I have completed a forum ‘search’ under ‘oil pressure’ which produced volumes of discussion about different oil grades, but only one information about what to expect for normal running oil pressure – 40 to 80 psi.
So my questions for a P Type engine is what oil pressures should be expected for a fully-up-to-temperature engine both at normal road speeds AND at idle – in the following conditions please: (1) A newly re-built engine (& oil pump), (2) A well-worn engine? (3) What is considered to be a minimum acceptable (hot) oil pressure - at idle?
Bruce. (PB0564)
Edited by - Bruce Sutherland on 28/03/2009 14:27:15
Bruce's question regarding oil pressure has pre-empted one I was just about to ask but for an N type engine. Will the answers also apply to a 6cyl? My oil pressure drops considerably when hot (typically after running for about half an hour). The oil pump gears look okay and the pressure release valve spring has been 'shimmed'. The engine was rebuilt about 10-12 years ago and has done some 17,000 miles since. At the moment I have 20/50 Millers Classic in but have recently bought a 40 monogade to see if that makes any difference. Any advice? Terry
I too was thinking about this very subject but in regard to M-type and J2 engines. Are the acceptable oil pressures the same for both engines in similar situations? The main difference (so far as I can see) in lubrication between a later M-type and a J2 engine is the diameter of the oil pipes. Is it possible to have better oil flow but at a lower pressure? And can higher pressure at times be a sign of restricted flow and not always necessarily a good thing ?
PB 0722 runs at 80psi normal road speeds and drops to 60psi on tick over. The engine was rebuilt about 5,000 miles ago with a new steel crank and rods with shell bearings and new oil pump gears (N-type). The centre main has been converted to shell bearings.
I use Castrol GTX 10/40 and change the oil and filter every 1000 miles. Unnecessarily frequent some might say, but considering what the rebuild cost I prefer a "belt and braces" approach.
An MGB overdive mated to the PB 'box (work done by Barrie Dean) gives me 7 forward speeds and the car just loves to bowl along in overdive top at just over 3000rpm.
John and Paul, Many thanks for your oil pressure figures, from which I conclude that if one were to contemplate fitting a low oil pressure warning system this should be set at 20 - 25 psig ('g' for ćgaugeĆ as apposed to ćabsoluteĆ).
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Posted - 26/03/2009 : 15:42:17
