C3 Vette Registry - The Best Resource on the Net for C3 Vettes! C3 Vette
Forums -> C3 Engines
Not Logged In! Login or Register!  Users Online: 27 / Help 
Features  Find C3 Parts on ebay in only 2 or 3 clicks!  | Add YOUR C3 to the Registry

Supporting Vendors
VetteBookStore.com
Volunteer Vette Products
Bair's Corvettes
CorvetteClothing.com
Mid America Motorworks

C3 of the Month
None Current
Enter Yours Today!
Online C3 Show
13
C3s are Registered

Vanity Plates
CE82 Vet
vettejack
Featured Links

Buy Now
Corvette by the Numbers
Corvette by the Numbers


Corvette Magazine - $19.99 for 8 issues
Corvette Magazine
Only $19.99 for 8 issues


Collector's Originality Guide Corvette 1968-1982 (Paperback)
Collector's Originality Guide Corvette 1968-1982 (Paperback)


Corvette: America's Sports Car Yesterday, Today, Tomorrow (Hardcover)
Corvette: America's Sports Car Yesterday, Today, Tomorrow (Hardcover)



| Hide Signatures and Profile Pics

 New Topic New Topic Post Reply Reply New Poll New Poll Search     Search Page [1]  
5/11/11 9:50pm - Original Message: 'L82 piston slap'
lucky1357
Former Member
- Send Private Message


uncasville, CT - USA

Vette(s):
1978 Silver Anniv L82

Joined: 5/7/2011
Posts: 19
My 78 has an annnoying knock. Exhaust is new....manifolds and back. Ive been told L82s that yr were known for piston slap.....any input on this.?
 Reply Reply  Quote Reply w/Quote
 
Support C3VR!
Suport our advertisers
5/11/11 10:45pm - Reply: 'L82 piston slap'
Adams' Apple Lifetime Member
Lifetime Member
Moderator
- Send Private Message


Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19449
I've never heard that about the L-82 of any year, but I s'pose it's possible. The C4 model L-98s are BAD slappers when cold...just a fact. Doesn't hurt anything on them, tho.
Does yours only do it when cold, or does it have this noise all the time?
IF all the time, does the noise change when it warms up, or stay the same?
Does it sound like only one piston making the noise?

Piston "slap" is what happens if there is a little too much clearance between the piston and the cylinder bore. When the piston reaches TDC(top dead center) OR BTC(bottom dead center), it will rock in the bore, and create a noise as the piston barrel  hits the bore wall...kinda like a diesel engine running, but not as loud, or constant. Most of the time, this doesn't hurt anything. If it is really bad, it could eventually break the piston.


____________________________________
Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
 Reply Reply  Quote Reply w/Quote
5/12/11 9:13pm - Reply: 'L82 piston slap'
lukesvette Lifetime Member
Lifetime Member
- Send Private Message


HOWELL, NJ - USA

Vette(s):
1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.

Joined: 5/18/2004
Posts: 6804
My wife got piston slap me in da face!!Big smile

____________________________________
LukesVette Homepage
Veteran of Operation Iraqi Freedom
101st Airborne(AirAssault!)
God Bless America

Support Our Troops


     
 Reply Reply  Quote Reply w/Quote
5/12/11 10:24pm - Reply: 'L82 piston slap'
dskopp
Former Member
- Send Private Message


Oak Creek, WI - USA

Vette(s):
1981 Great White Shark. Red Interior, 350/190hp. PS, PB (SS), A/C CC, T-Tops, Going to remain as Stock as possible. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vetts Car Club. 175,000 Original miles!!

Joined: 5/21/2008
Posts: 1956
Are you sure it is piston slap and not a mechanical fuel pump noise??  That Luke guy up there ^ !!  He stole my answer!!
Dan


____________________________________
          



(click to see a larger image)
 Reply Reply  Quote Reply w/Quote
5/13/11 6:07am - Reply: 'L82 piston slap'
lucky1357
Former Member
- Send Private Message


uncasville, CT - USA

Vette(s):
1978 Silver Anniv L82

Joined: 5/7/2011
Posts: 19
actually.....just changed the fuel pump and its still there.Dosnt seem to be anything serious....just more anoying than anything....
 Reply Reply  Quote Reply w/Quote
5/13/11 11:23am - Reply: 'L82 piston slap'
manchestershark Lifetime Member
Lifetime Member
- Send Private Message


Equinunk, PA - USA

Vette(s):
1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.

