piston slap *WTF*
Staging Lane
Joined: Oct 2006
Posts: 83
Likes: 0
From: Iowa
To me, piston slap sounds more like a light knock than a ticking. If it goes away (or at least gets a lot better) as the engine warms up (about 10 minutes), then it's most likely piston slap. If it sounds the same warm or cold, then you've probably got an exhaust leak or a sticking lifter.
How does an exhaust leak make a perfect ticking sound? Do you mean something is loose on the exhaust and it's the hardware I hear shaking against something causing the ticking? Or do you mean the air pressure involved with exhaust flow is somehow making the perfect ticking sound? It doesn't make sense to me.
Also, it sounds like it's coming from the passenger side of the vehicle, from the engine bay. I don't have a mechanics stethoscope yet, but I've put screwdrivers and things down and can't hear where it's coming from. Perhaps it IS coming from the exhaust manifolds where it connects on the passenger side.
I'm willing to go with piston slap though, since it's been doing it a year, ran on the dyno fairly strong in stock form, and I've never had any problems at all. Although, could the piston slap only be happening on one bank of cylinders like on the passenger side?
Its normal, mine did it, used RP in it and it stopped.
Mine sounds like an old diesel when it is 1st start it cold. To minimize possible damage I let it idle for a few minutes before I drive it. It's also better for after market valve springs. Wouldn't want to risk breaking a cold valve spring. When the motor is at normal running temps it used to sound like a sewing machine before the cam.
Yeah mine does the exact same thing on cold start ups. I don't notice it at all in the summertime. Does anyone have a built bottom end and if so do you still experience piston slap?
Staging Lane
Joined: Oct 2006
Posts: 83
Likes: 0
From: Iowa
I may not be an expert yet, but I do know enough to know that much.
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
Mine does it cold but it goes away in a couple of minutes. But I just bought another car and it's pretty noisy cold and it doesn't completely go away. It varies car to car, but no one has substantiated any problems resulting from it.
I agree - the sound is very diesel-like.
I agree - the sound is very diesel-like.
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Could be an exhaust leak but prolly would have gotten worse if you drive much. Yes piston slap can be on only one bank of engine. Whatever side the cylinder has the loose tolerances is on. Here is the "like a knock" website but don't let it scare you, It's BULL$h!t!!! www.pistonslap.com
RP = Royal Purple (I have tried several oils and no difference)
Try SEAFOAM if it really bugs you. THEN run Top Tier fuel + a bottle of Techron every now and then to help keep carbon down so it won't come back.
Lots of great info on this in the Chevy Talk Website. Search CSK or Cold Start Knock in the 99 up truck section. You will learn all you want to know. My advice is to drive it like you stole it
RP = Royal Purple (I have tried several oils and no difference)
Try SEAFOAM if it really bugs you. THEN run Top Tier fuel + a bottle of Techron every now and then to help keep carbon down so it won't come back.
Lots of great info on this in the Chevy Talk Website. Search CSK or Cold Start Knock in the 99 up truck section. You will learn all you want to know. My advice is to drive it like you stole it
It is NOT a blown head gasket. You're saying I've had a blown head gasket for over 14months while getting on the car HARD many times in that period without any heating problems or other issues and was sold to me this way by the dealer?
I may not be an expert yet, but I do know enough to know that much.
I may not be an expert yet, but I do know enough to know that much.
My car also does it...its quite annoying for the first couple mins of it running.
But it goes away after it warms up. I've had people come up to me and tell me that I have a rod knocking
But it goes away after it warms up. I've had people come up to me and tell me that I have a rod knocking
Staging Lane
Joined: Oct 2006
Posts: 83
Likes: 0
From: Iowa
Easy mistake to make, I was responding to tons of people quickly! Sorry man!
I've been thinking it's just normal noise (although everyone who says its normal claims that it goes away after the car warms up), or the header gasket on the passenger side. You sir, could be correct!
Although, I'm not the only one that doesn't read, for the 9999th time...
IT DOESN"T GO AWAY AFTER THE CAR WARMS UP!!!
Definitely appreciate the suggestions guys, I'm fairly convinced that it's nothing MAJOR wrong mechanically.
if it dosnt go away when car warms up, then its prolly a header gasket. try to feel around the passenger side without burning urself. sometimes you can feel it push out exhaust. i doubt its piston slap if it dont go away.
TECH Resident
Joined: Oct 2005
Posts: 781
Likes: 0
From: Taxme, Ohio
Staging Lane
Joined: Oct 2006
Posts: 83
Likes: 0
From: Iowa
Thanks again.
Royal Purple - a synthetic motor oil. You might have seen the decal on some STB.
I think there's a sticky for acronyms somewhere around here.
I think there's a sticky for acronyms somewhere around here.
Teching In
Joined: Aug 2005
Posts: 40
Likes: 0
The sites below talk about it, people are pissed everywhere, just google "piston slap". My 02 2500HD (LQ4) has done it since day 1, 150,000 miles ago. My 99 ls1 doesn't.
Ever heard the saying "Chevy - Like a Knock"
http://www.lemonlaw.com/gm-engine-problem.html"
Ever heard the saying "Chevy - Like a Knock"
http://www.lemonlaw.com/gm-engine-problem.html"
My car has 86K on it and has had a "clomp clomp clomp" sound on cold start since I got the car at 32K 2 years ago. I drive it daily in the extreme cold and heat of the summer too and its never gotten worse or seemed to cause any problems. car still has great compression.
The piston slap site is funny imo.. guys freaking out because of slight scoring of the cylinder walls. funny but every engine I've ever torn down has scores in the cylinder and wear on the piston skirts. Hell I have stock ford 302 and 351 pistons as well as a couple LT1 pistons stock and aftermarket as paper weights and book ends. they all have wear marks on the skirts. So the skirt hits the cylinder walls regardless just on the LS1's there is just enough to make some audible sound when its cold.
The piston slap site is funny imo.. guys freaking out because of slight scoring of the cylinder walls. funny but every engine I've ever torn down has scores in the cylinder and wear on the piston skirts. Hell I have stock ford 302 and 351 pistons as well as a couple LT1 pistons stock and aftermarket as paper weights and book ends. they all have wear marks on the skirts. So the skirt hits the cylinder walls regardless just on the LS1's there is just enough to make some audible sound when its cold.
Last edited by sixvi6-camaro; Feb 3, 2008 at 08:49 AM.