vaughnZ02

Hey guys. I am new to the forum but not new to F-bodies. I have had a ’69 bird and currently have a ‘94 z-28, ‘02 z-28 (both daily driven) and a ’72 camaro (project with my Dad). I am new, as of a few months ago to LS1 cars though.

With the ’02, I am experiencing a hammering noise that begins as soon as I fire the engine and persists for exactly 1:45 to 1:50 every time. It is consistent in appearance and duration when the car is cold started but doesn't really occur when the car is warm started. The noise increases with RPM as you will see in the video. In this video, the sound goes until 1:49 and then turns completely off with a clunking noise followed by a pewwm sound. The sound can also only be heard from inside the car and sounds loudest as you move towards the area of the brake booster. Since the noise can’t really be heard outside the cabin, it has been difficult to find under the hood.

I have searched the forums for a similar issue and all I have really found is references to piston slap and accessory component failures. I am sure that the sound is not piston slap and I have ruled out power steering pump, alternator and water pump.

Please take a look at the video. Most important part is from 1:30 to 1:55
Any input would be very helpful.

vaughnZ02

Just realized I posted this in the suspension area. Could a moderator please move this to the New LS1 owners area? Thank you.

venom99

iTrader: (32)

sounds like its in your valve terain

O2Form

Might be the AIR valves.

BOA279

iTrader: (1)

I bet its your air pump going out. On the drivers side, under the two fuse boxes you will find the air pump. Either unplug it or pull the fuse for it and I bet the noise is gone (you will however throw a code during this test). On warm start it probably wont turn on because the cat's are already working....there is no need for it to turn on....let me know if thats it.

(Your new to F-bodys so: The "AIR system" is basically a pump that pushes normal air into the exhaust on start up. The air (oxygen) and the exhaust (fuel) combust at the cats and makes them get hot faster to reduce emissions quicker. The pump only runs on cold startup when the cat's are cold.)

camaro981289

iTrader: (25)

LS1's are known for their loud noisy valve trains and alot of it is normal. Yours sounds excessively loud though. I would try unplugging the air pump to see if its that by removing the air pump fuse.

O2Form

oil pressure is kinda low too

rumblebox

iTrader: (9)

im kinda curious at this point too lol

NBM-LS1

iTrader: (7)

Man thats an odd issue you have. Def pull the fuse on the circuit for the AIR pump. I just find it hard to believe that its the AIR pump since the noise increases with engine rpm. But I have yet to run across this described problem in the automotive field.

Anthony Williams

iTrader: (3)

Well it sounds alot like my old engine that had 2 flatted lifter rollers and low/fluctuating oil pressure.

BRUTL

iTrader: (27)

Well, my air pump is giving up on life, as it whines up a storm while its running. Funny thing is, I know its not belt driven, but damn if the pitch of that whine doesnt change when I rev the engine up. Unplug the damn thing while its running and then she's all quiet. So have you tried this yet? The "Pewwm" noise sounds like how I would describe the way it sounds when the air pump turns off and winds down.