Joined: 10/31/2007
Posts: 1895
Smile Put a bottle of S.T.P. or equivilent in the oil. Not to good for pistion skirts or the jug openings.

____________________________________

Click on image for full view
 Reply Reply  Quote Reply w/Quote
5/14/11 9:34am - Reply: 'L82 piston slap'
kstyer Lifetime Member
Lifetime Member
Moderator
- Send Private Message


CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!

Joined: 12/2/2003
Posts: 6410
Even with a new fuel pump, it could be the fuel pump push rod.  A worn rod will do this.  Pinch the fuel pump suction line for a minute or two.  If the noise stops before you run out of fuel, replace the rod.    Still could be a piston.

____________________________________
On the "Tail of the Dragon"
(some day, no strike that, October 2008 it turned red, still in progress!)

(click either image to see a bigger version)
 Reply Reply  Quote Reply w/Quote
5/14/11 10:20am - Reply: 'L82 piston slap'
Adams' Apple Lifetime Member
Lifetime Member
Moderator
- Send Private Message


Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19449
I just thoughted of sumptin else....it could be the dadgum heat riser valve. Those things can flutter really bad, and sound like an engine noise, especially the vacuum controlled ones.

____________________________________
Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
 Reply Reply  Quote Reply w/Quote
5/14/11 11:00am - Reply: 'L82 piston slap'
lucky1357
Former Member
- Send Private Message


uncasville, CT - USA

Vette(s):
1978 Silver Anniv L82

Joined: 5/7/2011
Posts: 19
will try pinching the fuel line at the pump.....and the heat riser isnt coming into play i dont think...it was disconected when i bougt the car.....and its frozen open.....kinda stumped with this....i work in a new car dealership and have my techs do the work on my vette....one of them was with chevy in the late 70s....he says just drive the car....its nothing to worry about...oil pressure is good....car has plenty of power....only has 32 thousand miles on it
 Reply Reply  Quote Reply w/Quote
5/14/11 8:22pm - Reply: 'L82 piston slap'
Per4mance Lifetime Member
Lifetime Member
- Send Private Message


Morganville, NJ - USA

Vette(s):
1971 350 270 hp roadster millivanilli red, black interior, white rag top, white hard top, I've had it 18 years and intend on giving it to my son for his 25th birthday(another 18 years from now)

Joined: 1/25/2009
Posts: 92
Rut roh sounds like carbon knock to me ....but there is a good remedy for this.Pull all the plugs and get some EOS at the gm dealer,fill all the spark plug holes with it and let it sit for 72 hours and then turn the motor over with the plugs out(it will be messy) put an old set of plugs in and let the motor warm up and then go hammer on it for a while put the fresh plugs back in and you should be in good shape  

____________________________________
 Reply Reply  Quote Reply w/Quote
 New Topic New Topic Post Reply Reply New Poll New Poll Search     Search Page [1]  
 Forums -> C3 Engines
(Moderator: Adam Wartell, Norsky, Adams' Apple)
 

 
Official C3 Vette Registry Community:
Home | Forums | Email | Who's Online | Clubs | Events | Member Stats

Other Official C3 Vette Registry Areas:
Members | Research | Shop | My Account | About C3VR
 

Corvette is a registered trademark of the General Motors Corporation(GM) & Chevrolet Motor Division. Vette Registries, LLC is responsible for all site content (except for member submitted content or where otherwise noted) and does not claim or imply that Chevrolet or GM is responsible for Official C3 Vette Registry content. Vette Registries, LLC is independent from GM and is not affiliated with, sponsored or supported by GM.  Copyright/trademark/sales mark infringements are not intended, or implied and are in fact used to support GM, Chevrolet and Corvette

Official C3 Vette Registry content is Copyright 2001-2017, Vette Registries, LLC. Content may not be reused without written consent. All Rights Reserved. NS

Corvette (Vette) Model Years on this site: 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 30