[AbbeyRoad]

Post 1:

This is a continuation of the thread: https://f30.bimmerpost.com/forums/sh....php?t=1840066

So the backstory is I got this X5 on auction in April 2024 and did all the maintenance on the Engine, spending about $8k on parts: I did,

1. Cam seals
2. Valve seals
3. Most sensors and solenoids
4. Front main seal and timing chain
5. Bunch of plastic bits and trim in the engine and all over the car, and many electrical problems, including restoring the front passenger and driver interior door cards.
6. Valve cover
7. Rebuilt the turbo
8. Water pump and pipes
9. Some suspension parts

This all took over two months to complete in my driveway. I did NOT remove the oil pan.

And then I had the car checked out at a BMW specialist and they said I had done an awesome job. Then I drove the car, clocking about 3,000 miles.

All good.

[AbbeyRoad]

Post 2:

So on November 2, my engine locked up on the highway.

The starter could turn over maybe 1 turn. But it was otherwise seized.

3 rod bearings had spun. There were no engine codes.

[AbbeyRoad]

Post 3:

The oil starvation and rod failure problems with the N55 seem to have two causes. The first is hard turns on the track, and this is fixed using: the S55 secondary oil pump; and/or oil pan baffle system; and/or overfilling oil.

The second cause is unknown and is fixed by: computer remap to raise oil pressure; and/or harder aftermarket bearing shells; and/or replacing various components like the oil pickup; and/or special oil or oil replacement schedules.

Here is my own discovery that the N55 variable rate oil pump can never work properly long-term IMO. My plan is to drill a strategic hole in the pump and to flip the piston in the video, to block the variable rate mechanism of the pump.

Videos,

Part 1:

Part 2:

[AbbeyRoad]

Post 4:

[LA1Z24]

The DME will throw codes if the oil pump does not increase output when commanded. So if you plan to hard modify the pump, you're also going to have to custom code the DME to understand what you've done to the pump

[ThicF30]

There is super good info here. I’m curious to try the oil pump piston swap. In regards to the DME I believe you can ignore codes thrown using bootmod3 not sure if this would work? I have also spun bearings twice on n55, currently building 2nd engine with all new components. For back ground,
The car was low on oil first spun bearing and stock sensor never notified me of low level. Second time car was redlined for an unknown amount of time as my wife decided it didn’t need to be shifted from first gear 🤣. Both situations were obviously out of the ordinary however while everything is easily accessible I’d like to assure it never occurs again.

[Ilvez]

As I wrote before - I do not believe that root cause of your current engine failure is a systematic issue related to N55 oil pump design. There are millions of N55 engines out there and seizing up during steady driving is clearly very exceptional event. Harder crankshaft shells are definitely not a solution for avoiding potential damage as shells are not in contact with crank. Replaced N55 shells need to be matched with individual tolerance markings on the crank.

Probably just bad luck + unknown previous maintenance and oil change intervals (you got car from auction in Apr and 6 months later engine failed).

Also, I personally would not perform any home-brewn bugfixes to the way N55 oil pump operates, this can result in unknown problems down the line.
Just change oil max at 15 000km and see how it performs.

Good luck!

EDIT: My 10 cents what is killing the BMW engines. I have serviced all my BMWs at local specialist here in Tallinn over last 25 years and their conclusion is that major BMW engine faults are usually caused by BMW Service Inclusive program with on-demand oil change intervals. This means oil is changed at 35-40 000km (20-25 000 miles (!). It means clog build-up, excessive wear and oil flow problems. Combined with short city stints with cold engine/low rpm/excessive load it is a disaster for any engine. When someone buys the used car after 3 years and 100 000 km / 60 000 miles, switching to 6000-10 000 miles oil change interval might not save from already incurred damage and wear. Flushing such engine prior to switching to shorter oil change intervals also involves a very high risk and is not recommended, as this might dislodge excessive clog and cause permanent blocking of tighter oil passages. Remapping / reasonable tuning of engines in a good condition has not been issue at all to engines reliability. In a conclusion, when buying older BMWs just apply some common sense and mechanical sympathy:

- review all previous maintenance records. No records - walk away. Long oil change intervals do less damage, if car was driven daily on highway/autobahn.
- switch to shorter oil-change interval (max 10 000 miles / annually), use good quality approved spec oils. There are no miracle snakeoils out there to fix already worn engine.
- monitor oil consumption & patterns. Under track or high rpm use, oil consumption will go up because of the blow-by.
- do not overstress cold engine
- look out for any unnatural noises
- and at least a weekly basis do a nice 100+ miles roundtrip.

Originally Posted by AbbeyRoad

Post 3:
The oil starvation and rod failure problems with the N55 seem to have two causes. The first is hard turns on the track, and this is fixed using: the S55 secondary oil pump; and/or oil pan baffle system; and/or overfilling oil.

The second cause is unknown and is fixed by: computer remap to raise oil pressure; and/or harder aftermarket bearing shells; and/or replacing various components like the oil pickup; and/or special oil or oil replacement schedules.

