Random knock?
Thread Starter
6th Gear
Joined: Jul 2017
Posts: 6
Likes: 0
Random knock?
Okay so heres the latest problem with my girls c4 nightmare.
it has a random knock. And i mean random. It starts knocking as soon as it starts but its inconsistent. It doesnt keep pace with the motor, it literally sounds like something is bouncing off the pistons randomly. Pulled the valve covers and adjusted valve lash and checked the lifter arms and springs, fine. Pulled the oil pan and cant see any visible scarring. I found very trace amounts of metal shards in the oil (but still scary). Im at a loss. I have no idea what could be causeing this. And im asking for any help anyone can give me. What else should i look at? Has anyone ever had this issue before?
it has a random knock. And i mean random. It starts knocking as soon as it starts but its inconsistent. It doesnt keep pace with the motor, it literally sounds like something is bouncing off the pistons randomly. Pulled the valve covers and adjusted valve lash and checked the lifter arms and springs, fine. Pulled the oil pan and cant see any visible scarring. I found very trace amounts of metal shards in the oil (but still scary). Im at a loss. I have no idea what could be causeing this. And im asking for any help anyone can give me. What else should i look at? Has anyone ever had this issue before?
Le Mans Master
Joined: Feb 2005
Posts: 6,479
Likes: 565
From: Clearwater Florida
..... Anything loose on the motor ? brackets , mounts , etc . , starter motor ? how about a bad A.I.R. pump ? A/C compressor ? exhaust system pre-cats ? flywheel/flexplate ? Check for anything that might be rattling around on the engine .....
Thread Starter
6th Gear
Joined: Jul 2017
Posts: 6
Likes: 0
Yes it happens at idle, it sounds like its coming from the passenger side underneath the valve cover but i cant see anything out of the ordinary. What was weird is when i went to put it on ramps, i put it in drive (its an auto by the way sorry for not mentioning that) it idled down and the noise stopped. But when i gave it gas to get on the ramps it started again, put it back in park and it was still there.
Drifting
Joined: Mar 2017
Posts: 1,897
Likes: 164
From: Nashville TN
2017 C4 of Year Finalist
Yes it happens at idle, it sounds like its coming from the passenger side underneath the valve cover but i cant see anything out of the ordinary. What was weird is when i went to put it on ramps, i put it in drive (its an auto by the way sorry for not mentioning that) it idled down and the noise stopped. But when i gave it gas to get on the ramps it started again, put it back in park and it was still there.
A video might help people here diagnose the issue with you. Think you could take a 30-second clip?
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
try starting it without the belt
may check for an exh leak at the manifold and the pipe that comes off it going to the intake. Somtiems when cold youll hear it clack then quiets up some as it gets warmer
may check for an exh leak at the manifold and the pipe that comes off it going to the intake. Somtiems when cold youll hear it clack then quiets up some as it gets warmer
Melting Slicks
Joined: Jan 2008
Posts: 2,054
Likes: 120
From: AZ
Belts can mimic all sorts of sounds. Candle wax or different sprays on it can quickly eliminate that possibility.
Why would hydraulic valves need adjusting?
Oil pressure good? Change it recently? Try, perhaps a higher vicsosity.
With no info in your profile and no mileage you'll not get the best feedback!
Why would hydraulic valves need adjusting?
Oil pressure good? Change it recently? Try, perhaps a higher vicsosity.
With no info in your profile and no mileage you'll not get the best feedback!
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