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post #8 of (permalink) Old 11-09-2002, 05:38 PM
Way Outta Control
Join Date: Sep 1999
Location: usa
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Re: low compression in #2 only showing 89 lbs

As LEVE suggested, pop the top off and look.
You may see something in the valve action - like bent pushrod,
pushrod fell off, loose rocker etc.
Or, you may find the cam's gone flat - hopefully not that,
it's more work!

Believe it or not, I've seen cylinders with no pushrod on
the intake valve at all still give some compression.
The suction action of the piston can lift the valve enough
to get a small gulp of air at cranking.
I wouldn't believe it if I hadn't seen it.

Bent pushrod? Make sure the valve still operates freely.
One trouble lately is the MTBE in gasoline forms a soft carbon,
and makes valves stick, bending the pushrod.

Saw it recently on a 454 with less than 250 miles on it.
3 pushrods bent like pretzels.
No it wasn't running too rich either, TBI. I think, but
not sure, since the truck sat for about 6+ months or so until
the engine was built, the MTBE in the near full tank chemically
changed into something that caused the excessive carbon.
The carbon was strange too. Usually carbon is a hard substance,
this was a crumbly, almost soft, stickey stuff. It felt soft,
porous, but was hard enough to scratch glass. I've heard
about it before, but this was the first time I saw it.
We had to pull both heads and completely redo them, guides and
all. Guides looked like you could drive a truck through them.

Let that be a lesson for all, if you store something, get
that "environmentally friendly" cancer causing MTBE laden
gas out of the tank. It goes bad fast.

If everything looks good, do what Taz suggested, pressurize
that cylinder and see where the air goes. A leak down tester
is almost the same thing, just has a gauge to see how bad is
bad - you know it's bad, you just need to know why.
RRich is offline  
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