Date: Sun, 9 Aug 1998 18:30:59 -0400
Reply-To: James Wagner <wagner01@EROLS.COM>
Sender: Vanagon Mailing List <Vanagon@vanagon.com>
From: James Wagner <wagner01@EROLS.COM>
Subject: Bent Valve Part II
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Thanks to those who sent me advice on the first part of my stuck intake
valve episode.
Now I've removed the head and can see that the valve and head did make
contact, though only very slightly. There is a small scuff mark on the
piston (shiny aluminum in the sea of carbon) and no mark on the valve.
In order to get the van the one mile back to my drive way, I took out
the push rod to the stuck valve, and ran on three cylinders. I though
the van would just be a bit low on power and vibrate a lot, but it ran
horribly. It idled great and ran OK up to about 1800 rpm, but above
that it shuddered and stumbled. I suppose it was a lack of exhaust back
pressure, otherwise I'd think the cylinders would be pretty independent
of one another.
Anyway, there was about an ounce of oil in the cylinder with the stuck
intake valve (which I forced closed before I attempted to run on three
cylinders. I also disconnected the fuel injector wire). But otherwise
it looks fine. No scuff marks on the cylinder. I guess I should have
disconnected the exhaust valve also, since the oil probably was just
sucked up into the cylinder since the intake valve was not opening to
reduce the vacuum in the cylinder.
At this point I think I will try an old cylinder head and see if the
cylinder runs makes adequate compression.
I am still trying to determine what happened. I had replaced both heads
and driven less than 100 miles the previous week with only a short
episode of clanking sounds coming from the engine. I immediately
checked all the valves and the compression in the cylinders and
everything checked out ok. After driving it a bit more the sound
disappeared.
After a week of not driving the van, I started it, and went about a mile
down a flat road to a stop design. The engine just died. When I tried
to start it, the clanking sound was back. I check the valves and found
the #4 intake push rod longed between the rocker and the cylinder head
wall. The rocker was not contacting the valve and the valve was stuck
in the open position. When I removed the push rod, I found it bent.
Now that the head is off and I can't get the lifter out. The push rod
seems to have dented the wall of the cylinder the lifter slides in. I
think I'll hone the cylinder with a brake cylinder hone.
If anyone has any advice please let me know. My advice is pay very
close to those valves when replacing the heads. I think I had a small
window to avoid this problem, but I guess I needed to test the valves
for smooth movement.
Thanks,
--
James Wagner
PS Anyone know why disconnecting one cylinder makes the whole engine run
so poorly as opposed to just less power and more vibration.
