Engine knock when cold
Thread Starter
Instructor
Joined: Apr 2005
Posts: 184
Likes: 0
From: Oak Ridge New Jersey
Engine knock when cold
Lately I have been hearing a knock in the engine when it is cold. This only happens after the car has sat overnight. The knock goes away after 2-3 min. My car is an 05 with just over 17,000 miles. The oil has been changed 4 times at 3500-4000 mile intervals. Anyone else having this problem please respond. Rick.
Melting Slicks
Joined: Jun 2004
Posts: 3,439
Likes: 6
From: Newark, DE
St. Jude Donor '06
On a low mileage, well maintained vehicle like yours, I doubt that it is actually engine knock that you are hearing. The stock oil filter has great filtration properties, but has very poor flow characteristics. I think what you are hearing is "normal" cold start valvetrain noise, caused by the low flow. It goes away after the engine oil warms up.
At your next oil change, instead of the stock Delco, try a Baldwin B31 or a K&N HP-1007 filter instead. Unless you are actually unlucky enough to have real knock, I'll bet the noise will be gone.
At your next oil change, instead of the stock Delco, try a Baldwin B31 or a K&N HP-1007 filter instead. Unless you are actually unlucky enough to have real knock, I'll bet the noise will be gone.
Melting Slicks
Joined: Nov 2004
Posts: 3,064
Likes: 6
From: Pinellas Park Florida
The service manual says you may need an oil filter with anti-drain back, so I would have to agree with Mr. Lucky
I dunno about which filter has that ability; I use Mobile 1 filters (M107) and no start up noise. When I use AC Delco, I get the lifter/rocker noise
I dunno about which filter has that ability; I use Mobile 1 filters (M107) and no start up noise. When I use AC Delco, I get the lifter/rocker noise
Last edited by AutoCutter; Oct 9, 2006 at 07:18 AM.
Thread Starter
Instructor
Joined: Apr 2005
Posts: 184
Likes: 0
From: Oak Ridge New Jersey
Thanks for the replies. I am going to try a different oil filter and put a magnetic drain plug in and see if there is any metal in the oil. I hope that is just low oil flow when cold. Thanks again. Rick (save the wave)
Pro
Joined: Sep 2006
Posts: 516
Likes: 0
From: Boone Lake Tennessee
Originally Posted by Whiteonrice
Piston slap?? Have to leave it at the dealer overnight for a diagnosis. Big problem with the LS1s. 
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Originally Posted by srpbaer
I agree 10000%...Piston slap...a long time trademarke of the Corvette...Don't waste any time trying to get this fixed...does no damage and will always be there!!!
Burning Brakes
Joined: Aug 2004
Posts: 1,196
Likes: 4
From: Latham NY
Originally Posted by Mr. Lucky
On a low mileage, well maintained vehicle like yours, I doubt that it is actually engine knock that you are hearing. The stock oil filter has great filtration properties, but has very poor flow characteristics. I think what you are hearing is "normal" cold start valvetrain noise, caused by the low flow. It goes away after the engine oil warms up.
At your next oil change, instead of the stock Delco, try a Baldwin B31 or a K&N HP-1007 filter instead. Unless you are actually unlucky enough to have real knock, I'll bet the noise will be gone.
At your next oil change, instead of the stock Delco, try a Baldwin B31 or a K&N HP-1007 filter instead. Unless you are actually unlucky enough to have real knock, I'll bet the noise will be gone.
yes its true try and see
