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Re: [T3] Stretching valve stems?


On Mon, 2005-11-14 at 08:26, Matthew Jones wrote:

> 
> Ah, that makes a lot of sense. I lost exhaust #3 on a beetle at 65mph once. Very
> messy. High mileage engine that probably hadn't been well looked after.
> 
> Someone once told me the valve head was welded to the stem, and that's where
> they broke, because it was a weak point. Fits the symptoms but thinking about
> it they would never make them that way!
> 
> Would the exhaust tend to go first due to hot gas further eroding the brittle
> fatiguing zone ?
> 
> 
It is usually #3 that fails. That is the exhaust valve that runs the
hottest. 
Have you ever taken a piece of wire and bent it back and forth until it
broke? If you had measured it as you bent it back and forth, you would
have seen it grow in length and smaller in diameter as you bent it.

-- 
Russ Wolfe
'71 FB AT
'66 FB MT
'64 T34 (not running)
'65 T1 (not running)
'05 KIA Sorento SUV
russw@classicvw.org
http://www.classicvw.org

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