N54 low oil pressure

[jdconner19]

I’m new to this site and to the bmw brand so I’m not sure if this is the right place for this. With that being said, I did an oil change a couple weeks ago on my 07 335i and I now have a low oil pressure light. I scanned the car and the only code I’m getting is a bad oil level sensor. The light popped up after idling the car for about 30 minutes (it was pouring rain and I was waiting for it to let off before leaving work). I have checked and have no major oil leaks and the car was full of oil. I drained it and put fresh oil in just to be sure. I also put a new oil level sensor in the car. No metal shavings or signs of bad bearings in the motor. No lights popped up in the 2 weeks before letting it sit and idle the day I first saw the low oil pressure light. The light doesn’t pop up when the car is cold either. I had 5w-30 Castrol Edge in the car when the light came up. Only change is that the weather has been warmer, around 80*f the day the light came on. Should I use a higher weight oil for warm weather or am I looking at something a little more catastrophic?

[pbonsalb]

N54 are great motors but require a lot of sorting out at this age unless fantastically maintained. Most are not fantastically maintained. I had one for 10 years and still maintain it for the friend I gave it to.

I am having a hard time figuring out why you have low oil pressure after an oil change. How long have you owned the car? If this is your first oil change, do you know what oil was in it — weight and mileage? Maybe the PO had a problem and ran thicker oil to mask it.

What weight did you put in? I used 0W40 and 5W50. Given your oil light, I would go 5W40. What oil filter did you use? Was the one you removed for the oil change wrinkled and bent or were the pleats totally straight?

More catastrophic is possible, unfortunately. Bimmerworld recommends rod bearing replacement at 75k. I changed mine at 150k and they looked fair. I have not read much of oil pumps failing — I did a lot of preventative maintenance — rod bearings, turbos, turbo oil and coolant lines, water pump, thermostat, etc., but never the oil pump. I did install a crank guard plate behind the crank pulley and did buy a new oil filter housing — oil leaking on the front of the engine gets kn the belt and can ruin it. The result can be catastrophic if the belt breaks or frays and gets through the main seal.

[jdconner19]

I’ve owned the car for 3 months now. It has 170k miles. PO changed the oil not long before I bought it from him. He said he’s only ever used 5w-30 castrol in it, so that’s what I put back in it. The oil filter (I put in) was a little wrinkled when I took it out to check it and replace. I’ll try a little heavier oil. The PO didn’t drive the car often so he may not have noticed the lighter weight oil having an issue. I didn’t have any issues until the weather warmed up.

[M5Rick]

5w30? Just no. Its for run of the mill small shopping cars like Fords,VW's and Nissans.

[jdconner19]

I was told that is what bmw recommends for these cars. 5w-30 castrol and that’s all the PO said he put in the car. I will try 5w-40

[335i54n]

actually diagnose it, hook up a hf gauge (30). if bad, likely its had a belt sucked in and they never dropped the pan and cleaned the pickup.

[jdconner19]

I stuck a camera in the pan and looked at the oil pump screen and for any buildup in the motor when I took the level sensor out. The motor is clean.

[335i54n]

a gauge will tell you mechanical or electrical (uncommon) issue

[pbonsalb]

Based on what you write about inspecting inside the pan, 5W40 is worth a try, but an N54 in good condition won’t trigger the oil light at idle with 5W30.

You are sure the light is for oil pressure and not low oil? I think the yellow light with the oil can is for the level. It is not uncommon after changing oil to not immediately get an accurate reading. There may be a red light for oil pressure but I am not sure.

[jdconner19]

I changed the oil to 5w-40 and drove it home (about a 45 minute drive). So far the low oil pressure light on the idrive has not come back. I let it idle for about 5-10 minutes once I got home and all was good. I appreciate the help and suggestions.

[Leucosticte]

Check the oil pressure with a gauge and rule out the wiring/oil pressure switch. I've heard of rare instances where the switch itself fails.