Here is my own discovery that the N55 variable rate oil pump can never work properly long-term IMO. My plan is to drill a strategic hole in the pump and to flip the piston in the video, to block the variable rate mechanism of the pump.

[ThicF30]

Is there any oil level Sensor offered that could bring up the height another half inch to an inch? Doing so would increase the volume of the oil, especially in the Xdrive oil pan. it appears with the suction plate installed there is still room For the sensor to be brought up higher before it comes in contact with the suction plate.

[AbbeyRoad]

Post 5:

[AbbeyRoad]

Post 6:

Here are the DME codes for the N55.

https://objectivelyspoken.com/upload...DME-codes.htmz

Notice that there are two codes related to "oil pressure too high". Both codes have off/none in column "MIL illumination..."

- ECE emissions warning lamp: off
- ECE electronic engine power reduction: off
- CC message: none
- US emissions warning lamp: off
- US electronic engine power reduction: off
- CC message: none

So I might get a code, but I won't get a CEL and I won't fail inspection.

[AbbeyRoad]

Originally Posted by LA1Z24

The DME ...

See Post 6 and see if you agree. Yes, this is the most important question. I am very interested in more info on this.

Originally Posted by ThicF30

There is...

Thanks

Originally Posted by Ilvez

... design... shells... matched... luck... bugfixes... 15 000km... on-demand... overstress...

No. no. no. no. no. no. no. no.

Originally Posted by ThicF30

Is there any oil level Sensor offered that could bring up the height another half inch to an inch?

yes. web search should find it. i am not an expert - could be a bad idea.

[AbbeyRoad]

Post 7:

Originally Posted by ThicF30

..... assure it never occurs again.

https://www.urotuning.com/products/a...in-bearing-set

These ACL bearings are very interesting: the groove goes more than 180 degrees. Probably also solves the rod-bearing problem.

Some general discussion on grooves here: MAHLE-Motorsport-Groove-bearings-techincal.pdf

https://marmotorsport.com/wp-content...-techincal.pdf

[Ilvez]

What do you mean by disagreeing?

What was your car service interval before you bought it? How often did you change your oil until it failed? What were your driving habits/oil consumption?

As I said, there are millions of N55 engines out there and engine seizing up on a steady drive with 3 shells cooked is almost unheard event and not evidence at all to a systematic N55 oil pump failure as you are alluding.

Your statement that harder shells are a fix is completely wrong because by definition when a shell contacts crank journal, it is a failure.

BTW. There is no systematic “rod bearing problem” with N55/S55 engines as opposed to S65/S85 ones.

As far as I can see you had very rare engine failure, most likely related to extended oil service intervals/blocked oil passage/oil pump failure and now you for some reason try to blame N55 oil pump design.

Originally Posted by AbbeyRoad

No. no. no. no. no. no. no. no.

https://f30.bimmerpost.com/forums/showpost.php?p=31747794&postcount=7

[AbbeyRoad]

Originally Posted by Ilvez

What ...

I am not interested in arguing. Please do not post again on my threads.

[Ilvez]

FYI, I am not arguing by far, sorry if you feel such way. If you claim that N55 oil pump design is faulty, it is a massive claim, which you need to back up with facts and not spread panic among rest of N55 users.

Why are you not disclosing previous and your maintenance history of your N55 car?

Again, N55 engine seizing on a leisurly drive with 3 damaged crank shells due to lubrication failure is super rare and isolated event.

[spite]

Be careful with the oil pressure, N55 pump is powerful one, just by disconnecting the control solenoid the pressure is over 6 bar in 1500 rpm, while this seems like a good thing it may strain the components and result in premature failure of some hydraulic components. This will also create good environment for oil filter deformation and oil filter by-pass circulation due to the increased oil flow during cold starts. Turning the piston or deleting the variable flow function I suspect will make the pump work even harder and may reach even higher pressures.
Don't forget that the VVT gears are held together via aluminum bolts which are prone to failure.

If you need higher pressure best way would be to tune that out or try to use the N54 oil pump which does not have electronic pressure control, hence it's pressure is rpm dependent rather than being load dependent as N55/S55 one is
With electronic oil pressure control:


With disconnected electronic oil pressure control:

[Ilvez]

Finally, thanks a lot for a solid info. The whole thread has been very strange for me to read. OP has over weeks not said anything about his car maintenance schedule, the whole engine seizing incident points to a bad luck and most likely very extended oil change intervals, which OP is trying to attribute to N55 oil pump design. Craziest of all is suggestion to "fix" this by drilling a "strategic hole" and flipping a pin inside the pump. Probably just trying to get some subs for his channel.

Originally Posted by spite

Be careful with the oil pressure, N55 pump is powerful one...

[spite]

Originally Posted by Ilvez

Finally, thanks a lot for a solid info. The whole thread has been very strange for me to read. OP has over weeks not said anything about his car maintenance schedule, the whole engine seizing incident points to a bad luck and most likely very extended oil change intervals, which OP is trying to attribute to N55 oil pump design. Craziest of all is suggestion to "fix" this by drilling a "strategic hole" and flipping a pin inside the pump. Probably just trying to get some subs for his channel.

