A blowdown test will reveal a lot more, but I would almost guarantee there
are ring problems. I had some oil burning engines that I couldn't understand
and eventually called the piston manufacturers who sent an engineer out. He
diagnosed incorrectly made piston rings, naturally the manufacturers
wouldn't actually admit this but replacing the rings cured the problem and
they were certainly at fault.
John Kipping
----- Original Message -----
From: "Brad Kahler" <brad.kahler@141.com>
To: <fot@autox.team.net>
Sent: Thursday, October 17, 2002 10:04 AM
Subject: generic question on compression checks
> Amici,
>
> This isn't really Triumph related (other than its a tow vehcile!) but I'm
> looking for guidance on an engine problem.
>
> We had an engine rebuild in our Jeep last spring and over the
> course of the next year we had over heating problems, lack of power
> and apparent blow-by.
>
> We took it back to the rebuilder multiple times to try and get the
> problem(s) corrected. Never did have much luck. However, trying
> to get past the state emissions test last month this almost new motor
> failed miserably.
>
> Here are the apparent symptoms. OIl in the air cleaner coming from
> the valve cover. Compression check shows approximately 140-145
> across all 8 cylinders at first. However on the 3rd revolution of each
> compression check (which is what the manual says to check for) the
> pressure drops to 115-120 but comes back up to 140-145 on the 5th
> revolution.
>
> This doesn't sound like a piston ring problem to me. It would seem
> to be more of a bad cam. The cam shaft was replaced, the heads
> were given valve jobs. Basically it was a complete engine rebuild.
>
> Any thoughts on what to look for? Should he just pull the heads and
> cam on the assumption that the rings are probably ok? Or does this
> sound like a ring problem AND a valve/cam problem?
>
> Any help on this would be greatly appreciated!
>
> Thanks
>
> Brad
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