Low oil pressure light when idling [M43B19TU]

[Jawn46]

Ive been having this problem for months already, when the engine is cold i dont get the red oil lamp but when the engine is hot i always get it when i am idling stop shield/traffic lights etc.

If i tap the gas a little bit ~1200 rpms it goes away.
Ive changed the oil and filter (10W-40), changed the oil pressure switch, replacing oil filter housing gasket (was leaking a little bit).
Engine oil is topped off.

I have not checked the oil pressure or the oil pump, i wanted to know if there is something else i can do myself before i take it to a shop.

[MarcoZandrini]

How many kilometers/miles on the engine? What’s the engine’s maintenance history? What brand of oil are you putting in the engine? What brand is the new oil pressure switch?

[Jawn46]

How many kilometers/miles on the engine? What’s the engine’s maintenance history? What brand of oil are you putting in the engine? What brand is the new oil pressure switch?

It has 319K km on it.
I used Castrol oil.
The oil pressure switch was by Febi Bilstein.
have had the car for one year now and i don't drive much but i can tell you what has been done on the car since i have it.

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[MarcoZandrini]

That’s an impressive list of things replaced. The oil pressure switch is likely ok as FEBI Bilstein makes quality parts. The ideal thing would be to screw an oil pressure gauge into the oil pressure switch port. It could be the engine needs a rebuild.

[E39 Newbie]

Ive been having this problem for months already, when the engine is cold i dont get the red oil lamp but when the engine is hot i always get it when i am idling stop shield/traffic lights etc.

If i tap the gas a little bit ~1200 rpms it goes away.
Ive changed the oil and filter (10W-40), changed the oil pressure switch, replacing oil filter housing gasket (was leaking a little bit).
Engine oil is topped off.

I have not checked the oil pressure or the oil pump, i wanted to know if there is something else i can do myself before i take it to a shop.

This is typical behavior of a high-mileage engine with worn bearings. I bought a high-mileage Ford project car some years ago with the exact same problem. When the oil is thicker, during cold start-up, there is more oil pressure. As it comes to temperature and thins out the oil pressure drops. Revving the engine a bit causes causes the pressure to pick up enough to turn the warning light off.

As a crutch you can use a much higher viscosity oil, maybe 10w-60, and see if the problem improves. It's not a solution, it just keeps you driving for a few more months or years, depending on how much you drive. But the ultimate solution is a new set of bearings. Not terribly difficult if you can DIY, but really expensive if you have to pay a shop to do it.

[Jawn46]

To replace the bearing i would need to take apart the whole engine right?
I dont have an engine hoist or engine stand, so that would be a bit difficult.


Can you also tell me why you think it might be worn bearings, couldnt it be something with the oil pump?
thanks for the help btw

[E39 Newbie]

To replace the bearing i would need to take apart the whole engine right?
I dont have an engine hoist or engine stand, so that would be a bit difficult.


Can you also tell me why you think it might be worn bearings, couldnt it be something with the oil pump?
thanks for the help btw

The rod bearings can probably be done in situ, but the crank bearings might be too fiddly. Sure it would be easier to have the engine on a stand.

I'm not familiar with your engine. I know the pumps in the M54 and M52 are pretty rugged. I can't speak for the M43. But in my experience low oil pressure in a high-mileage engine is very often worn bearings. I think a malfunctioning pump would exhibit pressure problems all over the RPM range, not just at idle.

[MarcoZandrini]

I’d get a mechanical oil pressure gauge and screw it into the port when the oil pressure switch is located. The oil pressure switch is typically triggers the low oil pressure light at 7psi and below. If the oil pressure is low I recommend you switch to a higher viscosity oil.

[Jawn46]

The rod bearings can probably be done in situ, but the crank bearings might be too fiddly. Sure it would be easier to have the engine on a stand.I'm not familiar with your engine. I know the pumps in the M54 and M52 are pretty rugged. I can't speak for the M43. But in my experience low oil pressure in a high-mileage engine is very often worn bearings. I think a malfunctioning pump would exhibit pressure problems all over the RPM range, not just at idle.

