[TR] Burned Exhaust Valve

[Brian Jones]

Art,I was intrigued by your issue and in a quick web search found this -to
me- helpful link.

http://www.aa1car.com/library/ar1192.htm

It explains, as did Randall, that exhaust valves must be seated properly.
They get much hotter than inlet valves and dissipate heat through their
contact with the valve seat. So poor seating = more heating, sometimes to
the point of failure. So if the guide is OK, how is the seat?

Water jacket failure around that cylinder would also cause heat build up.
You mention the head gasket was OK. Did you use silicone goop in its
installation to seal it? My PO used to. I've had the head off twice (for
different reasons) and each time have fished out with forceps both blue and
orange gobs of goop in the water channels. He clearly had no brand loyalty
where goop was concerned.

Other reasons for failure are discussed in the link: too lean mixture,
detonation, pre-ignition, among others.

Brian

On Tue, Sep 15, 2009 at 5:38 PM, <akgraves at cox.net> wrote:

> Thanks for your responses.
>
> Joe, there was some smoke reported when I accelerated.
>
> Jim, I think the valve guide is okay.  With the springs removed, I can put
> my finger over the top of the guide, pull the valve down and the suction
> will pull the valve back up.  This is consistent on all valves.
>
> Randall, I will leak test the cylinders to hopefully determine where oil is
> coming from.  To do this I will pour a small amount of oil (Marvel Mystery)
> onto the top of pistons #5 and #6.  I'll test the others this way also.
>  Maybe that will tell me something.
>
> The oil loss and burned valve are probably related.  I'll post an update.
>
> Art Graves
> Tulsa, OK
> 1976 Triumph TR6
>
>
>
>
> > Thinking that the head must not have been torqued properly, I began
> cleaning
> > my tools and shop for the next day.  Then I noticed a gaping hole in the
> #6
> > exhaust valve.  I removed it and there is a 5/16'' chunk missing!  My
> > question
> > is what could have caused that?
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