Knocking sound when cold: LT1, what cause?
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 7,858
Likes: 2
Knocking sound when cold: LT1, what cause?
My '95 has an audible mechanical knocking sound when warming up, originates around #8 cylinder area of engine, or so it seems. Once the coolant temp gets up to, say, 130 - 140 it seems to go away or at least you can't hear it anymore with the naked ear.
Is this something major? I have GMPP so if it is major I might be okay, if I ccan get them to buy off on the repair.
Is this something major? I have GMPP so if it is major I might be okay, if I ccan get them to buy off on the repair.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: Knocking sound when cold: LT1, what cause? (Lone Ranger)
hmmm... could be a slow to inflate lifter... or a noisy injector.
I doubt if it is a bearing...
another thought... if its a 6spd, the tranny could do it, too... I know mine is a bit noisier when first started.
I doubt if it is a bearing...
another thought... if its a 6spd, the tranny could do it, too... I know mine is a bit noisier when first started.
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
Re: Knocking sound when cold: LT1, what cause? (bogus)
Sounds a bit like a wrist pin. I had exactly the same noise and symptoms on my old 70 LT-1. Turned out that the excessive tolerance in the pin allowed the piston to "slap" the side of the cylinder walls. Made a knocking sound. When the engine warmed up and the metal in the pin expanded the niose went away. I sure would run it in to the dealer and get it documented. Even if they say it's ok, you will be covered down the road as you brought it to their attention and they didn't fix it or didn't fix it right.. Good Luck.
[Modified by ittlfly, 6:20 PM 11/17/2002]
[Modified by ittlfly, 6:20 PM 11/17/2002]
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 7,858
Likes: 2
Re: Knocking sound when cold: LT1, what cause? (ittlfly)
You're probably right about having them listen to it.
Sounds a bit like a wrist pin. I had exactly the same noise and symptoms on my old 70 LT-1. Turned out that the excessive tolerance in the pin allowed the piston to "slap" the side of the cylinder walls. Made a knocking sound. When the engine warmed up and the metal in the pin expanded the niose went away. I sure would run it in to the dealer and get it documented. Even if they say it's ok, you will be covered down the road as you brought it to their attention and they didn't fix it or didn't fix it right.. Good Luck.
[Modified by ittlfly, 6:20 PM 11/17/2002]
[Modified by ittlfly, 6:20 PM 11/17/2002]
