I have a 2007 r52 Cooper S and I try to do my own maintenance. Mini and other Euro garages just charge way too much. Well they charge a decent price for the hell you have to go through to take this thing apart.
So after a frustrating week of wrenching for no reason I ran into a real issue upon closing up everything. My oil pressure is nominal upon cold however after putting the car under power (over 2k rpms), the pressure falls to zero. I just replaced the thermostat, water pump, timing chain and corresponding parts, and changed the oil on the super charger. Slap it all back together and all the issues I thought would be remedied were still present.
A little back story if it helps. When I bought the car it was perfect. The dealership had just replaced one of the abs sensors and assured me the clutch was brand new. Probably BS but I just wanted the car, I figured “What could possibly go wrong” or the famous “How bad could it really be?”. Fast forward 12k miles, I started getting this hellacious rattle. It wasn’t a heat shield and nothing was loose. I figured I would ask a Mini mech and possibly get a good answer.
$99 later I’m leaving the dealership pissed because they just told me the timing chain tensioner was failing and the guides are probably broken. Their quote was $2300. So I said screw it. Time to fix it myself.
I figured I would replace the hardest pieces at the same time and have a reliable car for once. Only the timing chain was actually “bad” so everything else was for peace of mind. Everything came off in a day and then the news hit. It wasn’t the timing chain. Everything still looked brand new. I replaced it anyways.
Fast forward 1 week and I take it out for a spin and red lights and everything I started with still exist. So I asked a Mini group on fb and by accident one of my problems was solved and also discovered a bad wheel speed sensor. The tensioner pulley stop had a rubber bushing missing, that was the noise. It only happened at idle with the a/c on or on a cold morning. That’s remedied and now this Oil Pressure trouble is the last issue(for now).
I tried disconnecting the coils and cycling the engine, no dice. I primed the pump prior to install and it just dribbled oil while I was installing it. I checked the oil pressure sensor and it had a little oil inside the plug I dried it out and nothing changed. What am I missing?

 

A broken drainback valve will cause low oil pressure at idle.

 

Are you measuring oil pressure with a gauge or just going off the idiot light on the dash? Pressure sensor failures are common.

 

I wish I had a gauge to find the oil pressure. I won’t be able to pick one up until next week. So yup it’s the light for now. I’ll order the sensor and replace it either way.
This drainback valve you mentioned. Is this under the valve cover?

 

It’s in the oil filter housing.

 

Ah, I got it. I’ll check it out and once I get the sensor replaced I’ll write back with my findings. Thank you for the replies!

 

you did not force the cover on did you? The oil pump is built into the timing chain cover, there's a couple of critical rubber seals there too

 

The timing chain cover went on pretty snug but I made sure the rings were in place before pressing it on. No brute force on anything German lol. I learned that lesson with my buddy’s GTI. The pump was also primed prior to install.

 

Try5/40 oil,,, older mileage engines need bit of help,,,,

 

Sorry for letting the thread lapse. I got the replacement oil pressure “switch” over the weekend and finally got it installed. There was moisture in the plug when I went to replace it. I sprayed and swabbed the plug, that solved the light problem. But I replaced the sensor afterwards since I was already back there. Thanks for the assistance everyone!