LT1 noise
Thread Starter
5th Gear
Joined: Jan 2011
Posts: 5
Likes: 0
LT1 noise
I have a 92 LT1with 82,000. Always been maintained and no evidence of being beaten. Has good oil press. @ idle about 60 lbs. cold, 45 lbs warm.
@ 3000 rpm under load, sounds like wrist pins are loose. Maybe even rod bearings. Oil pressure is always good. Once engine is warm, both coolant and oil temp, problem seems to go away. Are these engines normally just noisey until they reach oper. temp? I am guilty of running a lower octane fuel from time to time. Problem doesn't seem to be getting worse. Runs great and will still pin you back in your seat. Anyone have any thoughts?
Thanks.
@ 3000 rpm under load, sounds like wrist pins are loose. Maybe even rod bearings. Oil pressure is always good. Once engine is warm, both coolant and oil temp, problem seems to go away. Are these engines normally just noisey until they reach oper. temp? I am guilty of running a lower octane fuel from time to time. Problem doesn't seem to be getting worse. Runs great and will still pin you back in your seat. Anyone have any thoughts?
Thanks.
Thread Starter
5th Gear
Joined: Jan 2011
Posts: 5
Likes: 0
I'm just guessing at that. It's right at the middle increment or a little above. I just hate the thought of tearing this engine down to try to find the issue. Doesn't use any oil. Runs smoothly. I just can't tell if it's a wrist pin, rod bearing or in the valve train. Sitting still, you can rev it up and you won't hear a thing. On the road is when it's noticeable at about 3000 rpm and above.
Safety Car
Joined: Dec 2008
Posts: 3,588
Likes: 10
From: North New Jersey
Mine makes noise (almost like light tapping but not really) when its super cold out (around freezing) when you bring the rpms up above 2500ish... I dont think anything is wrong, its just cold out... But when its warm or during the spring, summer and the fall it doenst make any noise... 
Pro
Joined: Mar 2005
Posts: 713
Likes: 62
From: Melbourne Fl.
I'll bet it's piston slap. It's pretty common in LT engines and even the early LS engines. It's not a concern though. It just sounds bad. My 96 T/A has always had this problem. It started shortly after i bought it new. I just baby it until the engine warms up.
Warren
Warren
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
I'll bet it's piston slap. It's pretty common in LT engines and even the early LS engines. It's not a concern though. It just sounds bad. My 96 T/A has always had this problem. It started shortly after i bought it new. I just baby it until the engine warms up.
Warren
Warren
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Thread Starter
5th Gear
Joined: Jan 2011
Posts: 5
Likes: 0
I have often heard this term "Piston slap". I'm not sure exactly what it is. I've had vehicles with wrist pins that were a little worn and still ran forever with no problem. They were just a noisy engine. Is this the same thing?
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
Piston slap they are referring too especially in the LS engines, is the piston is actually a little bit smaller than the bore and slightly out of round compared to the bore. This is to compensate for the expansion of the aluminum when it gets hot. Usually this is a non-issue but can be one from time to time.
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
FWIW.....my old 92 LT-1 had the same problem. It was determined to be exactly what has been pointed out....piston slap. From then on I just took a little extra time to warm up the engine and stopped worrying.
Burning Brakes
Joined: Oct 2009
Posts: 773
Likes: 2
From: Minneapolis MN
Start putting the best/highest octane fuel in your vette.These engines are designed to use thehigher octane so stop putting the cheap stuff in
Do this & see if problem goes away.I never had this issue/noise with my Lt1.Let us know if this fixes your problem
Le Mans Master
Joined: Oct 2004
Posts: 5,841
Likes: 19
From: CLT, North Carolina
Piston slap is a fairly common occurance in performance engines due to increased piston to bore clearance. Usual methods to quiet piston noise are tighter clearances, low taper wide skirts and offset pins all of which will actually hurt performance. If the noise is always there after a cold start but quiets when the engine warms up it is most likely harmless piston noise.
Safety Car
Joined: Dec 2008
Posts: 3,588
Likes: 10
From: North New Jersey
Like I said, no problems running regular gas...
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Running regular fuel is fine. The computer has a table in it that it uses to reduce timing when using lower octane fuel. It "knows" when lower octane fuel is used by looking at knock sensor activity.
The only "negative" is that the engine will have reduced power at high and WOT settings. For a daily driver...no big deal.
The only "negative" is that the engine will have reduced power at high and WOT settings. For a daily driver...no big deal.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
I have a 92 LT1with 82,000. Always been maintained and no evidence of being beaten. Has good oil press. @ idle about 60 lbs. cold, 45 lbs warm.
@ 3000 rpm under load, sounds like wrist pins are loose. Maybe even rod bearings. Oil pressure is always good. Once engine is warm, both coolant and oil temp, problem seems to go away. Are these engines normally just noisey until they reach oper. temp? I am guilty of running a lower octane fuel from time to time. Problem doesn't seem to be getting worse. Runs great and will still pin you back in your seat. Anyone have any thoughts?
Thanks.
@ 3000 rpm under load, sounds like wrist pins are loose. Maybe even rod bearings. Oil pressure is always good. Once engine is warm, both coolant and oil temp, problem seems to go away. Are these engines normally just noisey until they reach oper. temp? I am guilty of running a lower octane fuel from time to time. Problem doesn't seem to be getting worse. Runs great and will still pin you back in your seat. Anyone have any thoughts?
Thanks.
It is common sense, but I have read also that you should not push the car until the oil temperature is something like 125 deg or so.