right. It doesn't make the noise if I am parked and stepping on the gas. It doesn't squeal right away if it has been sitting for a while but never takes very long to appear. Sometimes I have to accelerate hard to make it squeal, while other times it happens if I barely press down on the pedal. Speed does not affect the pitch, loudness, or frequency, of the squeal. It does not squeal in reverse. It seems to be coming from the front but I am not sure.
The squealing started after I replaced the pads and rotors but I am not convinced that this is the cause since it only happens while accelerating. The only reason I replaced the pads and rotors is due to 1 warped rotor that was pulsing while breaking. I am the type of vehicle owner that will replace all 4 even though only 1 is bad.
I am meticulous about maintenance on my vehicles. 
It is never taken off road, never used to haul heavy stuff, never driven hard.
I cant think of any more details off the top of my head. I tried using the search and could not find anything that was remotely close to the issue I am having. Thank you in advance.
04 ml350
143k miles
new pads and rotors all the way around (meyle)
new belt (gates)
new idler pulley (oem)
new tensioner pulley (oem)
fresh gear oil in front and rear (royal purple)
fresh transfer case fluid (royal purple)
fresh oil change (Mobil one)
Giovanna wheels (much lighter than stock wheels)
The squealing started after I replaced the pads and rotors but I am not convinced that this is the cause since it only happens while accelerating. The only reason I replaced the pads and rotors is due to 1 warped rotor that was pulsing while breaking. I am the type of vehicle owner that will replace all 4 even though only 1 is bad.
I am meticulous about maintenance on my vehicles. It is never taken off road, never used to haul heavy stuff, never driven hard.
I cant think of any more details off the top of my head. I tried using the search and could not find anything that was remotely close to the issue I am having. Thank you in advance.
04 ml350
143k miles
new pads and rotors all the way around (meyle)
new belt (gates)
new idler pulley (oem)
new tensioner pulley (oem)
fresh gear oil in front and rear (royal purple)
fresh transfer case fluid (royal purple)
fresh oil change (Mobil one)
Giovanna wheels (much lighter than stock wheels)
Thread Starter
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2004 mercedes ml350
Thanks for the quick response. Checked the backing plates. They aren't touching. If it was a stuck caliper wouldn't it squeal all of the time except when braking? Mine only squeals on acceleration. I will check the calipers tomorrow.
MBWorld Fanatic!
Joined: Oct 2011
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From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
The squealing is probably present but not audible to you except at higher speed.
You must clean the areas on the caliper with a rigid wire brush where the brake pads fit into (red arrows).
After cleaning, apply a small amount of Copper Based Anti-Seize paste to those areas on the caliper.
You must clean the areas on the caliper with a rigid wire brush where the brake pads fit into (red arrows).
After cleaning, apply a small amount of Copper Based Anti-Seize paste to those areas on the caliper.
Thread Starter
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2004 mercedes ml350
Speed doesn't affect the noise. It will squeal at any speed.
Took everything apart and cleaned it with a wire brush and applied copper anti seize. It is still squealing.
Any other ideas?
Took everything apart and cleaned it with a wire brush and applied copper anti seize. It is still squealing.
Any other ideas?
Senior Member
Joined: Mar 2002
Posts: 282
Likes: 5
From: Brisbane, Australia
2002 ML320, 2003 A160
Check your engine mounts. Have they ever been replaced?
One of the things that happens only when you accelerate is the torque of the engine makes it rotate clockwise on its mounts. If the LH mount fails (which is subject to the most tension - the RH mount gets compressed), the left front corner of the engine will sit up. This could cause rubbing by a component that rotates at a constant speed compared to engine RPM or wheels. Like anything driven by the serp belt, including the fan, alternator or AC compressor.
One of the things that happens only when you accelerate is the torque of the engine makes it rotate clockwise on its mounts. If the LH mount fails (which is subject to the most tension - the RH mount gets compressed), the left front corner of the engine will sit up. This could cause rubbing by a component that rotates at a constant speed compared to engine RPM or wheels. Like anything driven by the serp belt, including the fan, alternator or AC compressor.
Last edited by DrX; Jun 2, 2017 at 03:36 PM.
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MBWorld Fanatic!
Joined: Oct 2011
Posts: 7,107
Likes: 765
From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
