Loud Knocking
Thread Starter
Newbie
Joined: Apr 2016
Posts: 9
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From: La Puente
2005 Mercedes-Benz C320
Loud Knocking from AC Compressor.
Okay so this is my second post here and I am having a bigger problem than my first post. I was driving today and suddenly my engine starts to knock I pull over and it stops but when I rev it the sound comes back and will be gone after a minute at idle or something. Also when I turn the car off and wait a minute and start it back up its gone but rev it again or drive and its back. It is a really loud knock and any input well help. I'll record a video and post it tomorrow since it is dark right now.
My car is a 2005 C320. M112 engine I believe.
My car is a 2005 C320. M112 engine I believe.
Last edited by kevinthenegro; Jul 16, 2016 at 01:43 AM.
MBWorld Fanatic!
Joined: Aug 2015
Posts: 1,059
Likes: 73
From: DC Metro Area
2007 Mercedes E550
Okay so this is my second post here and I am having a bigger problem than my first post. I was driving today and suddenly my engine starts to knock I pull over and it stops but when I rev it the sound comes back and will be gone after a minute at idle or something. Also when I turn the car off and wait a minute and start it back up its gone but rev it again or drive and its back. It is a really loud knock and any input well help. I'll record a video and post it tomorrow since it is dark right now.
My car is a 2005 C320. M112 engine I believe.
My car is a 2005 C320. M112 engine I believe.
The usual suspects are spark plugs or a dirty mass air flow sensor. All quick fixes. Might also add Lucas fuel injector cleaner to gas tank to increase octane level and thereby decrease knocking. Feel free to pm if you need help.
Thread Starter
Newbie
Joined: Apr 2016
Posts: 9
Likes: 0
From: La Puente
2005 Mercedes-Benz C320
Do you have a check engine light? If so, what code are you getting?
The usual suspects are spark plugs or a dirty mass air flow sensor. All quick fixes. Might also add Lucas fuel injector cleaner to gas tank to increase octane level and thereby decrease knocking. Feel free to pm if you need help.
The usual suspects are spark plugs or a dirty mass air flow sensor. All quick fixes. Might also add Lucas fuel injector cleaner to gas tank to increase octane level and thereby decrease knocking. Feel free to pm if you need help.
MBWorld Fanatic!
Joined: Aug 2015
Posts: 1,059
Likes: 73
From: DC Metro Area
2007 Mercedes E550
It doesn't sound like a problem with engine, plugs, coils. It seems like something is loose?
Junior Member
Joined: Dec 2015
Posts: 54
Likes: 1
From: Kirkland, WA
2003 C230 kompressor
That sound would drive me bonkers. Are one of you pullies vibrating? Is the serpentine belt tight? Sounds like it's coming from a belt? Have you looked under car? Does the sound change as you press on accelator?
It doesn't sound like a problem with engine, plugs, coils. It seems like something is loose?
It doesn't sound like a problem with engine, plugs, coils. It seems like something is loose?
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Thread Starter
Newbie
Joined: Apr 2016
Posts: 9
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From: La Puente
2005 Mercedes-Benz C320
Sorry for the late reply, my computer needed to be rebuilt. You guys are absolutely right, several hours I posted the video I actually did find out that it was my AC pulley. I didnt want the car to be driven like this so I drove to AutoZone and as soon as I pulled into the lot the pulley completely stripped and was starting to smoke due to the friction. I bought a smaller belt to bypass the AC compressor and they were nice enough to let me borrow their tools to change the belt. Now there is no more noise, but the inside feels like I am being baked now. You guys have been a great help and I cant take you enough for the input.
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Thread Starter
Newbie
Joined: Apr 2016
Posts: 9
Likes: 0
From: La Puente
2005 Mercedes-Benz C320
I also changed my motor mounts and transmission mount after this since it was vibrating sometimes and may have caused this. Did it myself for only $150 and now the ride feels smooth.