Would it be enough to replace the rod bearings and leave the main bearings as they are?I read that the rod bearings are the ones that can cause low oil pressure.

[E39 Newbie]

Would it be enough to replace the rod bearings and leave the main bearings as they are?I read that the rod bearings are the ones that can cause low oil pressure.

Broadly speaking, the rod bearings take more of a beating than the mains, simply by virtue of the up and down forces from the rod. But much depends on how the previous owner(s) treated it. It certainly can't hurt and would be a good place to start.

I think as Marco advised above, first get a known good mechanical pressure gauge and verify that you do, indeed, have low oil pressure. You don't want to spend a ton of money and find out it was something simple like a bad sensor all along.

[Jawn46]

Broadly speaking, the rod bearings take more of a beating than the mains, simply by virtue of the up and down forces from the rod. But much depends on how the previous owner(s) treated it. It certainly can't hurt and would be a good place to start.I think as Marco advised above, first get a known good mechanical pressure gauge and verify that you do, indeed, have low oil pressure. You don't want to spend a ton of money and find out it was something simple like a bad sensor all along.

https://bimmercat.com/bmw/en/search/fg/11_2058.jpg?v=01.2020

In this diagram, i would be just replacing 6 and 7 right?I will order the parts today or tomorrow

[dworthy]

+1 Get the pressure tested first before throwing bearings at it.

Something else that affects the oil pressure is the 2 small O-Rings at the bottom of the oil filter cap. Most kits come with just the large O-Ring, and when aged, the smaller ones can cause low pressure off idle. Also you shouldn't be using 10W-40, for that will impact the hydraulic lifters, use a 5W-30 or 0W-40.

[Jawn46]

+1 Get the pressure tested first before throwing bearings at it.

Something else that affects the oil pressure is the 2 small O-Rings at the bottom of the oil filter cap. Most kits come with just the large O-Ring, and when aged, the smaller ones can cause low pressure off idle. Also you shouldn't be using 10W-40, for that will impact the hydraulic lifters, use a 5W-30 or 0W-40.

I will order an oil pressure gauge today first thing then.

But if the red oil lamp only appears when the engine is hot (around 30min. of driving), wouldnt that mean the sensor is fine and it actually is low oil pressure? Because the viscosity of oil has dropped.

[E39 Newbie]

I will order an oil pressure gauge today first thing then.

But if the red oil lamp only appears when the engine is hot (around 30min. of driving), wouldnt that mean the sensor is fine and it actually is low oil pressure? Because the viscosity of oil has dropped.

Generally speaking, you're correct. But you'll need accurate pressure readings just to verify.

Another test is to fill with a higher viscosity oil, maybe 20W-50 or 10W-60. If your pressure issue gets better then you can assume worn bearings. This is a common crutch used on older cars with bearing wear. You can squeeze some more time from a tired engine.

[E39 Newbie]

https://bimmercat.com/bmw/en/search/fg/11_2058.jpg?v=01.2020

In this diagram, i would be just replacing 6 and 7 right?I will order the parts today or tomorrow

Correct. Does that engine use bolts or studs on the rod? If bolts, they are probably TTY bolts so you'll need a set of bolts.

While you're in there, pull one of the main caps. Check the condition of the bearing. if it's worn the others will be, too, and it's time for more extensive work. These, too, are probably TTY so you'll need new main bolts.

[Jawn46]

I tested the oil pressure of the car when cold and when hot (20-30min. driving, thats when the red oil lamp starts flickering).
When i started the car the oil pressure was 58 psi (idle).
After 30min. of driving the oil pressure was at 9 - 9.5 psi.
My car idles at 900 RPM btw.





Rod: https://bimmercat.com/bmw/en/search/...43/ECE/11_2010
Main bearing cap bolt part number: 11-11-1-735-525

So both bearing use bolts and i dont have to replace them right?

