RE: [ST] High Mileage - Oil consumption

["Rick & Joyce" <rnjwes@xxxxxxxxxxx>]

John wrote:
> Startup and on/off throttle is most often the valve stem seals.
> However, the valve stem seals usually wear out because the 
> valve guides are worn allowing the valve stem to wiggle too much.

Rupert,
	No argument with John's explanation.  I might add that smoking
from bad stem seals will be worse on startup (when oil seeps past the
bad seals, accumulates and is burned after the engine is started) and on
deceleration (where high vacuum sucks oil past leaky intake valve
seals).  
	That said, while it's not unknown for Triumphs to suffer valve
stem &/or stem seal problems, I've seen more oil consumption from rings
not being seated to the cylinder walls.  There are about 34k miles on my
'01.  It typically uses ~1qt in 5k miles.  I'm not worried about that
level of consumption.  OTOH, a friend's '03 uses *at least* a qt. in 1k
miles.  I wouldn't put up with that.

> Does anyone have the full story on the bad breather valve and seal?
	IIRC, the breather oil slingers were originally of a composite
material.  Some of them weren't completely centric at the oil sealing
surface causing premature seal wear.  Failure of this seal (or a
left-side, engine-running tip-over) may result in an oiled airbox /
filter.  In a chronic failure, oil will drip from the airbox drain hose.

	The replacement parts are cast aluminum and the sealing surface
is machined to much better tolerances.
HTH,
Rick in Oregon
'01 Sprint ST


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