Oil light comes on while idle

Wen I drive my car after lik 10mins the oil light starts to come on after I come off the clutch or idle. I just got the rear main seal replace but tht didn't work either

You need to give more info. How much oil are you loosing per day. Do you have smoke out of the exhaust? Have you had the oil pump checked out?

Yes, much more info. I hope you didn't replace the rear main to cure an oil light issue... completely unrelated.

Your idle speed is probably dropping too low at idle, I would check that spec and adjust first.

It has a leak .... I don't drive it cause of the problem...say I come to a red light wen ever I put the car in neutral the oil light blinks the more I drive the car the light jumps on in neutral

The rear main seal was leaking that's why I replace it

1) Find and fix the oil leak

2) Make sure oil level is correct

3) Make sure idle speed is set correctly and the idle control valve is clean and functioning to maintain steady idle.

If the light still flickers after you do the above, then we have some more troubleshooting to do. I suspect this will cure it though.

Ok so far I've change the oil pan gasket I've change the rear main seal it could be the valve cover gasket cause wen the oil gets hot the car starts to smoke a little on the side where the valve and spark plugs are under the hood

Originally Posted by 525iclassicguy

Ok so far I've change the oil pan gasket I've change the rear main seal it could be the valve cover gasket cause wen the oil gets hot the car starts to smoke a little on the side where the valve and spark plugs are under the hood

Agreed regarding leakage and smoke.

However, it does not address your oil light issue. Everything snowsled7 has told you is spot on.

What is your tachometer indicating (in rpm) at idle when the oil light is coming on?

I can't really get in to detail but im going to tell you exactly wats going on ........say I take a ride at first everything seems good no issues. But when the oil start to flow and the car warms up as I'm driving first gear, second gear, third gear, then I'm come to a red light wen I take the car out of gear and switch it to neutral the car idles ruff and vibrates the low on oil light blinks as if the car is low on oil but its not the longer you drive the car the worst the idle get when you take it out of gear then it's starts to shut off wen in neutral after a while so I pop the hood to see wats going on and light smoke is coming for the side where the valve, spark plugs, oil filter etc are located and the car is leaking oil after I did the replacements....????the car went from overheating to this issue

If this is the E28 with M20 motor replace oil pressure switch is probably soak with oil, is cheap and easy to do

E34 but yeah same M20 tho

Originally Posted by 525iclassicguy

I can't really get in to detail but im going to tell you exactly wats going on ........say I take a ride at first everything seems good no issues. But when the oil start to flow and the car warms up as I'm driving first gear, second gear, third gear, then I'm come to a red light wen I take the car out of gear and switch it to neutral the car idles ruff and vibrates the low on oil light blinks as if the car is low on oil but its not the longer you drive the car the worst the idle get when you take it out of gear then it's starts to shut off wen in neutral after a while so I pop the hood to see wats going on and light smoke is coming for the side where the valve, spark plugs, oil filter etc are located and the car is leaking oil after I did the replacements....????the car went from overheating to this issue

It seems that your oil light is directly related to your poor idle. It sounds like your engine RPM are getting so low that it loses sufficient oil pressure thus triggering the oil light.

Have you investigated the possibility of a bad O2 sensor? If it is fine when cold, then the problem starts when it is warmed up, then the O2 sensor may be bad. It should be throwong a code if that is the case. I'd recommend you do the stomp test to see if there are any codes stored in the DME and address them if there are.

Good luck.

I haven't had this issue with my BMWs, but I had the exact same symptoms on a 93 Range Rover I used to drive. In my case, it was the main bearings on the crank. When the oil was cold, the oil pressure was above the sensor specs, but as it heated, the worn bearings could no longer maintain back pressure thru the journals in the crank. The engine had no knocks or noises to indicate worn mains.

Originally Posted by CurtSmall

I haven't had this issue with my BMWs, but I had the exact same symptoms on a 93 Range Rover I used to drive. In my case, it was the main bearings on the crank. When the oil was cold, the oil pressure was above the sensor specs, but as it heated, the worn bearings could no longer maintain back pressure thru the journals in the crank. The engine had no knocks or noises to indicate worn mains.

