Low oil pressure

[Cintas]

As I am sure it is known to all that I recently changed my headgasket due to a timing belt snapping. I have replaced the valves had the heard resurfaced and got the car running. I can leave it idling for 20’mins no problem but after I take it around my apartment the oil like starts to flicker and the the low pressure warning comes on. It will sometimes come on as soon as I put the car in reverse or drive. I have never had an issue with this prior the timing belt breaking and am at wits end with this engine. I just need to to get it up and running so any help would be appreciative. Thanks.

It’s a m20 motor on an e34

[bimmer@15]

If its intermittent could it be the sensor itself?

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[south42]

What oil are you using? and yes the sensors also go bad.


Andy

[Cintas]

I am running 20w50 I replaced the sensor when the timing belt issue happened. When the car shut off mid drive I got a low pressure warning so replaced it first but I’ll double check it again

[Singing6]

STOP. Put an oil pressure gauge on the engine and crank it with the fuel pump fuse (#23 iirc) pulled. it should make oil pressure and hold it pretty steady. If it does not, you obviously have a big problem. Good luck and godspeed.

[south42]

I had 528e and had to replace the main bearing at 290,000 miles, was able to do it wih the engine in the car.


Andy

[Cintas]

I’ll see if I can get a gauge from autozone and try that tomorrow

- - - Updated - - -

I had 528e and had to replace the main bearing at 290,000 miles, was able to do it wih the engine in the car.




Andy

Well mine only has 118000 so hopefully that isn’t the case

[Cintas]

So update

I replaced the oil pressure switch and drove it around the complex no light but the oil light slight flickered when I slowed down or cam to a rest while in drive. Just as I was pulling in the parking spot the car died.

[bimmer@15]

It died, of seized?

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[Cintas]

It died, of seized?

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No it cuts off like a stalling engine. It stars right back up.

[bimmer@15]

Fuel filter/ pump?

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[Cintas]

Shouldn’t be those were replaced a year ago. I have started and ran the car for 20 minutes before driving. It only dies as it slows down like when I am about to park.

[bimmer@15]

Icv or vacume leaks?

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[Cintas]

Icv or vacume leaks?

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Though about vacuum leaks didn’t see any cracks and haven’t checked the icv. How would I go about checking that?

[bimmer@15]

Take it out and if its stiff or has carbon in it spray it with brake cleen untill you can shake it and hear the valve knocking around

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[Cintas]

So another update, let the car run for 45 mins and about 40 minutes in the light starts to flicker. I took the oil cap off and the car ran just fine with no oil pressure warning. Any idea what would cause this?

[bimmer@15]

Possibly a clogged pcv?

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[moroza]

Smoke tests are the best way to find intake leaks.

STOP. Put an oil pressure gauge on the engine

This. We need numbers in units of pressure (bar, kPa, psi... dram furlongs per fortnight squared per oxgang... )

[Cintas]

Possibly a clogged pcv?


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From my understanding the m20 motors don’t have a pcv right?

[ross1]

What is your idle speed?
An engine idling too low, especially a tired one, will have very low oil pressure as the pump is barely turning and the oil is escaping (wide when worn) bearing clearances faster than the pump can move oil.
If you are having stalling problems address that first before assuming oiling problems.
Just did a head gasket? Check your work, look for vacuum leaks.

[Singing6]

Smoke tests are the best way to find intake leaks.



This. We need numbers in units of pressure (bar, kPa, psi... dram furlongs per fortnight squared per oxgang... )

I know the M50 is 7-28 psi at idle. Don’t know m20 off the top of my head. Also too lazy to convert this to kN/um at the moment.


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[ross1]

Pretty sure the warning light switch threshold is .5 bar, a bit over 7 PSI.
If OP's light is coming on just before stalling it seems a moot point for now.

[Cintas]

What is your idle speed?
An engine idling too low, especially a tired one, will have very low oil pressure as the pump is barely turning and the oil is escaping (wide when worn) bearing clearances faster than the pump can move oil.
If you are having stalling problems address that first before assuming oiling problems.
Just did a head gasket? Check your work, look for vacuum leaks.

So vacuum leak could be causing the stalling and would be separate from the oil pressure issues? Also the car runs better and doesn’t give the pressure warning once the oil cap is off. I have been traveling for work and won’t get a chance to look at till this week. I’ll report back when I do.

[ross1]

You haven't stated the idle speed. My suspicion(from here)is that given stalling you may be idling too slow. I explained in previous post.