knocking problem when car sits for 10 to 12 hrs.
Thread Starter
5th Gear
Joined: Oct 2006
Posts: 5
Likes: 0
knocking problem when car sits for 10 to 12 hrs.
05' Z51 17,000 miles makes a small knocking sound in the mourning or when the car sits for a period of time. the sound gose away when the car warms up. was think I should take it to the dealer but they'll say probably ran i without oil. was worndering if their was and suggestions.
Melting Slicks
Joined: Sep 2005
Posts: 2,670
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From: merritt island fl
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Could be piston slap. Or, worse, a rod bearing. Do a search on piston slap. If a rod bearing, it will probably worsen quickly.
Safety Car
Joined: Dec 2006
Posts: 4,642
Likes: 9
From: Dalllas/Ft Worth Area TX
How about replacing the oil filter, maybe the check valve inside is leaking back and draining the upper passages. Also a lifter could be sticking until warmed up, I have used Mystery Oil in the past to loosen lifters. In non vet engines I tried all different types of additives (including trans fluid) but but finally gave up and tried Mystery Oil and it worked. The engine guys at the parts store kept swearing by it and it did work, it took several years before I tried it, maybe the name turned me off. Good luck!
Racer
Joined: Aug 2005
Posts: 449
Likes: 68
05' Z51 17,000 miles makes a small knocking sound in the mourning or when the car sits for a period of time. the sound gose away when the car warms up. was think I should take it to the dealer but they'll say probably ran i without oil. was worndering if their was and suggestions.
Melting Slicks
Joined: Mar 2001
Posts: 3,252
Likes: 61
From: League City TX
05' Z51 17,000 miles makes a small knocking sound in the mourning or when the car sits for a period of time. the sound gose away when the car warms up. was think I should take it to the dealer but they'll say probably ran i without oil. was worndering if their was and suggestions.
Thread Starter
5th Gear
Joined: Oct 2006
Posts: 5
Likes: 0
took my car to the dealer and explained the problem they had the car for 2 days. So I called today to get a update and they said that the knocking sound was normal, especially from an aluminium block... I don't believe them...
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Safety Car
Joined: Dec 2006
Posts: 4,642
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From: Dalllas/Ft Worth Area TX
Have you tried the oil filter change yet? If there is a defective check valve in the filter and the oil drains out of the upper galaxities (oil passagies), it could easily cause noise on start up and wear. I've had this problem before.
Cruising
Joined: Feb 2007
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Have your car serviced. That's the best way to identify the problem correctly.
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Racer
Joined: Jul 2006
Posts: 462
Likes: 8
From: Las Vegas NV
Same with mine, colder weather starts make it more noticeable. Sounds like a diesel, not loud but you hear it for a minute or two. Sounds like piston slap not valve train noise. From what I understand it's a quality control issue with these engines.
jer
jer
Race Director
Joined: Oct 2004
Posts: 10,089
Likes: 13
The filter anti-drainback valve is designed to prevent the filter from emptying of oil when the engine is stopped. But on the LS2, the filter is oriented so the oil can't drain out of the filter when the engine is stopped (unless the car is inverted). So it does nothing useful. In a car where the filter is mounted the other way (opening down), it is important, but not here.
SC CF Senior Member
Joined: Feb 2006
Posts: 1,227
Likes: 0
From: Friendswood Texas
St. Jude Donor '06-'07-'08
Mine was doing the same thing. Brought it into Chevy and they said it was normal and to just let it do what AU N EGL explained. Doesn't do it when I let it warm up. Do I agree with it??...No! Do I have any other choice?...Probably not
Oh well
Drifting
Joined: May 2005
Posts: 1,560
Likes: 334
From: Indianapolis Indiana
The filter anti-drainback valve is designed to prevent the filter from emptying of oil when the engine is stopped. But on the LS2, the filter is oriented so the oil can't drain out of the filter when the engine is stopped (unless the car is inverted). So it does nothing useful. In a car where the filter is mounted the other way (opening down), it is important, but not here.
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Well you do, but not worth it for the average person. I run a 3 qt accu-sump and oil cooler in my car. ( pheudo race car).
When I get in I turn the key ( yes I still have a key) to accesory, not starting the car. Flip the accusup switch, which will circulate oil though to block to pre-lube the block. The oil pressure goes up to 40 psi, after 20 sec or so, I start the engine. No pistion slap.
Some of those old oil advertisments say the hardest thing you can do to your engine is to start it.
Safety Car
Joined: Dec 2006
Posts: 4,642
Likes: 9
From: Dalllas/Ft Worth Area TX
The filter anti-drainback valve is designed to prevent the filter from emptying of oil when the engine is stopped. But on the LS2, the filter is oriented so the oil can't drain out of the filter when the engine is stopped (unless the car is inverted). So it does nothing useful. In a car where the filter is mounted the other way (opening down), it is important, but not here.
Racer
Joined: Jul 2006
Posts: 462
Likes: 8
From: Las Vegas NV
Well you do, but not worth it for the average person. I run a 3 qt accu-sump and oil cooler in my car. ( pheudo race car).
When I get in I turn the key ( yes I still have a key) to accesory, not starting the car. Flip the accusup switch, which will circulate oil though to block to pre-lube the block. The oil pressure goes up to 40 psi, after 20 sec or so, I start the engine. No pistion slap.
Some of those old oil advertisments say the hardest thing you can do to your engine is to start it.
When I get in I turn the key ( yes I still have a key) to accesory, not starting the car. Flip the accusup switch, which will circulate oil though to block to pre-lube the block. The oil pressure goes up to 40 psi, after 20 sec or so, I start the engine. No pistion slap.
Some of those old oil advertisments say the hardest thing you can do to your engine is to start it.
jer