blown87notch

I just got a 96 z28 for my wife and it has a weird chirping noise in the drivers side. It is a sorta screech or a chirp that goes away if it is revved up.

I took it up to the shop and pulled the valve cover and got the stethoscope out and it is defiantly coming from the 5th rocker back. I could here it the best on the stud but I think it would be harmonic up from the lifter, through the pushrod and over to the valve. I then pulled the rocker off and the top of the valve showed a bit of wear but nothing really bad. The cup part of the rocker and the ball seemed fine. I then had my friend start the car while I held the pushrod against the lifter so it wouldn't slap around. The sound was completely gone. After that I switched the rocker with another one to see if the sound would move with the rocker arm. It didn't. Lastly I just adjusted the lash (had a couple ticking) but when that particular rocker was loose the sound was very intermittent. Then I changed the oil.

So I think I have it narrowed down the lifter it's self or the valve. I have never heard a valve make a noise in the guide so I'm hoping it is the lifter.

I do not know much about lt1's but I was told they have hydraulic roller lifters? Is this common for them to go out? I have been doing some searching tonight and read about a few bent push rods that had the same issues, but most of them had roller rockers and guide plates. This car is bone stock.

As far as my first post, I just got this car today for my wife. I couldn't think of any other car that had the same stock power that was easily affordable. I picked this car up (96 z28 auto) for 2k. The only thing wrong with this car was the noise and a bit of paint and a ding in the front. I really want my wife to race this next season with me so help me getting it going.

I attached a picture of the car if your interested.

blown87notch

thanx for the help guys

FANTA-Z

iTrader: (16)

Did you take the pushrod off and look at it while you had the rocker off? Yes they are a hydraulic roller lifter, and they have been known to go out but usually they just dont pump up and make ticking noises not bird chirping sounds.

blown87notch

it sounds just like this http://s145.photobucket.com/albums/r...t=MVI_1112.flv and his thread is here... https://ls1tech.com/forums/lt1-lt4-modifications/627388-interesting-chirping-sound-looking-insight.html and yes I checked the push rod and it seemed fine and not bent.

foggedz

iTrader: (1)

Are you getting oil flow up through that push rod?

blown87notch

yes just as much as the rest of them

Ls1Bait

try running some Rislone lifter and valvetrain cleaner thru your oil. You can get it at any auto parts store. I had a lifter ticking put this stuff in and it stopped. This was about 3 years ago when my motor was stock.

blown87notch

will do I already put some sea fome in it and changed the oil...it is getting quieter

WhyHelloOfficer

iTrader: (5)

Check your pushrods. Pull out the one in question most definitely and roll it on a flat surface. Make sure it rolls evenly. It not its a good chance the pushrod could be slightly bent.

My problem was the actual rocker itself. The nitrous backfire combined with the rocker not being adjusted properly ended up causing this:


It could be a collapsed lifter, which is what I thought it was originally. Best way to tell is to turn the motor over by hand with a breaker bar and a 5/8" socket on the crank pulley. Watch all of the pushrods/rockers and make sure they're all moving the full distance.

If you do lean towards it being a lifter. I'll point you in the right direction for doing the fix. Took me less than 4 hours of actual labor, but you have to let it set for close to 24 to let the RTV seal on the intake.

onephatZ28

iTrader: (8)

My car did that same thing it took me week to find the problem. My problem was a bad rocker. My K&n came off and I got sand in rocker #8 the I had to change all the rocker on my car to be safe.

blown87notch

Yeah man I read your thread when I was searching. I went the other night and pulled the pushrod and it was fine. I switched the pushrod and the rocker with another and the sound is still there in the same place.

From the little extra wear on the top pf the valve I "think" it collapsed or gummed up and then was ran with it being loose, because it was the same rocker I had to tighten to get rid of the tick it had. What do you think?

I have a couple new lifters for it and the intake gasket set to do it. It has just gotten a lot quieter so I have not taken it all off yet.

onephatZ28

iTrader: (8)

I would put the new lifters on and go from there. If that don't work then do the rockers it is one or the other.

WhyHelloOfficer

iTrader: (5)

It probably wouldn't hurt to do a compression test just to make sure the noise isn't coming from a burnt/broken valve. If the car is mostly stock, I'm going to lean more towards it being a collapsed lifter. Another thing you might want to check is the exhaust manifolds for a leak, or a possible blown out gasket. I know some people have had chirping from those as well.

http://www.projecttransam.com/projects2.asp

That's the writeup I used for basically removing the intake manifold and fuel rail. From there its the three bolts on the guideplate retainer and then remove the guideplates. Let the new lifters sit in some oil for a little while so they'll have some oil in them when you install them. I used comp cam assembly lube on the rollers (probably unnecessary) just to be careful when I put everything back together.

The copper rtv is the best to use on the front and rear on the block when re-installing the manifold.

For the lifters I got the GMPP Set from Summit.
The Summit Part# is NAL-12371042

The Felpro intake gaskets from Summit are Part# FPP-1284