Just to make some things clear, I do believe that N55 has some oiling issues not related to the long OSI and my post was intended to be informational and helpful. I do not want to judge anyone, I have done some test mods to the oiling system myself.

On topic: Since I forgot to add some context, the data in my previous post is from my own car on 270k km(stock). Logs are made through MHD and show some daily driving plus some 1/4 mile pulls. Oil used is Mobil1 5w50 at around 100*C.

Edit: AbbeyRoad, can you please share the condition of your main bearings, oil starvation or OSI related problem will show some signs of wear throughout all of the crank bearings.

[AbbeyRoad]

Thanks Spite. You make many important points.

Originally Posted by spite

6 bar in 1500 rpm, while this seems like a good thing it may strain the components and result in premature failure of some hydraulic components.

Which components? I have disassembled everything and my engineering estimation is that nothing would suffer. My only concern is the oil drive chain and guides may not last as long. Perhaps I should put in an oil squirter to keep the chain aggressively oiled.

I am an Aeronautical Engineering graduate BTW, so I am making a calculated judgment here.

Originally Posted by spite

This will also create good environment for oil filter deformation

The more expensive filters are rigid enough IMO.

Originally Posted by spite

by-pass circulation

The oil over-pressure by-pass is a spring* and ball in the pump body. It shoots excess oil right back into the pan rather than being pumped up to the filter. It sure will be working overtime - LOL, but that just makes the oil a tiny bit hotter.

Originally Posted by spite

due to the increased oil flow during cold starts. Turning the piston or deleting the variable flow function I suspect will make the pump work even harder and may reach even higher pressures.

Yes..... just like every engine without a variable-rate oil pump!

The pump cannot reach higher pressures than the spring* pressure.

Originally Posted by spite

Don't forget that the VVT gears are held together via aluminum bolts which are prone to failure.

That's pre-2011. Mine are steel.

Originally Posted by spite

try to use the N54 oil pump which does not have electronic pressure control, hence it's pressure is rpm dependent

Yes, this is a good idea. I am still considering it. I was going to use the N52 pump which is the same as the N54, IIRC.

However I really want to get rid of the pump pivot which I believe is a fundamentally unreliable design.

You see there are all these cams on ebay with scoring. This tells me pressure did not keep up at some point in the RPM/load landscape. Even my N52 had some cam scoring, which doesn't seem right to me. My mopar cam had pitting before scoring - at 220 thousand miles!!!!

Originally Posted by spite

With disconnected electronic oil pressure control

I love that chart.

:

YES! I WANT THAT 100%!! LOL!

[Ilvez]

Originally Posted by spite

Just to make some things clear, I do believe that N55 has some oiling issues not related to the long OSI and my post was intended to be informational and helpful. I do not want to judge anyone, I have done some test mods to the oiling system myself.

On topic: Since I forgot to add some context, the data in my previous post is from my own car on 270k km(stock). Logs are made through MHD and show some daily driving plus some 1/4 mile pulls. Oil used is Mobil1 5w50 at around 100*C.

Thanks for info! What mods have you done to N55 oiling system? I have used 5W-40 for last 10+ years for my tuned N55 with excellent results. 50 grade oil seems bit thick for N55.

[AbbeyRoad]

Originally Posted by spite

AbbeyRoad, can you please share the condition of your main bearings, oil starvation or OSI related problem will show some signs of wear throughout all of the crank bearings.

About half the bearings had heavy scoring, both rods and mains. Yikes, it's was BAD in there! And most likely this started long before I got the vehicle because there was a bunch of metal in the filter when I got the car. I was running 15W50 to compensate for bearing wear.

It is entirely possible that the last hard pull I did sucked some air into the oil pickup. The oil was low-ish. I guess we will never know. I would like to think it is impossible to suck air into the pickup on ANY car unless the oil level is below the MIN mark. But maybe BMW messed up.

[Ilvez]

This is either some dark comedy or just a really sad story. Just to recap:

- OP is a trained aerospace engineer
- OP buys a car with unknown maintenance history AND with a full knowledge that there are metal flakes present in the engine oil, before still proceeding on to use the car daily
- OP fills car with much thicker oil of 15W-50 than approved by BMW in N55 engines in a hope to compensate for a previous wear(?!)
- OP does some "hard pulls"
- Engine seizes after 6 months of usage
- OP sets up a Youtube channel to explain how BMW N55 oil pump has inherent flaws, which could be "fixed" by drilling a "strategic hole" into N55 oil pump.

...

Originally Posted by AbbeyRoad

About half the bearings had heavy scoring, both rods and mains. Yikes, it's was BAD in there! And most likely this started long before I got the vehicle because there was a bunch of metal in the filter when I got the car. I was running 15W50 to compensate for bearing wear.

It is entirely possible that the last hard pull I did sucked some air into the oil pickup. The oil was low-ish. I guess we will never know. I would like to think it is impossible to suck air into the pickup on ANY car unless the oil level is below the MIN mark. But maybe BMW messed up.