I once read that the BMC 1800 large, front wheel drive sedan, produced in
the early seventies, experienced a large number of engine failures when it
was first introduced. The failures were due to poor lubrication related to
low oil pressure. After a lot of troubleshooting, they found that the
problem was caused by a miscalibrated dipstick. No, this is not my wife's
pet name for me, but rather a dipstick with a "full" line that was too high.
Owners would fill the engine with oil, to the level shown on the dipstick,
but the level was then so high that the crankshaft throws were below the
surface of the oil in the sump as the pistons approached bottom dead center.
As you can imagine, the crank rotating at highway speeds whipped the oil to
foam and the resulting air entrainment caused the oil pump to cavitate, thus
delivering less than optimum lubricant quantity and pressure to the engine.
Maybe this is happening to your TR6?
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