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Re: [ST] Re: valves and oil consumption



Steve,

I've been following your explanation with interest and I
understand your concept of how the exhaust valve stem seal could
become damaged.  But doesn't most valve stem seal-related oil
consumption occur on the intake side due to the vacuum which
exists in the inlet tract?  I know there is a brief negative
pressure pulse which occurs just after the exhaust valves close
but otherwise the exhaust tract is under some pressure any time
the engine is running.  Once the engine is shut off, the oil does
puddle in the front of the head, where the exhaust seals could be
below the oil level there.  Wouldn't that leakage past the
exhaust stem seals, mostly into the exhaust ports, create an oily
tailpipe and a cloud of smoke after the engine was restarted?  Am
I missing something here?
Rick in Oregon
'01 Sprint ST
"NO Dawg"


- ----- Original Message -----
From: "Steven Kohlscheen" <Steven.kohlscheen@xxxxxxxx>
To: "Trump List (E-mail)" <ST@xxxxxxxxxxxxxx>
Sent: Tuesday, December 04, 2001 12:03 PM
Subject: [ST] Re: valves and oil consumption


> The clearance is checked between the valve stem and the cam
lobe.
> In my case I'm concerned the unusually tight tolerances were
not allowing
> the exhaust valve to completely close.  If this were the case
some of the
> combustions explosive effort could have seeped past the valve
head to valve
> seat mating, and this blowby could have caused some damage to
the valve
> seals, thereby creating a path for oil to be consumed.  Yes
Rube Goldberg is
> a favorite of mine, but I can see this happening.  Plus it
explains my last
> round of hard first starting issues.
>
> Steven "Dirty Dawg" Kohlscheen
> <<
> OK, I'd like to show my ignorance and ask: why do tight exhaust
valves make
> oil consumption go up?  An even more basic question, where on
the valves are
> the clearances actually measured?  You can tell I didn't do my
own 12,000
> mile service, can't you!
>
> Neil
> >>
>
>
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