Slight knock... 18k miles?
Thread Starter
On The Tree
Joined: Sep 2006
Posts: 133
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Slight knock... 18k miles? I bought my car 1 week ago today, when i bought it, it had 17.5k miles on it, and was garage for 2 years.
I hear a slight knock in the engine.. after i've driven it for a bit of time it goes away.. and all i can hear is the belt whining a bit (new belt).
Anyways, I put some fuel injector cleaner in, followed by a bottle of seafoamed into the gas. This lessened the knock, but it's still there.
Anyone have any suggestions to what it could be? I guess i need to check the plugs, although i was resenting it the car is practicaly brand new. I'm also going to change the fuel filter to see if that helps anything.
I just need some possible solutions to what could be the problem after garaging a car for 2 years, what needs to be changed after this amount of time.
I checked the MAF, its clean.
I'm throwing 0 codes, and i have 0 decrease in performance on the track and daily driving (13.444 @ 105.80 -stock only air lid + K&N)
Please help
I hear a slight knock in the engine.. after i've driven it for a bit of time it goes away.. and all i can hear is the belt whining a bit (new belt).
Anyways, I put some fuel injector cleaner in, followed by a bottle of seafoamed into the gas. This lessened the knock, but it's still there.
Anyone have any suggestions to what it could be? I guess i need to check the plugs, although i was resenting it the car is practicaly brand new. I'm also going to change the fuel filter to see if that helps anything.
I just need some possible solutions to what could be the problem after garaging a car for 2 years, what needs to be changed after this amount of time.
I checked the MAF, its clean.
I'm throwing 0 codes, and i have 0 decrease in performance on the track and daily driving (13.444 @ 105.80 -stock only air lid + K&N)
Please help
If the car sat for that long, the oil could have run out of the whole motor and it was dry at startup... if that happened, you could have disturbed something. It's always a good idea to start a ar up at least once a month or more to keep the oil moving around in the motor.
Has it gone away, or does it do it all the time? How is the oil pressure? Any smoke? What kind of oil filter are you using? I'd change the oil and see what it looks like, might tell you something.
Has it gone away, or does it do it all the time? How is the oil pressure? Any smoke? What kind of oil filter are you using? I'd change the oil and see what it looks like, might tell you something.
piston slap most likely or the usual valvetrain noise (all normal), i've heard it on about every stock fbody 00 and up. if it is a knock...what octane gas are you using? you can try to use a higher octane also check your plugs.
Thread Starter
On The Tree
Joined: Sep 2006
Posts: 133
Likes: 0
93 octane ONLY. the oil looks clean, but im going to change to synth. soon.
i guess i'll check the plugs... and for the record, no smoke at all. the exhaust smells very clean.
the oil pressure is great.. never had a problem with that, the first statup it had pressure, and brand new oil, although it wasn't synthetic.
it does it all the time, mainly noticable under a heavy load, and very feint at idle, but after a while it stops.. if i run my car for a long period of time, or run it hard like at the track..
I guess everything points to the plugs..
i guess i'll check the plugs... and for the record, no smoke at all. the exhaust smells very clean.
the oil pressure is great.. never had a problem with that, the first statup it had pressure, and brand new oil, although it wasn't synthetic.
it does it all the time, mainly noticable under a heavy load, and very feint at idle, but after a while it stops.. if i run my car for a long period of time, or run it hard like at the track..
I guess everything points to the plugs..
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thank you guys for making my day better 
Yep, if it goes away when the car warms up or gets better, the piston is swelling up inside the bore like it should. Just a little too much tolerance when cold. Very much a norm for these motors. You should here mine 
the same thing is going on with mine.... when you start it the tapping begins...when you put it in gear esp reverse it gets louder... afte ryou drive it for awhile just the normal injecter tick let it sit for a little while it starts right back... mine is on the passenger side back of the motor... you can hear it better in the fender well an right where the vents are in the fender.... sounds like some one taking a hammer an hitting the pavement lightly speeds up with the speed of the motor .... but like i said goes away when you drive it for a bit.... the car has 157k i just wonder if its piston slap or lifter.....
I have 26k miles and mine has a slight piston slap on cold starts pisses me off cause someone noticed it today and said u got the good ole ls1 piston slap ughhhh. I guess the only way to fix it is to have the bottom end rebuild with different pistons.
Odds are that it is piston slap, my car has it too. FYI Northstar V8s have a knocking noise pretty bad too. But it you run a bottle of GM Top Engine Cleaner through them it will loosen the carbon buildup on the pistons and will take care of the noise for a while. Don't think it will help your noise but it's something you can try. Also, GM has a service bulletin on the GEN III motors for a knocking noise that is due to the O-Ring being cut from the pickup tube to the oil pump causing an aeration of the oil leading to a knocking sound. I've never ran across it but thought that I'd let you know.