I would order the parts today to change the rod bearings and i also have a few of other small things i need to order.
Cause 9 psi at 900 rpm is like the bare minimum right cause the oil switch does always flicker and also i have to consider i am using a thicker oil than is recommended for this car. (10W-40 instead of 5W-30).

[E39 Newbie]

58 to 9 is quite a drop. I will not be surprised if you have more problems than just worn rod bearings.

The rod bolts AND the main bearing bolts are torque-to-yield. You will need to replace them all.

Before you go to all this trouble, if you're going to open the bottom end buy some PlastGauge. Amazon has it. Pull one of the main caps and check the bearing. IF the bearing looks normal cut a piece of the correct Plastigauge off, stick it on the crank, reinstall the cap and torque to specs. Then unbolt it and measure the width with the little sleeve that it comes in. Check the clearance against the factory specs. If it's out of spec then they are ALL out of spec and you are looking at having to pull the engine. I suspect you're going to see bearing damage before you get this far.

If all is OK, proceed with the rod bearings.

[Jawn46]

58 to 9 is quite a drop. I will not be surprised if you have more problems than just worn rod bearings.

The rod bolts AND the main bearing bolts are torque-to-yield. You will need to replace them all.

Before you go to all this trouble, if you're going to open the bottom end buy some PlastGauge. Amazon has it. Pull one of the main caps and check the bearing. IF the bearing looks normal cut a piece of the correct Plastigauge off, stick it on the crank, reinstall the cap and torque to specs. Then unbolt it and measure the width with the little sleeve that it comes in. Check the clearance against the factory specs. If it's out of spec then they are ALL out of spec and you are looking at having to pull the engine. I suspect you're going to see bearing damage before you get this far.

If all is OK, proceed with the rod bearings.

I measured today again.

I think its 46 psi right when i start it and 9-10 psi when its hot.
I ordered the parts already, so i will just change the rod bearings and hope it fixes it somewhat
Doesnt have to be ideal but a bit more oil pressure would be fine.

[E39 Newbie]

Be sure to post pix of the upper and lower shells.

[Jawn46]

I finally got all the parts now and when trying to start to take the oil pan off i realized its completely blocked by the subframe, so research shows me i have to take off the subframe to access the oil pan and thats a lot of work which i really dont mind but i need to lift the engine a bit, i would need to buy something like a engine support bar unless i can find some cheaper alternative.

[MarcoZandrini]

I think those oil pressure numbers are ok. As I remember the red oil pressure light is supposed to come in when pressure gets below 7.5psi. I’d definitely go for a fully synthetic 0W40.

[cnn]

Why don't you use 15W50 oil and done with?

Did the check the oil filter cap for the 2 small O-rings (green color)?
After some 20 yrs, best is to get a new oil filter cap.

Also, the OFH one-way valve may be defective.

Most of the time the red light at idle is harmless, assuming you already checked the oil pressure as above.

No need to replace the rod bearing, which is a HUGE job and not needed!

[Jawn46]

Just finished replacing the rod bearings and the bearings i had looked really good already. Didnt change anything about my low oil pressure though. Didnt have to replace them but now i know atleast. Talked to a mechanic today and he told me it will be most likely the oil pump and that there are 2 passages i will probably have to clean to have decent oil pressure again, so i am gonna try to find a guide on how to take the oil pump apart.

[captan330]

Çubuk yataklarını değiştirmeyi yeni bitirdim ve daha önce sahip olduğum yataklar gerçekten iyi görünüyordu. Düşük yağ basıncımla ilgili hiçbir şey değişmedi. Onları değiştirmek zorunda değildim ama şimdi en azından biliyorum. Bugün bir tamirciyle konuştum ve bana büyük olasılıkla yağ pompası olacağını ve tekrar düzgün yağ basıncına sahip olmak için muhtemelen temizlemem gereken 2 geçit olduğunu söyledi, bu yüzden nasıl alınacağına dair bir rehber bulmaya çalışacağım. yağ pompası ayrı.

did you solve this problem? same problem happened to me. I'm going to replace the oil cap gasket and valve this weekend and have a look.

[captan330]

did you solve this problem?