Low engine oil pressure 535i

[yaofeng]

If it is not a bad sensor, the damage would have already been done. There is too much pressure drop to trigger the sensor to give you an indication on the instrment panel.

[hlenoble]

I have a '90 535i with just under 160K miles. I garage the car over the winter, and today was only about the 3rd time I had it out this year. I drove about 80 miles to work with no issues, but coming home after getting off the highway I got a low engine oil pressure warning on the message center.

The oil pressure light flickered, but did not stay on. I got the message again a few minutes later. I am concerned and I have a few questions:

Is this likely just the engine showing signs of wear? If so, I would likely change the oil and use 10w-40 instead of the current 10w-30. Thoughts?

Is it more likely to be a bad oil pump? If so, is it replaceable like the one in my old e30 325e or essentially not replaceable like in my lousy old mini van from years ago?

Finally, is there anything else I should consider?

Thanks...

[bad_manners_god]

I would think it's more of a faulty sensor.

The only time I got this messege was after I shattered my oil-pan on a really bad pot-hole and saw all the oil in a trail in my rear-view and turned off the car immediately.

[Ken35i]

If you had low oil pressure, you would hear the 'clacking' that the rockers are making by running over the cam lobes alot louder (even inside the car). Just experience I've had with other cars.

But the oil pressure light flashing on and off? Wouldn't think the pressure would jump up and down like that unless right on the threshold of the sensors limit. Educated guess...

The oil pump is replaceable...you just need to take the engine out, other than that it just bolt off bolt on.

Best of luck, hope its just a faultly sensor. ;)

[Ross]

Your engine is notorious for loosening "banjo" bolts that retain the oil lines to lubricate the rockers. This could account for low pressure.
A faulty sensor or low oil level is also a possibility. check the level if you haven't and either replace the sensor or verify it's accuracy with a known good gauge.
I didn't notice your location but 10-30 oil is also a bit too light for the M30 engine, they like 20-50 above 40*f.
Worn bearings or pump can cause your symtoms but if the engine has otherwise been healthy and reasonably well maintained it's not likely. The bottom end of your engine is very durable.

[Derek A.]

You should put a mechanical oil pressure gauge on the engine and see what kind of pressure it is making. It will confirm no mechanical problems. If you are due for a valve adjustment - its a good time to pull the valve cover off, adjust valves and check the banjo bolts. Even if you just pull the cover to check the banjo bolts its only a 15 minute job.

[Derek A.]

When I did VDO gauges on my e28 m30. The BMW unit that retained the idiot light called for a 150 psi gauge and sender. Cold with 20w50 I was getting 80-90 psi.

[hlenoble]

I changed the oil when I got home from work, with 10W-40 this time. I'll take it to work tomorrow and see what happens.

Thanks for the help, and I'll keep you informed.

[bmwpower]

Your engine is notorious for loosening "banjo" bolts that retain the oil lines to lubricate the rockers. This could account for low pressure.
A faulty sensor or low oil level is also a possibility. check the level if you haven't and either replace the sensor or verify it's accuracy with a known good gauge.
I didn't notice your location but 10-30 oil is also a bit too light for the M30 engine, they like 20-50 above 40*f.
Worn bearings or pump can cause your symtoms but if the engine has otherwise been healthy and reasonably well maintained it's not likely. The bottom end of your engine is very durable.

20w-50? Really? I use 10w-40, but maybe my pressure is lower than is should be.

[bad_manners_god]

Very nice V1 setup, looks pretty good.....It seems far from your direct line of sight though?

Where have you hard-wired it.

I only use a Cobra XRS-9930, mounted it near my rear-view mirror. But I have a LPP Laser Jammer molded into the bumper impact stripes.

[Ferret]

Your engine is notorious for loosening "banjo" bolts that retain the oil lines to lubricate the rockers. This could account for low pressure.
A faulty sensor or low oil level is also a possibility. check the level if you haven't and either replace the sensor or verify it's accuracy with a known good gauge.

This is my first thought - my 525i used to have a paddy when it's oil got to about the 50% mark - fling it around a corner or brake hard and the oil pressure light would come on complete with a *bong* warning about 3 seconds later.

It didnt have long left in this world when it started doing it, so I never bothered hunting down the cause - however I suspect it may be air getting into the pump that causes the sudden flickering, combined with an old pressure sensor! I should really get some guages set up on mine...

[bmwpower]

Very nice V1 setup, looks pretty good.....It seems far from your direct line of sight though?

Where have you hard-wired it.

I only use a Cobra XRS-9930, mounted it near my rear-view mirror. But I have a LPP Laser Jammer molded into the bumper impact stripes.

Thanks!...V1 is hardwired and hangs just under the rear view mirror.

I haven't found it to be a problem being where it is. I thought about putting it in the rear fog bezel, but that location is a little hard to see with the steering wheel in the way.