Trevor Boicey wrote:
>
> "William M. Gilroy" wrote:
>
> 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.
None were that bad. The rate they drained did corresponding with
their compression level. While the rate may not be bad, the
difference in the rate cannot be good. I would like them all
be like number 4.
>
> 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.
>
The valves look all right, no obvious discoloration at any point.
Lapping the valves will not stop the oil leaking along the guides.
Just how much oil is consider acceptable in the intake manifold?
I have oily deposits there.
>
> > 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 might give this a try. I would expect slightly different
results at the bottom of the stroke. None of the bores seem
to show any scoring.
Where else would I look? I was getting oil out the dipstick with
even with the valve cover vent disconnected. That should vent
any excessive crank case pressure. I would have to get a lot
of pressure in the crankcase to send oil out the dipstick. Since
the head gasket was not bad I would think it is the rings.
> 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.
If I have to replace the rings, or something on that order
I will most likely go with a complete rebuild to be on the safe
side.
>
> 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.
I wasn't worried about the diesel in the cylinders, it was the
smell. My garage is attached to the house and my wife does
not take kindly to me stinking out the house.
>
> --
> Trevor Boicey, P. Eng.
> Ottawa, Canada, tboicey@brit.ca
> ICQ #17432933 http://www.brit.ca/~tboicey/
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