[TR] Oil pressure

[Stuart Greenwood]

The 100 psi oil pressure when the engine and oil are cold are an indication
that the relief valve open at 100 psi. 
When the engine and oil warm up if the
oil pressure drops below 100 psi then either (a) the relief valve is sticking
open  or (b) the pump cannot supply sufficient oil flow.
I presume that the
oil pressure drops from 100 psi to 50 psi as the engine warms up, say 5
minutes after the coolant temp has stabilized. 
It is difficult to pin point
the problem because it would appear that the engine rebuild might not have
been performed to a decent quality standard.  I have no knowledge of the TR6
engine but on engines that I have rebuilt there are blanking plugs that seal
of the oil passages after they have been drilled during manufacture and, if
you are not diligent and not familiar with the engine, these came easily be
left out.  This would necessarily cause an external oil leak , for instance
oil could be escaping into the timing chain case. 
I would start with the
simplest thing. Remove and inspect the relief valve for signs of the piston
sticking in the bore. If you are convinced this is not the problem then you
are faced with tearing the engine down... but make sure you do it yourself :
don't entrust it to a shop no matter how highly recommended
 

Stuart A
Greenwood
71 MK I Stag 71 MK IV Spitfire