What is this knocking noise...lifter?

[GNICTRY]

no when i got it it had the wrong throttle body so it wouldnt shift past 4500rpm...i havent hit the rev limiter but once since i have had it but the people b4 me werent the best at taking care of it

[matt100psi]

Hey, thanks for posting this, mine has what sounds like exactly the same noise with no codes thrown. Not feeling so good after reading the reply by 98ws6zo6.

Anyway, I guess I'll try pulling the valve covers and looking at the rods as recommended.

Incidentally, I took it to a local LS1 shop and they suggested pulling the belts to make sure it wasn't an accessory. I did, and it wasn't. I think it sounded a bit louder down by the crankshaft than up top, but it's hard to say.

The good news is that this extra knocking drowns out the squeak of the idler pulley.

Matt

[GNICTRY]

i no what u mean i have been able to take the valve covers off to look...i just got the trans in to make it drivable...it not as bad once oil get going...i pretty sure its the lifter/push rods...we'll see

[matt100psi]

Are you guys serious about this taking 30 minutes? Granted I'm not a top mechanic, but I've been working for like 1.5 hours just to get the driver side coil pack assembly off, and the passenger side seems like it's going to be worse. Something I'm missing? The bolt closest to the firewall is covered by some clip attached to something else I have to figure out how to remove in order to get the bolt off.

[Frost]

Are you guys serious about this taking 30 minutes? Granted I'm not a top mechanic, but I've been working for like 1.5 hours just to get the driver side coil pack assembly off, and the passenger side seems like it's going to be worse. Something I'm missing? The bolt closest to the firewall is covered by some clip attached to something else I have to figure out how to remove in order to get the bolt off.

an hour and a half to take off a coil pack??

[matt100psi]

Ahh...I see. I stupidly thought the assembly (the metal piece all the packs attach to) had to come off, and the bolt in the very back is a real jerk. Yes, it's much easier just taking off the individual packs, and I see the 8mm bolts are accessible beneath them.

How bent would a bent rod be to cause knocking? Is it something I'd clearly see?

Thanks,
Matt

[LETHALxLS1]

Roll it on a flat surface and it should be pretty obvious if its bent. You should keep track of which goes where and put each back where it came from.

[FORMULA7]

I have the same noise problem.I will admit that I hit the limiter several times(sighs).I took of my valve covers and rockers,push rods.Rolled the push rods on a glass surface and all came rolling flat.This was like 3 or 4 years ago.Ive been driving it ever since.I wouldn't recommend it,but the noise kind of goes away after the motor warms up.

I think its either a vent valve or a bad lifter.

[matt100psi]

Thanks for the feedback and advice, guys. I looked at the rods/rockers for the odd cylinders and they all looked fine. Not really wanting to go through the process on the even cylinders if I didn't have to, I got a stethoscope to hear what I could hear. It was the driver's side (the side I checked) that was worse, and worse near the valves than near the rockers. So lifters or valves seem like reasonable hypotheses. What's a "vent valve"?

If the sound went away after the engine was warm, I'd think it was a matter of some component heating up to its spec'd size. But for me, I hear the sound at idle regardless of engine temperature. I think I just don't hear it much at higher RPMs because of other engine noise.

Matt

[LETHALxLS1]

Thanks for the feedback and advice, guys. I looked at the rods/rockers for the odd cylinders and they all looked fine. Not really wanting to go through the process on the even cylinders if I didn't have to, I got a stethoscope to hear what I could hear. It was the driver's side (the side I checked) that was worse, and worse near the valves than near the rockers. So lifters or valves seem like reasonable hypotheses. What's a "vent valve"?

If the sound went away after the engine was warm, I'd think it was a matter of some component heating up to its spec'd size. But for me, I hear the sound at idle regardless of engine temperature. I think I just don't hear it much at higher RPMs because of other engine noise.

Matt

Why didnt you check them all?

[matt100psi]

Because despite claims that all 8 can be done in 15-30 minutes, it took me significantly longer for just the 4 I did, and the stethoscope indicated that the problem was on the driver's side.

Matt

[LETHALxLS1]

I would check them all-I wouldnt care if it took 2 days.

[LETHALxLS1]

I have the same noise problem.I will admit that I hit the limiter several times(sighs).I took of my valve covers and rockers,push rods.Rolled the push rods on a glass surface and all came rolling flat.This was like 3 or 4 years ago.Ive been driving it ever since.I wouldn't recommend it,but the noise kind of goes away after the motor warms up.

I think its either a vent valve or a bad lifter.

If the noise you hear goes away when the engine warms up then I would say its piston slap. My car has it too.

[matt100psi]

I would check them all-I wouldnt care if it took 2 days.

I see. This is the first time I've used a stethoscope for diagnosis. In your experience, are they not generally precise enough to distinguish a noise on one side of the engine vs. the other side?

Thanks,
Matt

[LETHALxLS1]

I see. This is the first time I've used a stethoscope for diagnosis. In your experience, are they not generally precise enough to distinguish a noise on one side of the engine vs. the other side?

Thanks,
Matt

Dude-check the other side. If you dont find anything take the car to someone who knows F bodies so they can listen to it. If you can hear the noise after the engine gets hot then something is wrong.

[98ws6zo6]

hey im not saying im just sayin, i'll put my bottom dollar you pull those heads and at least one or two lifters aren't gonna slide out of the bore like they should.........

[c5z28]

hey im not saying im just sayin, i'll put my bottom dollar you pull those heads and at least one or two lifters aren't gonna slide out of the bore like they should.........

Have you had this problem because I have the same damn thing.

[LETHALxLS1]

reminds me of that song tick tick BOOM!

[knappbunch]

mine makes that sound at cold start but once it warms up it goes away

piston slap? is what everyone seems to say. for mine anyway.

[LETHALxLS1]

pimp slap is way worse than piston slap IMO.