Rod knock?

Sshec152 · 07-31-2016, 06:30 PM

A couple of weeks ago i was sitting in the drive through when i heard a metallic tapping/knocking noise. Its not always constant, it wont do it during a cold start until the rpms drop to a normal idle, i can be sitting idling and all of a sudden it will make the noise and randomly go away. I found that if i drive for a while on the highway then come to a stop it will take a while until it does it, and i also found that if it does it while im sitting still and i turb the wheel slowly it will basically dissapear. The noise will speed up with revs until about 2500rpm then go away. Im not sure if its rod knock, lifters, etc. I also have a lightweight flywheel that generates slight gear chatter but this noise doesn't go away when i push the clutch in. Vehicle has 101K

stashtrey · 07-31-2016, 06:48 PM

That doesn't sound very promising. Wish you the best of luck getting it figured out and it's not what you think it is.

Jeff@TopGearSolutions · 08-01-2016, 11:11 AM

I'd normally say that motor is toast but if it goes away maybe something is just loose, get under the car and start checking connections on stuff, first.

maaaaackle · 08-01-2016, 12:42 PM

It sounds like rod knock to me. does the noise get faster as you get on the gas?

Just to be absolutely sure I would make sure your nothings loose under there...

Sshec152 · 08-01-2016, 05:53 PM

The fact that it goes away is the only hope i have right now, im gonna drain/check the oil and see if anything is loose, the sound is more prominent on the driver side but i still have not been able to pinpoint it. Anything over there that could possibly cause that noise? I also recently replaced my serp belt, tensioner and p/s pulley with the ecs one because my oem one was broken. Ive heard of the tensioner making that noise so i will also check that and report back!

agustincuenca · 08-01-2016, 11:02 PM

I can share a video I did when my car was diagnosed with rod knock and needed a new engine. Differences with what you have shared are, it was not present at idle and it will increase the rate of sound as the rpms were going up between 1800 and 2800 aprox. then gone up to almost red line were the vibrations were again audible.

hope it helps and foremost GOOD LUCK in finding and solving this.

Sshec152 · 08-06-2016, 09:52 PM

Here are a few more clips of the noise. The first video is the noise while idling. You can hear the noise basically dissapear when i rev the engine.
The second is the noise coming and going while rocking the steering wheel back and forth. I believe i knew what the culprit is put i will check tomorrow and report back.

07-31-2016, 06:30 PM	#1
Sshec152 Private First Class 43 Rep 160 Posts Drives: 2007 335i coupe Join Date: Jun 2015 Location: Delaware county iTrader: (0)	Rod knock? A couple of weeks ago i was sitting in the drive through when i heard a metallic tapping/knocking noise. Its not always constant, it wont do it during a cold start until the rpms drop to a normal idle, i can be sitting idling and all of a sudden it will make the noise and randomly go away. I found that if i drive for a while on the highway then come to a stop it will take a while until it does it, and i also found that if it does it while im sitting still and i turb the wheel slowly it will basically dissapear. The noise will speed up with revs until about 2500rpm then go away. Im not sure if its rod knock, lifters, etc. I also have a lightweight flywheel that generates slight gear chatter but this noise doesn't go away when i push the clutch in. Vehicle has 101K Last edited by Sshec152; 07-31-2016 at 06:35 PM..
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07-31-2016, 06:48 PM	#2
stashtrey Lieutenant Colonel 295 Rep 1,834 Posts Drives: 08 E90 335xi TiAg Join Date: Dec 2012 Location: Sacramento, CA iTrader: (8) Garage List 2008 E90 335xi Sedan [0.00]	That doesn't sound very promising. Wish you the best of luck getting it figured out and it's not what you think it is.
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08-01-2016, 11:11 AM	#3
Jeff@TopGearSolutions 3472 Rep 79,211 Posts Drives: C6 Z06, 09 335i, 10 335xi Join Date: Dec 2008 Location: www.TopGearSolutions.com iTrader: (37)	I'd normally say that motor is toast but if it goes away maybe something is just loose, get under the car and start checking connections on stuff, first.
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08-01-2016, 12:42 PM	#4
maaaaackle Private 12 Rep 82 Posts Drives: 2011 BMW 335is Join Date: Jan 2016 Location: California iTrader: (2)	It sounds like rod knock to me. does the noise get faster as you get on the gas? Just to be absolutely sure I would make sure your nothings loose under there...
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08-01-2016, 05:53 PM	#5
Sshec152 Private First Class 43 Rep 160 Posts Drives: 2007 335i coupe Join Date: Jun 2015 Location: Delaware county iTrader: (0)	The fact that it goes away is the only hope i have right now, im gonna drain/check the oil and see if anything is loose, the sound is more prominent on the driver side but i still have not been able to pinpoint it. Anything over there that could possibly cause that noise? I also recently replaced my serp belt, tensioner and p/s pulley with the ecs one because my oem one was broken. Ive heard of the tensioner making that noise so i will also check that and report back!
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08-01-2016, 11:02 PM	#6
agustincuenca First Lieutenant 154 Rep 343 Posts Drives: 2008 E90 335i; 2016 F80 M3 Join Date: Sep 2014 Location: S Louis iTrader: (0) Garage List 2016 BMW M3 [0.00] 2008 BMW 335i [0.00]	I can share a video I did when my car was diagnosed with rod knock and needed a new engine. Differences with what you have shared are, it was not present at idle and it will increase the rate of sound as the rpms were going up between 1800 and 2800 aprox. then gone up to almost red line were the vibrations were again audible. hope it helps and foremost GOOD LUCK in finding and solving this.
	Appreciate 0 Quote

08-06-2016, 09:52 PM	#7
Sshec152 Private First Class 43 Rep 160 Posts Drives: 2007 335i coupe Join Date: Jun 2015 Location: Delaware county iTrader: (0)	Here are a few more clips of the noise. The first video is the noise while idling. You can hear the noise basically dissapear when i rev the engine. The second is the noise coming and going while rocking the steering wheel back and forth. I believe i knew what the culprit is put i will check tomorrow and report back.
	Appreciate 0 Quote