Panheadache
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kell
- Member
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- Joined: Fri Aug 23, 2002 10:05 pm
Panheadache
I bought a panhead that had been rebuilt on the top end but they did something wrong with it. It blows oil out the front cylinder. Took it to a mechanic that did a lot of work and accomplished very little. He did a hone, new rings, exhaust valve guides and seals, made no difference. I don't think he even did a compression test before taking the thing apart. So I did that... 130 psi rear, 112 front. Put some oil in the front cyl to see if it's the rings, still 112. Not the rings. (Also, it broke a rocker arm on the front exhaust valve after I got it back from the mechanic.) What's next, should I try a blowdown test? Any suggestions?
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Cotten
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Re: Panheadache
There are two common places for oil to come from: Around the outside of a valveguide, and at the headgasket where the head drains to the cylinder.
The latter is the easiest to fix: plane the head flat, and properly torque it when re-assembled. (This shoulda been done to both heads in the first place, as the headbolt inserts are nearly always protruding, and it is the nature of an aluminum head to distort over the ports as well.)
The guidebore situation comes from hasty un-cleaned removal of earlier guides, thus scoring the bore in the head. Sometimes merely a proper gasket would have prevented the problem, but often the bore must be honed, and fitted with an oversize guide. Unfortunately this also usually sinks the seat out of sight when it is cut to correct to the new alignment.
Good luck.
The latter is the easiest to fix: plane the head flat, and properly torque it when re-assembled. (This shoulda been done to both heads in the first place, as the headbolt inserts are nearly always protruding, and it is the nature of an aluminum head to distort over the ports as well.)
The guidebore situation comes from hasty un-cleaned removal of earlier guides, thus scoring the bore in the head. Sometimes merely a proper gasket would have prevented the problem, but often the bore must be honed, and fitted with an oversize guide. Unfortunately this also usually sinks the seat out of sight when it is cut to correct to the new alignment.
Good luck.
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BIGAL
- Junior Member
- Posts: 3
- Joined: Mon Sep 09, 2002 2:33 pm
Re: Panheadache
you didn't say where the oils is coming from--out the ex-pipe
could be where the spring sits down on the head--very thin area over the ex.port----if its coming from the outside check where the cover inserts holes that are drilled into the head when they were made--i had one that came thru in the lower part of the ex-spring area under the first fin--from running in too long of screws to hold the cover on.
could be where the spring sits down on the head--very thin area over the ex.port----if its coming from the outside check where the cover inserts holes that are drilled into the head when they were made--i had one that came thru in the lower part of the ex-spring area under the first fin--from running in too long of screws to hold the cover on.