Hi everyone, I have a vexing problem with my low oil pressure light on my 2003 Mini Cooper S, and I'm at a loss for how to proceed. Many helpful folks on this forum have aided me in the past, and I again turn to you in my time of need. Thanks in advance for any assistance.

The low oil pressure light came on about a week ago. At first the light simply flickered at idle, but within a day it started to glow solidly all the time. I first checked the oil level, which was just fine. So I then opened up the oil filer housing to investigate, and found two problems: the oil filter was crushed and distorted inward, and the black oil bypass valve was loose with broken tips.

I'd read on NAM about the oil filter "cage" that some early Minis came with (although there seems to be some disagreement among the threads about whether R53s had this cage, or only R50s). Of course, if ever that cage were present, it was missing by the time I bought the car. However, I have also read that the later Mini oil filters with an internal plastic structure should work fine without the cage - and indeed they have for me over the last four years. This now-crushed filter (which had an internal structure) is the first unusual oil related problem I've encountered.

Also, because I'd read lots of helpful posts on this forum, I knew that the bypass valve was a common fault. Fortunately, I had a spare oil filter housing on hand, and was able to remove its intact bypass valve and install it into the housing on my car.

I hoped that installing the bypass valve and a new genuine Mini filter (with internal support structure) would solve the problem, but the oil light only went off for a few seconds after I started the car, and then came solidly back on. I drove the car around the block, and the light stayed on. So I took off the housing again, checked the new filter (which looked fine), re-seated the filter, and reassembled the oil filter housing. This didn't change anything, and the light is still on. I don't know what to do next.

I suppose it's possible that the oil pressure is actually fine and the sensor is in fact the problem. I checked the wire and connector, and they seem fine. I don't know how else to verify this theory except to buy a mechanical oil gauge and test it that way.

Should buying a mechanical oil gauge be my next move? If so, anyone have one to recommend?

Is there something else I should check? The car isn't making any unusual noises, but is it possible that the oil pump in the engine has failed?

 

 

Thanks for the reply, Tgriffithjr.

The engine has 260k, but has good compression and runs well. The oil is less than 1,000 miles old (Mobil 1 Full Synthetic 5w-30); so I didn't change the oil.

 

 

The oil pressure sender unit isn't expensive, so you might try that first, along with checking the engine ground strap.
But I think I'd get the real oil pressure checked by a mechanic with a mechanical gauge.
I can't find official specs but 3 or 4 psi seems awful low to me, for any engine.
I'd expect 10-20 psi at idle & 50-60 psi cruising - or thereabouts.

 

Oil pressure should be about 10psi for each 1000 rpm at a minimum. A little higher at idle. I would first try replacing the sender and while you are at it, check with a mechanical gauge. It is a matter of taking out the stock sender and installing the fitting for the oil pressure gauge. With that many miles, I would strongly suggest you check with a mechanical gauge. I have installed an electric oil pressure gauge in my MINI...just because...

 

 

Thanks for the thoughts.

I don't presume this car was treated particularly well. On the upside, it's completely stock, so I doubt anyone tracked or raced it. It's just that it has a ton of miles, and I have no reason to believe that it was well maintained.

I bought it as a parts car, to feed my original MCS. When I bought the car, it was very dirty, leaking many fluids, and had been sitting a while. Although it had a panoply of problems and more than 200,000 miles, the car turned out to be a decent driver after replacing the broken exhaust manifold. (It's amazing how poorly the car drove with a cracked CAT housing, and how well it drove after replacing the exhaust manifold. I've also corrected a bunch of other, smaller problems with the car - but that's a story for another thread.)

So yes, it's fair to assume that this engine is fairly worn. The unusual thing is that the oil light has not come on in the years I've owned the car, until now.

Thicker oil seems like a good idea. I may also swap out the oil pressure sensor (as I have one on hand in my spare oil filter housing). I'd like to get an oil pressure reading from a mechanical gauge, but I don't have a guage - and it would take some time to order one in.

If I do buy an oil pressure gauge, is the AutoMeter Ultra-Lite Analog 4323 the way to go?

 

Yes, try your spare sender just in case the existing one is faulty.
Yes, try a thicker oil - would it be smart to switch to non-synthetic 20/50? I don't know.
But yes, get the real pressure checked. Any local garage should be able to that easily - take a sender with you so that they can match the thread, but I think it's a standard taper.
As to the gauge I'll just comment that I'd look for one that has a 270 degree scale, max at 100 psi & the needle vertical at cruising altitude - hopefully around 50 psi. O'Reilly's have several & I assume they come with a few feet of tubing. There are others.

https://www.oreillyauto.com/detail/b.../4299447?pos=2

 

 

otfox wrote -

"of my oil pressure light going "off" at idle after an oil change? "

Don't you mean "on" ? That would indicate your problem of low or no pressure.

Mike

 

Hi Mike,

I think you may have commented on the wrong low oil thread. No one has posted on this thread in a couple years, and I don't see otfox's comment.

All that said, thanks for reminding me about the low oil problem on my Mini - that I actually never got to the bottom of. My MCS has unfortunately mostly sat idle due to this unresolved problem. Time to figure it out, and get back to motoring!

 

I added an oil pressure gage to mine. Just an FYI...the difference in pressure between cold (start up) and hot is large. Pressure might be 2x higher when it is cold.