Hello all, i have a 2007 Cooper S with the N14 engine, has about 50k Miles on it. Vehicle originally came in with oil light coming on at idle.

Checked oil pressure: With engine cold oil pressure was perfect about 10psi at idle, about 45psi at 3k. When the motor would run for maybe 20 minutes getting to full temp, oil pressure would drop below 10psi and regardless of RPM pressure would not rise past 10psi.

Ive seen this before from oil filter housings failing.

First thing i did was replaced the oil pressure sender, did not help.

It did have an oil leak from the oil filter housing so a new housing assembly was installed. No fix

Read somewhere else that the oil pump chains go slack, dropped the pan, it did have a lot of slack and was hitting the engine case. Replace timing chain, guides, oil pump chain, and sprocket. No fix

Last resort, replaced oil pump. No fix

Removed the oil check valve below the vanos solenoid, valve was clean and seemed OK.

Removed the vanos solenoid, the screen was extremely plugged with sludge. removed screen and cleaned. No fix.

Absolutely going crazy with this one. Does anyone have any ideas?? anything would be worth a shot. Thanks, kyle

 

have you driven the car or you're still fixing it ever since you got?

 

Its a customers car, they just got it 2 months ago and the oil light would start coming on at idle. My last thought would be that is was run low on oil at some point and wore the main bearings a bit and when the oil gets to temp it starts to bleed past the bearing. Though the motor doesnt knock or anything.

 

if you remove the valve cover, do you see oil making its way up for the head?

also, try to pour oil across the head so the oil orifices are covered.

 

any codes?. I had chased down low oil pressure warning light flicker and found that with a gauge hooked up pressure would suddenly drop, at times to zero. then pop back up. Since the vanos valve solenoid feeds oil pressure through the camshaft to the cam sprocket actuator any leakage could contribute to low oil pressure. What I found was the camshaft sealing rings had worn deep groves into the bearing caps allowing pressure to bleed off when called for and coupled with a weak (leaky?)camshaft sprocket would cause the sudden pressure drop. Bearing caps are not available according to the dealer even thought the intake side looks as if they could be replaced . N14 have only the intake side vvt sprocket. I have the N12 which has vvt sprockets on intake and exhaust and since the exhaust side bottom bearing is machined into the head a new head is the only fix, too costly for my high mileage car. so far with just changing the camshaft sprockets I picked up 10 psi and no sudden drops Its a long shot I know.

 

No codes at all, thanks for your input. Thats interesting you found that with your cam bearings, was it a high mileage motor? I think ive narrowed this down to some sort of bearing issue, im going to pull the valve cover off and see if any of the cam caps are worn. Thanks!

 

Mileage is 178282. Car was purchased last year by my daughter at 169,000. Previous owner had done a lot of maintenance. It seemed to be well taken care of but within a thousand mile we had oil light flicker along with p00012 intake cam retarded. A new vanos solenoid and fresh oil change seemed to cure it only to have it return a few thousand miles later. Changed both again buying a better vanos solenoid seemed to be ok but problem returned again in a few thousand miles. I too was now thinking bearings.
What is troubling in your case is the consistent low oil pressure at speed when hot. given the fact that you've already changed the oil pump it sounds like bearings to me. Have you thought about having the oil tested? I Sent a sample to Blackstone labs they are reasonable and quick. Sample showed no signs of bearing material. Much easier than dropping the pan and removing bearing caps. If you do find groves in the cam bearing caps I think on the N14 engine the cam o rings are nylon based. ID card shows part number 11 31 7 587 757 as fitting 2007 s model minis might be worth changing. The ones for the N12 are metal much like a piston ring. One other thought I remember a thread where the dealer was able to check oil pressure in the lower engine against pressure in the upper engine there was a difference and the culprit in that thread was the oil filter housing I believe.