Strange Engine Noise While Braking...
Thread Starter
Junior Member
Joined: May 2010
Posts: 25
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1999 Mercedes ML430
Strange Engine Noise While Braking...
Ok, this is a rather strange problem and a little hard to describe. My ML430 just started making a horrible engine grinding/rattling noise while I'm at stop lights. The vibration and noise is all coming from the driver's side of the engine. The sound/vibration is similar to the sound it makes when braking down hill very slowly, except much worse.
When I pull up to the light and sit for about 15 seconds, this noise will occur and last about 5 seconds. If I remain at the light for up to 40 seconds, the noise will occur again longer and more severe sounding. It only does this when on the brake at a light, in gear, and not when the engine is just idling.
I have attached a zip file with a audio clip of this noise I made earlier. The first sound starts at 13 secs, and the second, worse sound comes in at 42 secs. Please listen to this clip and let me know if anyone has any suggestions on what this could be. I've never heard of this before. Thanks in advance!
When I pull up to the light and sit for about 15 seconds, this noise will occur and last about 5 seconds. If I remain at the light for up to 40 seconds, the noise will occur again longer and more severe sounding. It only does this when on the brake at a light, in gear, and not when the engine is just idling.
I have attached a zip file with a audio clip of this noise I made earlier. The first sound starts at 13 secs, and the second, worse sound comes in at 42 secs. Please listen to this clip and let me know if anyone has any suggestions on what this could be. I've never heard of this before. Thanks in advance!
Thread Starter
Junior Member
Joined: May 2010
Posts: 25
Likes: 0
1999 Mercedes ML430
Low Side Pipe Vibrating?
Ok, I think I narrowed this issue down today. It seems that the A/C low side pipe is vibrating periodically and causing this vibration noise. I did just recently evacuate the system and replace the expansion valve and recharged the system, but I do not see any difference in cooling or fan speed when this vibration occurs.
Does anyone know what would cause this low side pipe to vibrate like this and create such a sound? Please let me know if you can.
Does anyone know what would cause this low side pipe to vibrate like this and create such a sound? Please let me know if you can.
