Triumph Repair: oil pressure, crankcase pressure, vent pipes

Question
'76 Spitfire recently rebuilt engine.  Last week the oil pressure sensor "leaked"
under pressure and blew out 3 quarts of oil in a heart beat.  Ok, it was 30 years
old but oil seems to be blowing out the dip stick.  I've tried "tightening" up the
stick & replacing the little felt but...  no joy.
any thoughts?  Thanks, Jim

Answer
Hi Jim,
The oil pressure on your gauge nor sending unit has nothing to do with crankcase pressure that forces out past a dip stick.

Oil pressure on the gauge is pressure that it built up between the oil pump and the engine bearings.

Crankcase pressure that blows out a dip stick is pressure that is built up in the crankcase by piston ring "Blow by". Some pressure is normal and relieved by crankcase vent pipes either to the intake manifold or air filter.

When that pressure is excessive you need to do either a "Piston ring leak down test" or a "Wet and Dry Compression test".

First check to see that the vent pipes are in place and clear then purchase either a leak down tester or a compression gauge and run the tests on the rings.

If you chose to run the tests purchase either one of the tools and let me know and I will go over the test procedure for you.
Howard