[7tune]

Originally Posted by M2guru

In hindsight, what I didn't do in the oil pressure test was what the factory recommends for the number of times to crank the engine over. I did it once and when the oil pressure reached a normal pressure, I considered it done/OK. When I do it over again, I'll do what the factory recommends because I believe pressure and getting the air out of the system are likely two different things. In other words, you can have good pressure, but air moving through the system could cause a dry situation that MIGHT not be seen in the pressure reading.

Hm. The way that reads is that it may be a combination of lower than acceptable oil pressure due to an incomplete purge of the system plus air creating locks.

I do recall F87source mentioning this earlier in one of the threads and wondered why he said that but most likely because that’s an ISTA service mandatory treatment. And it was just before your later posts.

It freaks me out a bit because the OFHG is such a simple and innocuous set of gaskets with a very simple procedure for exchange but it can , and obviously has for other M2 owners, either damaged or destroyed entire engines.

The same applies for any of the oil related carriage, hence my concerns about doing oil changes, as I would naturally consider these serviced to be “breaking seal” and “introducing air into the system”.

Doubtless a purge is critical when changing coolers and gaskets but it’s crazy that the consequences of such an innocuous procedure could result in something as serious as catastrophic turbo or engine failure.

If indeed it’s only the turbo then I believe you’re fortunate. Still… if there is air in the lines and the turbos were starved of both oil and pressure then it makes sense why the input shaft was the first thing to go as it’s likely overheated and spun itself free, since it’s literally the link between the housings.

I feel for you mate, and hope you see it back on the road soon. Subbed to your progress!

[F87source]

Originally Posted by 7tune

Hm. The way that reads is that it may be a combination of lower than acceptable oil pressure due to an incomplete purge of the system plus air creating locks.

I do recall F87source mentioning this earlier in one of the threads and wondered why he said that but most likely because that’s an ISTA service mandatory treatment. And it was just before your later posts.

It freaks me out a bit because the OFHG is such a simple and innocuous set of gaskets with a very simple procedure for exchange but it can , and obviously has for other M2 owners, either damaged or destroyed entire engines.

The same applies for any of the oil related carriage, hence my concerns about doing oil changes, as I would naturally consider these serviced to be “breaking seal” and “introducing air into the system”.

Doubtless a purge is critical when changing coolers and gaskets but it’s crazy that the consequences of such an innocuous procedure could result in something as serious as catastrophic turbo or engine failure.

If indeed it’s only the turbo then I believe you’re fortunate. Still… if there is air in the lines and the turbos were starved of both oil and pressure then it makes sense why the input shaft was the first thing to go as it’s likely overheated and spun itself free, since it’s literally the link between the housings.

I feel for you mate, and hope you see it back on the road soon. Subbed to your progress!

Yeah you really need to purge the system multiple times to ensure all air locks are completely gone. Doing it one time is not enough.

[M2guru]

Finally finished disassembly of the turbo. This was my first time digging into a turbo as deep as possible, so I had to do a bit of research before I tore it apart.

First picture: Here are the parts in order and consistent facing - all parts are as they came off.

Second picture: Here is the thrust bearing. Based on what I see, it wasn't wear damage, but rather after the shaft broke it wobbled around and banged up the bearing surface tabs.

Third picture: Here is the compressor/cold side journal bearing. This one is loose on the shaft. It is closest to where the shaft broke. As you can see, there are holes on the outside of the journal bearing, but due to wear the inner hole has been filled in with the bearing's own brass - blocking oil flow. (There is one hole for each notch on the top.) I think this, too, is a result of the shaft breaking because I don't see significant discoloration, which would indicate heat, on the shaft and also the outer bearing is not worn (additionally, there was no sludge anywhere).

Fourth picture: Here is the turbine/hot side journal bearing where you can see the hole goes all of the way through. This bearing fits tight and appears to be fine.

This was a helpful source to understand the inner workings: