"William M. Gilroy" wrote:
> I took Tevor's advice and gave it a try with the diesel fuel. I
> positioned the pistons 1/2 way up the bore and filled the rest with
> diesel fuel. The second cylinder drained in about 1.5 hours,
> followed shortly by the number 1 cylinder. After about 2.25
> hours the number three cylinder was empty. Number four, the
> cylinder with the good compression had only leaked down about 1/2".
> After 5 hours cylinder 4 had leaked at most 1 inch, if that. Now
> the cylinders drained in the following order, 2,1,3 and 4 held
> the diesel.
That certainly gives a valid comparison between cylinders,
and might explain a bit if the drainage speeds match up to
the cylinders with bad compression.
However, I've used the diesel fuel test quite a few
times, and none of those values are actually very bad.
A brand new engine could do better, but I don't consider
1.5 hours to really be that bad. I have seen engines that
came in running, and would drain completely before your eyes,
a couple of minutes or so.
> I also filled the intake and exhaust ports with diesel. None of
> the exhaust valves leaked. The intake valves on cylinder 1, 2, and
> 3 leaked. They leaked slowly and the ports never drained.
The valves usually give a better seal than that, however
bad valves won't explain your dipstick-oil problem.
Can you see any defects on the valves, such as non-round
areas or sections that are a different colour? You might try
lapping them (only need basic tools) and seeing if that
will seal them up. That certainly doesn't qualify as a rebuild,
but if after a quick lapping they become watertight again,
I don't think that was a major valve problem.
> Looks like I will be pulling the engine over the next couple of
> weeks and getting it rebuilt. This really should not suprise anyone.
It surprises me a little. If having a top-notch engine
is something you want, go for it. But from my experience,
those drain times would not indicate a MAJOR problem. I
would snoop around a little more before comitting thousands
of dollars and weeks of your time to rebuilding it.
However, one caveat with the drain in the pistons trial
is that you are only measuring the ring seal at that
point. It is possible that the cylinders are scored or
out of round near the top or bottom of the cylinder.
Try repeating the test in the "bad" cylinder
at a few different places like near TDC, at BDC, and
so on. However, if you are getting an hour or so
before the diesel drains, look elsewhere.
I've said it before, but a lot of people on this list
have a REAL hair trigger for engine rebuilds. It seems
like the autox.team.net troublshooting chart would have
"rebuild engine" in almost every line. "Bad smell? Rebuild
engine. Rattle? Rebuild. Paint fading on block? Rebuild".
Rebuilding is always an option, it's always there, it
won't go away if you try other things. You might get away
with something simpler, seal it up, and get 2-3 more
years out of it before you *NEED* to rebuild. Consider
them free miles.
> The only problem I encountered was how do I get the diesel out
> of the number 4 cylinder and the head ports.
I usually siphon it out, and dry the rest with a towel. A
little won't kill you, that is actually why diesel fuel
is used for this test. It is resistant to gumming and
is a pretty strong cleaning agent, so it won't glue up
your rings like gasoline would if you used it instead.
--
Trevor Boicey, P. Eng.
Ottawa, Canada, tboicey@brit.ca
ICQ #17432933 http://www.brit.ca/~tboicey/
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