Randall wrote :
> "The drop in oil pressure is
> quite alarming, but actually not too serious, there is guaranteed to still
> be oil flow through the main and rod bearings. A moderate drive
> home should
> be no problem."
Glenn C replied :
>
> Are you saying that the bypass valve will not "vent" the full
> flow of oil or
> that even low pressure is adequate to push the oil everywhere in a TR3
> engine?
Neither, really. The pressure relief valve cannot stick open any wider than
it was pushed by oil pump output less what went through the bearings, etc.
at the relief pressure. Even though the valve is capable of opening wider,
it never does so under normal operation.
So, there will always be some oil flow through the bearings. The main
reason that a constant oil flow through the bearings is necessary is to keep
them cool, but at moderate loads & rpm it doesn't take much at all to do
that. Maximum oil pressure is only required at high load & high rpm (and
probably not even then with modern oils).
There won't necessarily be oil flow to the rocker arms, but they should be
able to survive for many miles without oil flow, lubricated only by the oil
already present. In fact, I once drove an engine for over 10,000 miles that
turned out to have had the rear cam bearing improperly installed, so that
there was no oil flow at all to the rocker shaft. Some of the pushrods were
actually rusty, and the shaft was badly worn, but it ran !
Of course, I'm not suggesting that it's "good" to drive an engine with a
stuck relief valve ... only that it's not a calamity and it will most likely
get you home if you're gentle. No need to call the flatbed unless you
really want to.
Randall
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