[pbonsalb]

Originally Posted by jdconner19

I changed the oil to 5w-40 and drove it home (about a 45 minute drive). So far the low oil pressure light on the idrive has not come back. I let it idle for about 5-10 minutes once I got home and all was good. I appreciate the help and suggestions.

Fresh oil will thin out, so the light may come back on. I would call this a bandaid rather than a long term fix on a 17 year old N54 with 170k miles. I do recall my E36 M3 owners manual saying that the oil light may flicker at idle speed. The safest thing is, as others recommend, measuring oil pressure.

[whyzee125]

I would've suspected belt as well but if that's clean that's a good thing. While 5w40 may not show the same issue, that's not a true fix.

What oil filter did you use? Some aftermarket ones tend to scrunch up and may be due to not enough flow. Use the $7 Mann filters if you didn't already and see if that changes anything.

[jdconner19]

Well the oil changed did good for just a couple of days before the light came back. Finally got a gauge hooked up to it and once warmed up it’s showing about 5 psi of oil pressure at idle. Since the light came back I haven’t been driving the car, it was only run to do the oil pressure test. What can I expect price wise for doing an oil pump and rod bearings? ($120/hr) And is there anything else I should do with this stuff getting done? I still haven’t seen any metal shavings in the oil so I’m hoping everything else is good

[RockCrusher]

Originally Posted by jdconner19

Well the oil changed did good for just a couple of days before the light came back. Finally got a gauge hooked up to it and once warmed up it’s showing about 5 psi of oil pressure at idle. Since the light came back I haven’t been driving the car, it was only run to do the oil pressure test. What can I expect price wise for doing an oil pump and rod bearings? ($120/hr) And is there anything else I should do with this stuff getting done? I still haven’t seen any metal shavings in the oil so I’m hoping everything else is good

With that many miles on the engine an argument could be made the engine needs a total going over. Cylinders bored (just to clean them up), properly sized pistons/rings of course. New rod and main bearings.

Valve job. Refresh of the cam, cam drive, guides, tensioners, etc. and other valve hardware.

'course, new gaskets, seals, etc.

But that's expensive. And you have to have this done at a reliable shop. Ain't nothing cheap about a lousy engine rebuild...

Before tearing down the engine one might consider removing the oil pump and checking it for wear. A worn oil pump could account for low oil pressure. Also, any pressure relief springs need checking to make sure they are not bleeding away oil pressure. They don't get weak but a spring can fracture.

If the engine has oil jets for the pistons the oil pressure valve associated with this oil jet system needs to be looked at too.

If you find a smoking gun or two that accounts for low oil pressure you might not need go any further.

But if you do then rod bearings, but also main bearings, are on the short list. And of course the crank main and rod journals need to be checked to ensure they are not worn and just factory bearings can be used to restore the correct bearing clearances.

[pbonsalb]

Some possibilities to consider given the car history is unknown.

https://www.e90post.com/forums/showt...php?p=22812700

There are also N54 oil pump rebuild guides if you google.

[Rafichicago]

Just routine N54 maintenance. Good luck OP. Not for the faint of heart.

[pbonsalb]

At 150k miles with my N54 (in a 2008 E61 535xi), I changed the rod bearings and pan gasket but did not do anything to the pump. I owned the car from 30k so I knew the history. I also replaced the turbos and their oil and coolant lines, the water pump and thermostat and thermostat, the belt, some hoses, installed a crank guard, changed the filter housing gaskets, replaced the U shaped oil cooler hose, replaced the PCV valves, and more. I had gone the valve cover gasket previously. Also cleaned the vanos solenoids and replaced the wastegate reference hoses. And the trans pan and fluid, front and rear diff fluid, transfer case fluid, and motor mounts.

I think all that is fine for 150k miles. The car was 13 years old at the time. I spent a few days working on it and a couple of thousand dollars in parts. Car still drives great — I gave it to a friend and still maintain it.