22 replies to this topic

[Dusky]

More RPM should increase pressure regardless of bearing wear. I'm voting for an air leak.

[ACDodd]

Oil pressure does fall with rpm as the pump turned slower. Oil pressure for a road car should be 60 to 65psi at 3000rpm hot and 15psi idling.

Ac

Edited by ACDodd, 23 September 2019 - 07:31 AM.

[DEXISWOLF]

Oil pressure does fall with rpm as the pump turned slower. Oil pressure for a road car should be 60 to 65psi at 3000rpm hot and 15psi idling.

Ac

Mines doing the opposite great at idle but anything above 3500rpm its getting to 20 and will go lower

[DEXISWOLF]

Ive also checked and double checked when the engine came out again and changed all gaskets from pump to pickup and even filter housing and pipe too

[DEXISWOLF]

Check bearing clearances with plastigage or micrometers; what is the thrust bearing float clearance; have the cam shaft bearings being installed correctly and how is the clearance there. Are the oil gallery plugs in correctly - not leaking slightly. What oil are you using. There could be a problem with the pressure relief valve seat. What intake type are you using - there could be a restriction there. Hopefully you don't have blobs of silicon gasket sealer in the system.

I know i should have but i didn't check the endfloat or oil gallery plugs , the cam bearings was already installed , with it coming as a kit with all bearings included i thought that would have been checked back at jonspeed, i just installed everything thinking it was ok (i know stupid of me) but when i pull it again for the fourth time i think im going to check everything this time , im using a cheap 20/50 (for running in) ive used in loads of my previous minis and they have had great pressure, i also did try a better one too along with a few different filters ,

[MiniMadRacer]

I had a similar issue years ago on a 1275 GT A Series lump which had a hairline crack in the brass oil pressure switch / oil pressure gauge T piece. replaced that and all was good. I only found it when I decided to "plug" in a different oil pressure gauge under the bonnet and unscrewing the connector the brass T piece came out with it

[DEXISWOLF]

I might look at that t piece later , cheers for that

[carbon]

More RPM should increase pressure regardless of bearing wear. I'm voting for an air leak.

My experience was that with worn big-end shells the oil pressure dropped off from about 1500-2500 rpm with the engine warmed up. And then above 2500rpm started to increase again.

 

And how do I know it was the big-end shells? Because these were worn down to the copper. The crank was OK, this being one of the few benefits of a nitrided crank...

 

The big end shells were replaced, and normal oil pressure was restored.

 

Could be an air leak, but I would suggest first checking all the mains and big-end bearing clearances with Plastigage.