[pete_gpx]

Well, really feel like I'm part of a statistic at this point.

My name is Pete, and I now own a useless paperweight of an engine, attached to my 2011 335i.

After taking the car off the road to replace the clutch, flywheel, OFHG, valve cover gasket, plugs, coils, new oil and filter, my engine has seized after driving for approximately 20 minutes.

I'd read the stories of owners with early model E series N55s experiencing issues, mainly rod bearing failure, after doing basic maintenance work. I followed all the recommendations online, making sure to crank the engine several times before starting to allow for oil to circulate. I filled half a litre of oil through the oil filter itself to make sure everything was well lubricated. I idled the car for 5 minutes before driving to make sure everything was fine. Despite this, at 60km/h (37m/h), at around 50% throttle in 4th gear, the engine shutoff suddenly and my rear tires began to chirp as I slowed. A quick tow home later from my mechanic friend and several head scratching attempts to restart the car and wondering aloud what was wrong, the diagnosis is in; the motor can not be turned by hand and is seized.

The car currently has 97000 kilometers (60000 miles) on it. I've owned it since 82000KM and have changed the oil three times, always with full synthetic Castrol Edge 5W-30.

It's mildly modified, with a JB4, VRSF catless downpipe, BMS intake and charge pipe, all done during my ownership.

I was very careful while changing the OFHG (this is the second time in my three and half year ownership that I've done it) and am sure no rag, bolt or screw made its way down the oil passages.

I genuinely don't know what I did wrong to bring this on, but I can say for sure that I will not be putting another N55 back in the car. All is not lost as my mind is already working on a motor swap to something a little... Larger in capacity.

Anyway, thought I'd post up to lend my voice to say; there is something wrong with these early E series N55s. If you own one, I recommend having your OFHG replaced at a reputable workshop that has insurance to cover any possible failures thereafter.

[NoGuru]

Sorry to hear about this. I am sure it is a strain.

But like you said, you get to put a new motor in. N54 or B58?

[Chris1337]

After changing the ofhg you need to prime oil lines by pulling coils and turning the engine over.

[TheMidnightNarwhal]

Another one...

[drwillb]

Sorry to hear about your problem. I'm sure new cases will keep popping up on the forums over the years.

I did a maintenance rampage same as you (plus a PS1 turbo) in August of 2018. At the time, I hadn't read about any of these post-OFHG seizures and I think I would have definitely handed off the job had I known.

Anyway, not having the service bulletin, I didn't do any of the oil pump priming prior to first start. The only precaution I took was to use compressed air to clean out the area around the OFH and then scrub with a brush to remove any loose road debris.

I don't know and probably nobody knows the cause of this problem but I'm inclined to think that it is small debris that gets into the oil system past the filter stage, because it's all gutted while doing the job, and then works its way to the bearing oil passages. It wouldn't take much at all, either. Think of it like a kidney stone. Something the size of a grain of ground up pepper can cause a lot of problems.

But maybe I just got really lucky that day.

Good luck with the car. Here's a chance to make it better.

[pete_gpx]

Originally Posted by Chris1337

After changing the ofhg you need to prime oil lines by pulling coils and turning the engine over.

Yep, turned it over a bunch of times before starting it.

Originally Posted by NoGuru

Sorry to hear about this. I am sure it is a strain.

But like you said, you get to put a new motor in. N54 or B58?

I'm thinking something with 8 cylinders

Originally Posted by drwillb

Sorry to hear about your problem. I'm sure new cases will keep popping up on the forums over the years.

I did a maintenance rampage same as you (plus a PS1 turbo) in August of 2018. At the time, I hadn't read any of these post OFHG seizures and I think I would have have definitely handed off the job had I known.

Anyway, not having the service bulletin, I didn't do any of the oil pump priming prior to first start. The only precaution I took was to use compressed air to clean out the area around the OFH and then scrub with a brush to remove any loose road debris.

I don't know and probably nobody knows the cause of this problem but I'm inclined to think that it is small debris that gets into the oil system past the filter stage, because it's all gutted while doing the job, and then works its way to the bearing oil passages. It wouldn't take much at all, either. Think of it like a kidney stone. Something the size of a grain of ground up pepper can cause a lot of problems.

But maybe I just got really lucky that day.

Good luck with the car. Here's a chance to make it better.

Definitely can not be sure that not a single speck of dirt went down the oil galley, but I was quite careful. The old gasket left some hardened residue on the alloy housing, and I used a gasket scraper to get it off, but had a rag covering the holes at the time to be sure none went down. Of course, I can't say for certain that something didn't make its way down... But it would have had to have been damn small.

Thanks for the kind words, definitely will 'seize' this opportunity to improve the car.

