low oil pressure warning

[Davidf]

Originally Posted by ard

With low oil pressure being one of the most devastating failures possible, I am surprised people suggest 'its just the sender'.

While that might be true 50, 60, 95% of the time, until it is definitively diagnosed do you risk a $20k motor with such a guess?

You can lose oil pressure without an oil leak.

Is there a reliable way an owner can assess this on the side of the road?

My suggestion is people should do what makes them comfortable if they get the low oil pressure warning light. For me, I played it safe and pulled over immediately. I first looked at oil level, it was fine. I then looked for leaking to ensure I did not dump the oil...no leaks. I then restarted the engine and listened. I was listening for valve noise. One of the first signs of no oil pressure would be collapsed lifters and thus valve "ticking". The engine sounded normal without any unusual noises. I then discovered that the warning would go out at 2500rpms or more. This told me that the oil pump sprocket had not come off the pump. So, on I went without trouble.

Simple to assume the worst and pay for towing would have been an option, but also a needless expense....especially knowing the pressure senders fail quit often.

[BMWjason]

Part # 11367539857....check valve caused low oil pressure warnings on earlier N62's. They would come apart and plug up the oil passages requiring replacement of the oil pump. Their are 6 check valves total, 3 in each cylinder head. They say this was remedied early on...maybe so, maybe no???

[bestvaluestore]

With the years some sensors just send false alarms but replace it if you wish.

[Boosted_s52]

I pulled over immediately once the light came on. Turns out it was my oil pressure sensor. You can check it from the side of the road. But if the car is hot it will be very challenging. Oil leaked through my oil pressure sensor into the plug. 15 minutes to change it out and haven't had a problem since.... I was very relived to see oil on my plug!

[ard]

Originally Posted by Boosted_s52

You can check it from the side of the road. !

How do you confirm a sensor fault on the side of the road?

[Davidf]

Yep, mine had evidence of the same type of failure. But, it is almost impossible to see the sensor without removing the vacuum pump...not sure how you would see, much less disconnect the electrical connector on the side of the road with the engine hot. Pulling the vacuum pump made the sensor replacement a sub-30 minute repair.

[Boosted_s52]

I had no problem doing mine without seeing it or removing anything else. I carry some microfiber towels in the trunk, wet one and put it over the vacuum pump to allow for a quick inspection. You can see the end of the plug from above. Reach you hand down and go from there. I used a deep 24mm socket and extension. Did the repair the next day.

[Davidf]

Usually, the electrical connector/socket will be full of oil. Sometimes the sensors leak oil and continue to work fine (oil leaks external to the electrical connector. Sometimes, the minor oil leak coincides with the sensor failure.

[Boosted_s52]

Originally Posted by Davidf

Usually, the electrical connector/socket will be full of oil. Sometimes the sensors leak oil and continue to work fine (oil leaks external to the electrical connector. Sometimes, the minor oil leak coincides with the sensor failure.

Correct, so on the side of the road I pulled the pressure sensor plug and noticed the oil inside of it. Could have been a lot of other things and it is risky to drive it without more diagnosis. I felt confident it was the sensor so I took the risk to drive it back home.