Help!! Tapping noise when engine is warm.
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From: Chandler, AZ
Help!! Tapping noise when engine is warm. My car has been making a tapping noise for a while. It doesn't make it on start up when cold, but after a 5-10 minutes of city or freeway driving i starts making a tapping sound that sort of sounds like a major exhaust leak. The frequency of the tapping increases with RPM and gradually gets louder the longer i drive. If I park the car and let it cool down for 30-60 minutes is goes away or at least gets quieter. If it is making the noise and I go WOT thru 1st and 2nd, the noise will go away for about 10-15 minutes, then come back. I know I either have a worn oil pump or just a bad oil pressure sensor as my gauge reads ~10-15 psi on cold start and will jump around alot at idle. It will read up to ~40 psi at upper RPMs. Today while on the freeway I heard what sounded like a knock while crusing at about 2200 RPM while it was making the same tapping noise.
My guess is a bad/worn lifter, rocker, spring, or maybe even a bent pushrod. But wouldn't it make the noise at all RPM and temps if is was those though?
O, and FYI 99' Z28 M6 134K miles w/ Pacesetter LT's and ORY
My guess is a bad/worn lifter, rocker, spring, or maybe even a bent pushrod. But wouldn't it make the noise at all RPM and temps if is was those though?
O, and FYI 99' Z28 M6 134K miles w/ Pacesetter LT's and ORY
Diagnosing a tap or knock in a ls1 can be tough. Could be so many different things. !st thing i would do in your case is to replace the oil sending unit and make sure you have proper oil pressure. Knocking hot could so many different things. It sounds to me like it could be a carbon related knock or piston noise. If you could post up a audio or video clip that would help.
A rod bearing knock would be louder when the engine is hot and as you rev it it would knock louder. Also you would notice the oil would look a little silvery when you change it.
Lifter noise could be anything from a light ticking to a constant loud tapping that doesn't really change much when you rev it.
Built up carbon can also make a ls1 sound knocky, like a diesel.
My 02 ticks and taps 30 seconds after you start it cold then sounds like a clattering old 6 cylinder until it gets hot then its quiet but sometimes has a knock-tap noise that comes and goes.
Oil looks clean and not silvery and it has 60 psi oil pressure cold idle 45psi hot idle.
I've also heard some ls1 engines that were quiet but never silent like the older gm engines. The ls1 engines tend to be noisy.
Could be a exhaust leak too.
Good Luck.
A rod bearing knock would be louder when the engine is hot and as you rev it it would knock louder. Also you would notice the oil would look a little silvery when you change it.
Lifter noise could be anything from a light ticking to a constant loud tapping that doesn't really change much when you rev it.
Built up carbon can also make a ls1 sound knocky, like a diesel.
My 02 ticks and taps 30 seconds after you start it cold then sounds like a clattering old 6 cylinder until it gets hot then its quiet but sometimes has a knock-tap noise that comes and goes.
Oil looks clean and not silvery and it has 60 psi oil pressure cold idle 45psi hot idle.
I've also heard some ls1 engines that were quiet but never silent like the older gm engines. The ls1 engines tend to be noisy.
Could be a exhaust leak too.
Good Luck.
Last edited by 99RTA; Sep 12, 2009 at 11:17 AM.
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Noisy tap My car has been making a tapping noise for a while. It doesn't make it on start up when cold, but after a 5-10 minutes of city or freeway driving i starts making a tapping sound that sort of sounds like a major exhaust leak. The frequency of the tapping increases with RPM and gradually gets louder the longer i drive. If I park the car and let it cool down for 30-60 minutes is goes away or at least gets quieter. If it is making the noise and I go WOT thru 1st and 2nd, the noise will go away for about 10-15 minutes, then come back. I know I either have a worn oil pump or just a bad oil pressure sensor as my gauge reads ~10-15 psi on cold start and will jump around alot at idle. It will read up to ~40 psi at upper RPMs. Today while on the freeway I heard what sounded like a knock while crusing at about 2200 RPM while it was making the same tapping noise.
My guess is a bad/worn lifter, rocker, spring, or maybe even a bent pushrod. But wouldn't it make the noise at all RPM and temps if is was those though?
O, and FYI 99' Z28 M6 134K miles w/ Pacesetter LT's and ORY
My guess is a bad/worn lifter, rocker, spring, or maybe even a bent pushrod. But wouldn't it make the noise at all RPM and temps if is was those though?
O, and FYI 99' Z28 M6 134K miles w/ Pacesetter LT's and ORY
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Gee, thanx! I've searched all threads Thanks for telling me to go read but I'm a voracious reader and I don't need anybody to tell me to do that I do that first especially in these blog pages cuz that's where you get the best info not this time
Last edited by Zach Firoved; Apr 30, 2021 at 12:26 PM. Reason: Forgot something.
start a new thread! 
