Engine Guru's Chime In
Thread Starter
Racer
Joined: Jun 2001
Posts: 422
Likes: 0
Engine Guru's Chime In
Last night I left to go to a local show and about 2 miles from the house the BB sounded like someone removed the spark plug wire. so this morning I dropped off to a local shop for advice. a compression test showed 0 compression in # 5 cyl.
as of 5:00 today they had not removed the valve cover and can't until tomorrow so I thought we would play a guessing game.....
here's a hint. I have actually heard a slight tapping in the valve cover since the engine was rebuilt 1500 mi ago but never noticed any problems until now.. So what is it ? Head,piston, etc,etc :nopity :nopity
as of 5:00 today they had not removed the valve cover and can't until tomorrow so I thought we would play a guessing game.....
here's a hint. I have actually heard a slight tapping in the valve cover since the engine was rebuilt 1500 mi ago but never noticed any problems until now.. So what is it ? Head,piston, etc,etc :nopity :nopity
Le Mans Master
Joined: Aug 2000
Posts: 6,362
Likes: 7
From: Brazos TX
Cruise-In IV Veteran
Cruise-In V Veteran
Re: Engine Guru's Chime In (71DropTop)
I could be a broken rocker stud or the nut just backed off and the pushrod slipped off the rocker arm. This would have to be on an intake valve. That's my guess. Hopefully it will be an easy fix.
Burning Brakes
Joined: Oct 2002
Posts: 813
Likes: 0
From: death to the southeast
Re: Engine Guru's Chime In (burners)
that definately sounds like a valve train problem. If there is a problem with either valve you could lose all compression. The pressure from the engine could be what's causing the noise. Maybe something is being blown against the valve cover, i.e loose nut or valve stem piece.
Melting Slicks
Joined: Jun 2001
Posts: 2,340
Likes: 2
From: Moro IL
Re: Engine Guru's Chime In (burners)
I could be a broken rocker stud or the nut just backed off and the pushrod slipped off the rocker arm. This would have to be on an intake valve. That's my guess. Hopefully it will be an easy fix.
:cheers:
Pat Kunz
Le Mans Master
Joined: Apr 2001
Posts: 5,941
Likes: 281
From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
Re: Engine Guru's Chime In (71DropTop)
My boss recently had a bad nut on his 454 in a Dually. It actually took him a while to determine the exact problem. He first thought a head gasket had blown and actually pulled the head. He eventually located the bad rocker nut, but also replaced the stud to be safe.
Mark B.
Mark B.
Instructor
Joined: Nov 2002
Posts: 228
Likes: 0
Re: Engine Guru's Chime In (71DropTop)
You said that you had "0" compression on #5 cylinder. If you had good compression on#3 that rules out blown head gasket. So with "0" compression you have to have a valve stuck open or a hole in the piston. I would think a stuck valve and would bet its the exhaust. If you had new valve guides installed one might have guiled. The ticking noise would be the push rod slack caused by the valve stem not making staying in contact with the rocker. If the adjusting nut backs off the valve stays closed. Let me know if I guessed right. Good Luck on solveing the problem.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
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
Le Mans Master
Joined: Aug 2000
Posts: 6,362
Likes: 7
From: Brazos TX
Cruise-In IV Veteran
Cruise-In V Veteran
Re: Engine Guru's Chime In (71DropTop)
That's good news. What type of rocker is it and who made it? Many times a failure is due to improper heat treat or a flaw in the material. It is very difficult to predict.