Lifters frequently fail stuck open. They get a bunch of carbon in them from
grubby oil or other deposits. There's really no magic goop you can put in an
engine to fix it. If you're going to keep the thing you have to fix it
right.
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On Behalf
Of Timothy F. Murphy
Sent: Monday, July 05, 2004 5:44 PM
To: 'FOT'
Subject: Small block Chevy question
My son (and partner on the race car project) has a Chevy pickup with a small
block Chevy (350 C.I.D.) It suddenly started "knocking" when he started it
a couple of days ago. It was quite warm, about 90, and the oil was really
thin, I think it was either 5W-30 or 10W-30. The knocking would seem to
come and go in intensity. Today we pulled the valve covers to have a look
at the rocker arms, springs and push rods. All looked normal. I listened
with the electronic stethescope but couldn't find anything definitive. We
pulled the plugs, which looked okay other than some carbon fouling on a
couple. Then we did a compression check and had 0 compression on #4. I set
it to TDC on #4 and the exhaust pushrod was still tight. I loosened the
rocker nut by 1-1/2 turns and then had about 30#'s compression. I'm
quessing either a very badly carboned up exhaust valve from a lifter
sticking "open" or a burnt valve from the same condition.
Question: How does a lifter "stick" all the way pumped up?
The cam and lifters were new on a rebuild about 1-1/2 years ago. Does
the analysis of the problem sound right? We're thinking of pulling the
intake manifold and head, renew the lifters and grind/replace the valves.
An alternate solution is to try dumping some "Sea Foam" in and hoping. Any
thoughts??
Thanks,
Tim
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