[lwgrenier]

I honestly think it's worth taking the car to a BMW dealership to have the OFHG changed. I know it's big $$$ but might be worth it on the off chance this happens.

Originally Posted by Chris1337

After changing the ofhg you need to prime oil lines by pulling coils and turning the engine over.

That's not how you do it but he said he primed the oil system.

[lwgrenier]

Originally Posted by pete_gpx

I'm thinking something with 8 cylinders

Saw this the other day
https://lse90.com/

[pete_gpx]

Originally Posted by lwgrenier

Saw this the other day
https://lse90.com/

Saw that too

[carguy138]

@Pete_GPX

Really sorry to hear that.

By any chance does your car have the sport oil cooler?

Just a theory here with nothing to back it up...

If the car is equipped with an oil cooler and oil cooler thermostat which only opens at 245 degrees. Could there be a chance that an air pocket forms between the OFH and pump location? Effectively allowing it to run dry after opening up the oil filter housing until the engine is up to temp and the oil thermostat opens?

No idea if this is how it actually works, just trying to think outside the box.

[drwillb]

Carguy138, the oil cooler thermostat is just like an old school water coolant thermostat. It's a metallic spring that expands and contracts in the specified temperature range and controls the oil flow passage with a metal piston that blocks the openings. The (movement of the piston) opening of the oil passages into and out of the oil cooler occurs slowly so that air can flow out slowly if there is an air bubble.

My car has the ER race oil coolers and I did not bleed them while hooking them back up to the thermostat. However, I've since replaced both coolers over the last 12 months and I have an urge to check to make sure there is no air trapped in them. Both the inlet and outlet fitting for these are at the bottom of the coolers and I'm not sure how the oil is routed through them but I can't see how they would self-bleed.

[9krpmrx8]

Sucks man. There are so many variables though.

[TheGoodTheBadTheUgly]

Wow this is simply amazing, I can't begin by expressing how bad I feel for you mate. At this point, I don't think anyone can find a specific explanation for this failure.

If I were you, I would honestly just go for an N54 with a 6466 Turbocharger, really hard to beat that combo even with bigger engines. It's just that you are staying in the realm of N5X engines which sucks a bit because they share some common failures.

Do you know the production month?

[9krpmrx8]

I really wish someone have a proper tear down and inspection done by someone who is unbiased on one of these failures.

[Pladi]

It might be hard for you to wanna pick n55 as a replacement since u probably dont trust them anymore but i think it still makes most sense.

- more of them out there
-less costly and complex to install on ur frame
- still capable of tons of power
- chances of another one failing this way statistically are very very low.

Personally, unless you have another very good reason or a specific reason i dont see why you would want to install anything else.

Now if u just have the time and money to experiment go right ahead.

[xxMike61]

Wow. When I did mine earlier this summer I went to the back seat and took off the bottom seat and pulled the power to the fuel pump. Then I started the car till it stalled out. And another crank just for good measure.

I was super careful with the oil filter housing and the cooler. ( I changed both gaskets) Cleaned everything with brake cleaner once it was off and the face where the gasket meets the flat block.

When everything was back together I didn't even top off the oil or coolant. But I did go back into the car and cranked it for a good 10 seconds 5 times (Before plugging the fuel pump back in) I then let it idle all the way till it was operating temp for me which is ~250. Crazy how often these cases pop up on the forums.

[N55lif3]

Just did my OFHG on my early n55. Sorry to hear about your mishap

[Wolf 335]

Why would you need to prime your oil system after OFHG change?

[feuer]

Originally Posted by drwillb

Carguy138, the oil cooler thermostat is just like an old school water coolant thermostat. It's a metallic spring that expands and contracts in the specified temperature range and controls the oil flow passage with a metal piston that blocks the openings. The (movement of the piston) opening of the oil passages into and out of the oil cooler occurs slowly so that air can flow out slowly if there is an air bubble.

Is wax loaded thermostat.

[drwillb]

Originally Posted by Wolf 335

Why would you need to prime your oil system after OFHG change?

Right. Doesn’t make sense but the factory says that this is the correct method. This is on a service bulletin after they had enough oil starvation seizures.

Doesn’t make sense. When you change the oil filter, aren’t you letting air into the system and all the oil drains into the pan? Is there a check valve in the OFH that prevents this from happening even when you open it to change the filter? I don’t think so.

My money is still on 1 or 2 mm sized debris getting in during the OFHG job.

[drwillb]

Originally Posted by feuer

Is wax loaded thermostat.

Is spring pushing on piston

[feuer]

Originally Posted by drwillb

Is spring pushing on piston

Yes, but there is a wax capsule that allows the spring to push the piston as temperature changes.