LS1derfull

Has anyone here diagnosed exactly what causes piston slap in our motors? They only run .0015"-.0025" piston to wall and they are a full skirt design piston, WTF? Is it wrist pin bending or clearance issue? I dont buy that it is cylinder bore not being round. My bores are visualy perfect and they seal very well also, so what is causing this noise?
Anyone?

Patman

TTT, cuz I'm curious too.

Rhode Island Red

iTrader: (2)

This is what I have via TSB's from GM

pretty much its also basic physics... the engine is made up of different metals... different metals have different expansion rates... simplest reason


GM Tech Bulletin

Higher Than Expected Oil Consumption (Replace Rings)
#01-06-01-023
Higher Than Expected Oil Consumption (Replace Rings)
1999-2001 Chevrolet Camaro, Corvette
1999-2001 Pontiac Firebird
with 5.7L Engine (VINs G, S -- RPOs LS1, LS6)
Condition
Some owners may comment on higher than expected oil consumption.
When checked,
the oil consumption could be in the range of 400-600 miles per quart
(700-1000
km/L).
Cause
The cause for this condition may be an interaction between the
piston rings and
the cylinder bore in vehicles that are operated at higher RPMs --
typically
manual transmission vehicles driven in a manner where the engine is
frequently
or consistently operating at greater than 3200 RPM.
Correction
A new set of piston rings is currently available through GMSPO. The
new rings
are part of a complete piston ring kit. Install only the number 2
compression
ring and the oil expander ring from the piston ring kit. All other rings
in the
piston ring kit should be discarded. The original number 1
compression ring and
the oil ring rails should be re-used in their original positions on the
piston.
All pistons should be used in the same cylinder bore.

Important
Do not dress or hone the cylinder bore. Nothing should be done to
change the
bore finish for this condition. Changing the bore finish may aggravate
the
condition.

Refer to the Unit Repair Manual for appropriate ring removal and
replacement
procedure.
The number 1 compression ring and the upper and lower oil expander
rails are
re-used because they are already broken in for the bore that they are
in. The
new number 2 compression ring is made with a very sharp edge that
will break in
quickly.
Changing only the piston rings noted, with no change in driving style,
should
change oil consumption to an acceptable level. Changes in driving
style that
reduce the amount of time spent at higher RPMs will also positively
effect oil
consumption.
In addition to the standard size piston ring kit listed below, a 0.25
mm
oversized piston ring kit is available. The oversized piston ring kit
should
only be used in those rare instances where the cylinder bore size has
been
machined larger to accommodate the 0.25 mm oversized piston rings.
Parts Information
Part Number
Description
Qty
88894299
Ring Kit, Piston
8

Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation
Description
Labor Time
J1307
Piston, Rod and/or Rings -- Replace, Both Banks
Use Published Labor Time

TSB #02-06-01-038
Engine Knock or Lifter Noise (Replace O-Ring) #02-06-01-038 - (12/02/2002)
Engine Knock or Lifter Noise (Replace O-Ring)
2001-2002 Chevrolet Camaro
2001-2003 Chevrolet Corvette
2001-2002 Pontiac Firebird
2002-2003 Cadillac Escalade, Escalade EXT
2000-2003 Chevrolet Suburban, Tahoe
2001-2003 Chevrolet Silverado
2002-2003 Chevrolet Avalanche
2000-2003 GMC Yukon, Yukon XL
2001-2003 GMC Sierra
with 4.8L, 5.3L, 5.7L or 6.0L V8 Engine (VINs V, T, Z, G, S, N, U -- RPOs LR4, LM7, L59, LS1, LS6, LQ9, LQ4)
Condition
Some customers may comment on an engine tick noise. The distinguishing characteristic of this condition is that it likely will have been present since new, and is typically noticed within the first 161-322 km (100-200 mi). The noise may often be diagnosed as a collapsed lifter. Additionally, the noise may be present at cold start and appear to diminish and then return as the engine warms to operating temperature. This noise is different from other noises that may begin to occur at 3219-4828 km (2000-3000 mi).
Cause
The O-ring seal between the oil pump screen and the oil pump may be cut, causing aeration of the oil.
Correction
Inspect the O-ring seal and replace as necessary. Use the applicable part number listed below. Refer to the Engine Mechanical sub-section of the appropriate Service Manual.

Parts Information
Part Number
Description
Qty

12557752
Seal-O/Pmp (O-ring)

(F and Y Cars)
1

12563963
Seal-O/Pmp (O-ring)

(C/K Trucks)
1

Parts are currently available from GMSPO.

Warranty Information
For vehicles repaired under warranty, use:

Labor Operation
Description
Usage
Labor Time

J1060
Pickup Tube and Screen - Replace
F Car
3.7 hrs

Y Car
4.3 hrs

Slowhawk

iTrader: (12)

Maybe your car has too much power and is scared of the Hawk

And Brian,whats up with the long explaination of oil consumtion

MyLS1Hauls

iTrader: (2)

I wonder if floating pin piston motors make this noise? Problem is, all of the floating pin pistons are forged and require more piston-bore clearance. I always thought the LS1 pistons were short skirt?

dis3as3d

The way it was explained to me, is that they designed the pistion to save weight. And they made the skirts too small so the pistion wants to turn sideways. This causes harder wear on the piston rings, and then you all know the consequences.

Jay 95WS6

well here's the deal the pistons are hyperutectic and when they are cold they are egg shaped and when they warm up the "round out", next the piston pin is "centered" in the piston so there is very little side thrust so it allowa the piston to "float" in the bore, also the skirt is very short which allows the piston to "rock when cold. LS1's also have a "light" ring pkg which doesn't hold the piston straight in the bore either. carbon on the top of the piston will make the noise more pronounced because of the imbalance. GM designed the LS1 this way kinda
like a race type motor so they could pick up alot of HP by getting rid of parasitic losses.

Jay

LS1derfull

Very good answer, i agree with all you said,thanks.
The only thing that bothers me is some are noisy and some are not, identical vehicles and years, so what causes this?
If i had bad machine work from GM than rings would not have sealed up like they have, power would be down too. I am curious what is causing this noise that didnt show up till approx. 15k ?

Jay 95WS6

that is most likely the carbon buildup on the pistons try running top engine cleaner through it it usually helps for about 10-15k miles

Jay