Re: Tom's Many Problems

[jlandry@domain.elided (John A. Landry)]

In a brilliant stroke of genius, Steve Stegmann
<stegmann@domain.elided> blurted out:

>I wouldn't even look at the valve guides if the compression is good.  If
>anything is wrong with the valves, it won't hold compression.  If the 
>valve guides leak a major amount, the guides will probably be loose and 
>the valves won't hold compression.

Steve,

I once worked on a Honda motorcycle that had great compression test
results, yet upon disassembly, the back side of the exhaust valves were
*caked* with burned oil residue and to a lesser degree the intake valves.
It took many hours of work wire brushing off the nasty buildup.  It turned
out the umbrella style valve stem seals had become cracked and brittle and
had lost their sealing ability.  The valve guides weren't worn past
specs... just the seals were toast.  This motorcycle did burned a moderate
amount of oil between changes, yet not enough to be visible out of the
tailpipe.  The spark plugs showed moderate signs of oil burning with the
typical hard dark carbon deposits.  New seals completely eliminated the oil
consumption.

This experience plus Tom's symptoms lead me to feel the valve guide seals
are a strong culprit.  I can't say why only two opposite cylinders exhibit
the symptoms, but I don't think it's the carb.

Attention Tom M.: What year engine was this *originally* and does it have
EGR?  I just thought of something else that I'd like to think about.

Regards,

John L.
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