low oil pressure
Turbo Mini Forums

hi all, my daily mpi has been lowering in oil pressure over the last few weeks when the oil is hot.

today it dropped to around 20psi on the gauge,with the warning light winking at me.

when driving/revving the oil pressure is fine, also idling when cold/warm (not hot)

i use the car daily,and plan to build a replacment engine for it over the coming weeks. i can then do a direct swap over a weekend keeping the car on the road. whilst im awating parts/block machining i need to keep the car going.

is there any way that i can raise the oil pressure when on idle ?

i am going to check the oil pressure relief valve. is it worth getting an adjustable version? can these alter the baseline oil pressure when oil is hot?

i also suspect that the oil pickup is smothered in parts - not helping with this problem

i realise it probably needs an overhaul, pump, bearings etc, also needs a new cam, and a bit of gearbox work, but need ideas to keep it going for a few more weeks.

anyone have any ideas?

cheers, dan

Change the oil???

You could put an adjuster on, but raising the oil pressure will probably just hide the underlying issue and potentially cause more damage.

That said it sounds ok to me, but if it is slowly getting worse then there is a problem somwhere.

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yes i realise that the bottom end is getting tired. as i said the cam needs replacing as a lobe has worn, new bearings, oil pump, overbore etc. so plan to build a fresh bottom end but i cant do that straight away and need the car daily. if i can maintain the oil pressure for now i can crack on and get an engine striped, machined, built for fitment in a few weeks time.

oil was new not too long ago, changed it maybe 8 weeks ago. might be worth a try changing that though, will also inspect the oil pressure relief, as well as ordering an adjustable oil pressure valuve and or packing the spring out a bit if i can.

low oil pressure at idle is not to do with the pressure regulator setting, so adjusting that will make no difference. If however, the regulator bullet is sticking or the seat is dirty, this could cause low idle oil pressure. Start here, remove the bullet and spring, clean it and ensure you clean the seat as well. You'll need to remove the starter motor to do this. In my opinion though, it is not your issue, since the regulator valve on the MPI is on the end of the oil gallery off #3 main bearing, so only ever sees 'clean' oil, if you have crap there, your crank and bearings are knackered as well!

The other likely cause is wear on the crank and bearings. This assumes a decent grade of oil has been used. either way, the MPi was specified with a 10W40 oil, so should maintain oil pressure, more so if you have used a 20W50 oil, but it might be worth trying new oil.

May I ask what oil you use?

thanks for the input. i will check the seating tomorrow and see how it looks. will also do an oil/filter change.

i have always used 10/40 oil (castrol GTX)

i have good cranks here, if the above dont work i am going to pull the engine, reshell the crank, new cam/followers/oil pump, clutch, also sort the crunch in the gearbox and drop it back in on my next weekend off.

Try a 20W50 first!

yeah thats sounds fine, 20/50 will deffo up it a bit at tickover

as the chaps state 20/50 and add 500ml of STP the gorilla snot addative in there

Cheers for the advice. I chenged the oil and filter. Had 10/40 here so went with that. The oil coming out didnt look great, i think it had started to break down. Also removed the bullet, replaced with a ball bearing and stronger spring. The bult had pitting/ marking to the seating part, one side also seems to be worn. Cold idle pressure is now 100 psi, as opposed to the 80 previous, warm idle around 25/30 psi . Will see how this goes over the weekend as i will be taking it for a fairly long run. May have to look at altering the spring height with the cold pressure, though it does warm up and drop fairly quickly

You really REALLY need to put 20w50 in there, its the correct oil for a mini, ignore instructions says 10w40, its too thin

went on a long run, oil got warm, tick over oil pressure is now 20-30 psi with hot oil. so back where it should be. oil pressure has gradually beenm getting lower since i built the engine around 30-40k ago, it just tailed off quickly over the last week or so. i think that the pressure relief was the main problem to be honnest

when cold the idle is 100psi ? is that not far to high of an oil pressure? is 20-30psi hot idle not right and i thought 60-70psi is about max as its just heating the oil and sapping power turning the pump over?

Cold idle pressure is now 100 psi, as opposed to the 80 previous, warm idle around 25/30 psi