Mi Dropping Oil Pressure T High Revs - Why?

[jez205 1]

As title, I rebuilt my Mi lump recently with new bearings (crank was measured as standard) oil pump and rings. I recently found the oil pressure was getting worse and found the cause to be collapsed oil cooler hoses, ive replaced these now which has improved things but when accelerating hard the oil pressure rises steadily until 5,000rpm where it rapidly drops down to the first mark on the gauge, the pressure warning light does not come on.

 

The engine is a 1.9 Mi on carbs, ive built a few of these and never had a problem in the past, its really winding me up as I cant get the most out of it!

 

The head was also rebuilt and still uses hydraulic lifters, these dont get noisey when the oil pressure drops so there must be plenty of oil in the head, the oil is fresh and up to the mark.

 

Any thoughts appreciated!

 

Jez

[whizzer71 0]

Poor connection/high resistance either in connector onto pressure sendor or multi connector over top of gearbox?,Or poss knackered spring in oil pump and or oil pump ??

 

[VisaGTi16v 1]

I had the scenario before where I had normal oil pressure whilst driving and even under light acceleration. When I gave it hard throttle however the pressure dropped off smoothly to naff all! Much debating later and speaking to other people at the sprint with no good ideas I just for the hell of it recrimped the plug on the oil pressure sensor cable......fixed.....! Slighty dodgy connection so current dropping off or whatever. Who knows. Not quite the same as yours but worth doing that sort of check as this was a year ago and its never done it since!

[Miles 331 1 Cars]

I'm going along the same line's of the pressure sender or the wire being faulty, Seen a couple of these like it now, Or if not worth checking your crankshaft pulley bolt is nice and tight as it's only fricton that holds it in place