Certainly a possibility, but let's hope not for OP

Originally Posted by CurtSmall

I haven't had this issue with my BMWs, but I had the exact same symptoms on a 93 Range Rover I used to drive. In my case, it was the main bearings on the crank. When the oil was cold, the oil pressure was above the sensor specs, but as it heated, the worn bearings could no longer maintain back pressure thru the journals in the crank. The engine had no knocks or noises to indicate worn mains.

Right but, that is on a Buick engine designed in the late forties.

To the OP...

This is really simple, the answer has been given and confirmed. Oil is thicker when cold, that is why it gets progressively worse. It takes almost 30 minutes of driving to fully warm your oil, especially in the winter. When the idle speed drops, the pressure warning light flickers because the pressure IS dropping. There is nothing wrong internally, there is a problem with getting the car to idle at the proper speed.

Fix the idle, fix the oil light.

So, clean and test the idle control valve, you can do this at home for free. Replace if necessary.

As mentioned the O2 sensor is a possibility for your rough running but I doubt it. Spark plugs, valve adjustment if applicable are some other cheap things to check.

So fix the leaks and get it running right, stop worrying about the oil light, it is a symptom, not the problem.

I know it's not the oil light I never said it was.... All I said was it blinks wen idle. I'm gettin the oil pressure switch tomorrow and I go from there .....

Originally Posted by 525iclassicguy

I know it's not the oil light I never said it was.... All I said was it blinks wen idle. I'm gettin the oil pressure switch tomorrow and I go from there .....

There is nothing wrong with the oil pressure switch. I'll bet you the problem remains...

+1 on fix idle speed. From info given that seems the major problem. I doubt it is the pressure switch.

If you have no further leaks, and you are not losing oil (check the dipstick regularly of course, around 5 minutes after total engine/elecctrical shutdown, and on a level road), and if you don't have an oil pump code, then its either a defective oil pressure indicator or a too poor idle as you've been suggested to.

The idle speed can be adjusted easily by turning the screw thread on the idle control cable that is connected to the throttle. Not a good description but if you look at it you'll immediately understand what I mean. As you turn it clockwise and counter clockwise (to tighten and loosen which increases and reduces your idle speed accordingly), you can actually see the cable move and pull the throttle open or release it etc.

And there I was fixing things like idle control valves/motors; unblocking throttle body drillings; checking for vacuum leaks all over when all I had to do was tighten the throttle cable! What a fool I have been! Don't like your fix RB - sorry. I think you are adjusting the auto box kick-down cable any way!

The ECU will do all it can to keep the idle at its preset levels in all conditions (hot/cold/air con on-off/park or in gear) all we as maintenance persons do is fix broken bits so the ECU can do its job. Tightening cables does not cut it at all. 7 - 8- 9 out.

Originally Posted by robertobaggio20

and if you don't have an oil pump code,

An oil pump code

The oil pump doesn't throw codes bobby, between this and the cable adjustment you might want to reconsider posting in help threads until you understand what you are talking about.

Roberto, the set screw is not the correct way to adjust the idle on the M20. that screw is only designed as a stop so the pressure of the butterfly valve is on that and not the disk inside preventing the high tension springs from closing.

the correct way is to clean or replace the idle control valve. it couldnt be any more black and white.

please dont post if you dont know what you are talking about. certainly no oil pump code on an M20 engine either. infact hardly any codes at all

The problem was a piece of the head gasket was bad so until I get the head gasket replace I used some of that liquid head gasket seal and everything works fine now til I get the head job done

Originally Posted by 525iclassicguy

The problem was a piece of the head gasket was bad so until I get the head gasket replace I used some of that liquid head gasket seal and everything works fine now til I get the head job done

Sorry to hear it is a HG. How did you come to that conclusion?

My mechanic put on the lift and seen it leaking a little bit from heads right under the spark plugs