Low RPM Valvetrain Clatter

**MarcZ** · 10-14-2012, 04:46 PM

From between 1100 rpms and 2000 rpms I can hear this clanking sound when cold and warm/operating temp, sound like rockers but I'm unable to determine which side it's coming from. It seems like it goes away above 2k, but I'm not sure if I just can't hear it over exhaust. I just bought this car in northern california and drove it down to San Diego, where it began running too hot the longer I drove it and I decided to have it towed home. Even though it never went in the red, I'm hoping the heat didn't damage anything. Turned out to be a bad waterpump which was fixed under aftermarket warranty at a GM dealer. I also had them change the oil and when I picked it up I noticed the noise at low rpms that very same night.

I don't drive the car hard and there was no high rpm event that I can point to as the cause. oil pressure is good everywhere warm and cold.

Here are some videos:

On the first one you can hear it really good 49 seconds into it.

Does this sound bad to you guys?

**MarcZ** · 10-20-2012, 05:21 PM

Pretty surprised I get no replies when I actually have 2 videos, where most people have none with over a page of replies. Anyways.... I took it to a pretty good shop I think I can trust, both techs have 30 years experience and they don't think it's abnormal. He actually says it's warm piston noise. It makes me feel a little better but sometimes the noise freaks me out. I guess I can always get a 2nd opinion but it'll be hard to tell if they just wanna tear the engine down to make some money, this place could have done it easy as it has a short warranty, but they didn't.

**az gt eater** · 10-21-2012, 01:23 AM

Sounds fine to me. Sounds like a really minor case of piston slap. Really minor. Was that a cold start on the first vid? Cause that is less slap than mine does on a warm start.

**az gt eater** · 10-21-2012, 01:26 AM

And the reason why people are prb not posting is because you have a 94 listed, a Z28 as your avatar, you have grey metallic as your car color, yet you show a pewter TA in the vid.

**MarcZ** · 10-23-2012, 07:04 PM

Thanks for the reply, avatar updated. The second video was warm and the sound doesn't go away, it's nearly always there, but only on light throttle above 1,100 rpms, even at 200* operating temps. I can sometimes hear it at idle when I first start the car for about 5 seconds.

**35th-ANV-SS** · 10-23-2012, 07:28 PM

Just for kicks, have you checked for a bent pushrod? Easy to check and would eliminate the noise coming from that.

**2002ssslp** · 10-23-2012, 07:41 PM

It just sounds like normal piston slap to me.

**redbird555** · 10-24-2012, 04:29 AM

Originally Posted by 2002ssslp

It just sounds like normal piston slap to me.

thats piston slap sometimes it goes away when hot sometimes it doesnt I've experimented with a lot of different oils and it seems synthetics make it loud. I just run a good dino 10w40 oil and it helps it some however its still there faintly... just go on about your life lol

**cobra12345** · 10-24-2012, 01:18 PM

mine sounds like that

**MarcZ** · 10-25-2012, 03:50 PM

Thanks for the replies. I'm hearing a lot of people saying theirs sounds like that, puts me at ease.

**2002ssslp** · 10-25-2012, 05:35 PM

LS1 engines were all built loose. It allows the piston to rock in the cylinder, they may make a little noise but they rev faster which is a benefit and it will not hurt reliability.

**04yellowjacket** · 11-05-2012, 04:09 AM

the ls1 in my 04 gto has ticked sinced it has had about 40,000 ,on it. and it now has nearly 110,000 mile on it. still has the same ole tick, the 5.3 in my 99 chevy truck ticked so bad i had to quit running synthetic it. I run 10-40 rotella truck oil in it and all is good now. I run royal purple 20-50 race oil in my gtom and it is alot better than it was, i just hate the price.

**RockinWS6** · 04-22-2013, 07:11 PM

My ws6 has the exact same noise, what you are hearing is air in the lifters. Replace the oring on the pickup tube at the oil pump and it will be quiet again.

Piston slap-noises sound nothing like what you are hearing.

I'll tell you what works to quiet it down is add a few ozs of STP oil treatment. It will fill the air leak at the oring and quiet it down, Unfortunately its just a patch.

I chased my tail on this noise for a few months and had all kinds of different diagnoses from piston slap to rod bearings.

Try this, start the car cold and watch the oil pressure gauge, does it pause at the bottom a little then after a second or two rise up? Start the engine cold and run it for 5 mins then shut it off and look at the oil on the dip stick, does it have tiny little air bubbles in the oil?

**0rion** · 04-23-2013, 10:19 AM

Originally Posted by RockinWS6

My ws6 has the exact same noise, what you are hearing is air in the lifters. Replace the oring on the pickup tube at the oil pump and it will be quiet again.

Piston slap-noises sound nothing like what you are hearing.

I'll tell you what works to quiet it down is add a few ozs of STP oil treatment. It will fill the air leak at the oring and quiet it down, Unfortunately its just a patch.

I chased my tail on this noise for a few months and had all kinds of different diagnoses from piston slap to rod bearings.

Try this, start the car cold and watch the oil pressure gauge, does it pause at the bottom a little then after a second or two rise up? Start the engine cold and run it for 5 mins then shut it off and look at the oil on the dip stick, does it have tiny little air bubbles in the oil?

this thread is a year and a half old....hopefully he has it fixed by now

I agree though......that's not piston slap. I was thinking a bent pushrod or collapsed lifter but what you're describing is also possible.

**RockinWS6** · 04-23-2013, 06:05 PM

Originally Posted by 0rion

this thread is a year and a half old....hopefully he has it fixed by now

I agree though......that's not piston slap. I was thinking a bent pushrod or collapsed lifter but what you're describing is also possible.

LOL do you know what year it is? He posted this a few months ago in oct 2012. I'm trying to help him because that noise is so far from piston slap noise its INSANE.

EVERYTIME A LS1 makes a noise everyone blames it on piston slap. The dealers love it cause it gets um off the hook from fixing these crappy lifters! The stock lifters are ok if you drive like a granny, But if you drive your LS1 hard very quickly the stock lifters start to complain. Partly because they don't get enough oil. I'll betcha if the op replaces the oring and ports his oil pump pr installs a high volume oil pump his engine will be QUIET. I never lie......

**0rion** · 04-23-2013, 07:52 PM

Originally Posted by RockinWS6

LOL do you know what year it is? He posted this a few months ago in oct 2012. I'm trying to help him because that noise is so far from piston slap noise its INSANE.

EVERYTIME A LS1 makes a noise everyone blames it on piston slap. The dealers love it cause it gets um off the hook from fixing these crappy lifters! The stock lifters are ok if you drive like a granny, But if you drive your LS1 hard very quickly the stock lifters start to complain. Partly because they don't get enough oil. I'll betcha if the op replaces the oring and ports his oil pump pr installs a high volume oil pump his engine will be QUIET. I never lie......

my bad......it's only 6 months old.

Piston slap is common and it does cause a lot of people to worry when they first hear it because it sounds like shit. I wouldn't just tear it apart for an o-ring and pump replacement though without getting an accurate oil pressure reading. The stock gauges on the 99+ cars are a joke.

**RockinWS6** · 04-24-2013, 05:56 AM

The air in the oil doesn't effect pressure unless the oring fails completely. The small amount of air getting past the oring ends up in the lifters, mostly towards the frt of the engine. Then the engine sounds like above. I've had some limited success using high mileage oil and a few ozs of STP stop the air leak.