Paging LT1 valve train gurus
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Burning Brakes
Joined: Sep 2001
Posts: 1,011
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From: Jupiter Florida
Paging LT1 valve train gurus
I need your help diagnosing a problem. I've been getting this kind of 'woot woot' noise on startup that diminishes as the engine warms up. It's finally gotten loud enough initially that I'm getting worried.
I've pulled the rocker cover and tried to isolate the sound with a stethescope. As near as I can tell over the normal valve clatter, the sound is loudest near and seems to be in time with the #8 cylinder exhaust valve.
Everything appears to be in good order with the pushrod and rocker. As the engine warms I begin to get some very light smoke or vapor rising from that area.
I'm thinking it must be a worn (cracked?) valve guide because eventually the sound lessens to the point where you really have to listen for it, maybe due to better sealing as a result of thermal expansion or increased oil flow. Can a small amount of exhaust escaping through a worn/cracked exhaust valve guide make noise or am I completely on the wrong track here?
Your help is greatly appreciated.
[Modified by rocketfinger, 3:53 PM 6/17/2002]
I've pulled the rocker cover and tried to isolate the sound with a stethescope. As near as I can tell over the normal valve clatter, the sound is loudest near and seems to be in time with the #8 cylinder exhaust valve.
Everything appears to be in good order with the pushrod and rocker. As the engine warms I begin to get some very light smoke or vapor rising from that area.
I'm thinking it must be a worn (cracked?) valve guide because eventually the sound lessens to the point where you really have to listen for it, maybe due to better sealing as a result of thermal expansion or increased oil flow. Can a small amount of exhaust escaping through a worn/cracked exhaust valve guide make noise or am I completely on the wrong track here?
Your help is greatly appreciated.
[Modified by rocketfinger, 3:53 PM 6/17/2002]
Melting Slicks
Joined: Jun 2001
Posts: 3,444
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Re: Paging LT1 valve train gurus (rocketfinger)
Why not put that cyl at TDC and take off the rocker and valve spring. Get a new seal as you will probably have to remove it. Wiggle it around and see if you have any play. You shouldn't feel any. Not feeling any doesn't mean all is well though, as you said you could have a crack.
Instructor
Joined: Apr 2002
Posts: 126
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From: port saint lucie florida
Re: Paging LT1 valve train gurus (Jay Axson)
not that it is related but , i had a truck with the same symptom. turned out to be a pilot bearing at the flywheel/crank. does your noise change with chutch pressure/ engine load?....
