help with ls1 valvetrain noise

uglyman · 08-23-2007, 03:56 PM

'98 trans am 148k miles. literally sounds like a bird chirping at idle coming from around center of engine, you can listen to both sides and hard to distinguish exactly where it originates. i removed the rockers and found 3 bent pushrods. replaced the whole set and knew i had fixed the problem but didn't happen. still got the bird under the intake. any way the lifters or anything else could have been damaged from the bent pushrods? just hate to pull the intake and not know some direction of what to look for. guess i bought more "bird" than i bargained for huh? thanks for any help!

**Raven02ta** · 08-24-2007, 05:37 AM

Originally Posted by uglyman

'98 trans am 148k miles. literally sounds like a bird chirping at idle coming from around center of engine, you can listen to both sides and hard to distinguish exactly where it originates. i removed the rockers and found 3 bent pushrods. replaced the whole set and knew i had fixed the problem but didn't happen. still got the bird under the intake. any way the lifters or anything else could have been damaged from the bent pushrods? just hate to pull the intake and not know some direction of what to look for. guess i bought more "bird" than i bargained for huh? thanks for any help!

Actually your lifters are under your heads, so pulling the intake will not tell you anything about your lifters.

Have you pulled the belt off to make sure it isnt just a bad pulley?

uglyman · 08-24-2007, 07:36 AM

i think it's going to be a lifter. hopefully hasn't damaged the cam yet. yeah i tried the belts and they did actually contribute to a lot of the noise but still got the same noise i was trying to eliminate. thanks for the input, i'm not really up to date on these engines and didn't realize you must pull the heads to get the lifters out.

**Raven02ta** · 08-24-2007, 09:09 AM

Originally Posted by uglyman

i think it's going to be a lifter. hopefully hasn't damaged the cam yet. yeah i tried the belts and they did actually contribute to a lot of the noise but still got the same noise i was trying to eliminate. thanks for the input, i'm not really up to date on these engines and didn't realize you must pull the heads to get the lifters out.

the best thing you could get to help you out with the tear down would be this book. you can get it at almost any book store.

http://search.barnesandnoble.com/boo...84089848&itm=2

**thecorrectformula** · 08-24-2007, 09:30 AM

I just ordered that book. It's supposed to be here in a couple days

**Raven02ta** · 08-24-2007, 11:38 AM

its a great book for general knowledge and most torque specs, i also keep the haynes manual handy for a couple things that may not be in the book. but other wise has great build information. i have used it lots of times on several different builds. however now most of the knowledge is all in the brain.... but sometimes that farts and i need to go look in a book :P

**thecorrectformula** · 08-24-2007, 12:01 PM

I'm planning on using it mainly for the torque specs and for those procedures I've never done before.

**98formy** · 08-28-2007, 08:56 AM

I had the same squeak. It turned out to be a bad tensioner. Have you tried taking the main belt off and running it for a short time to determine if it is in fact the belt and not the lifters?

**Raven02ta** · 08-28-2007, 08:58 AM

Originally Posted by 98formy

I had the same squeak. It turned out to be a bad tensioner. Have you tried taking the main belt off and running it for a short time to determine if it is in fact the belt and not the lifters?

see below

Originally Posted by uglyman

i think it's going to be a lifter. hopefully hasn't damaged the cam yet. yeah i tried the belts and they did actually contribute to a lot of the noise but still got the same noise i was trying to eliminate. thanks for the input, i'm not really up to date on these engines and didn't realize you must pull the heads to get the lifters out.

**Street Lethal** · 08-28-2007, 10:44 AM

Originally Posted by uglyman

i think it's going to be a lifter....

The bird chirping noise is definitely not a collapsed, or a potentially collapsed lifter (although at that mileage, it wouldn't hurt to swap them out anyways). If the noise is constant, and came with the car, I'd pull the throttle body off and inspect any possible gasket obstruction in conjunction with the intake's "mouth port", causing some minor turbulence. If the noise is not constant, as already mentioned, I'd look into the tensioner, A/C clutch, power steering pulley, etc (not just the belt itself)....

**thecorrectformula** · 08-29-2007, 06:22 AM

Hey do you have to pull the manifold to get the lifters out or is it just the heads

**Raven02ta** · 08-29-2007, 07:31 PM

Originally Posted by thecorrectformula

Hey do you have to pull the manifold to get the lifters out or is it just the heads

intake manifold is connected to the heads.... its how air is sent into the cyl through the intake valve inside the head.... so yes they are connected

**thecorrectformula** · 08-29-2007, 07:39 PM

Okay my bad I wasn't thinking. I was buzzing pretty bad when I first read this thread.

**Raven02ta** · 08-30-2007, 05:34 AM

Originally Posted by thecorrectformula

Okay my bad I wasn't thinking. I was buzzing pretty bad when I first read this thread.

its all good

uglyman · 08-30-2007, 11:33 AM

thanks for the replies, it's not a belt or tensioner b/c i tried that first. however the noise goes away when you just take the engine off idle (probably around 12-1600 rpm) then turns into what sounds like a loose rocker arm above 1600 rpm. when it idles back down the noise comes right back. i'm pulling the heads and i'll let you guys know what i find thanks again!!