[pmsteinm]

So I assume leakdown would mean leaking valve stem seals or piston rings (or injectors orings). I know valve stems were a problem on the F10 and earlier (there is a SIB for that) but supposed ok now and not related to coolant leaks. I guess if the injectors were dumping lots of fuel in they could have washed oil off the cylinder walls and caused scoring, or lean could have gotten things too hot. Still surprised you didn't get a check engine light but maybe things just weren't bad enough to trigger. Maybe it was death by a 1000 cuts since the problem seems to have been there a while. Let us know what they end up replacing and fixing.

[imperfectluck]

The pain point I see is that checking the expansion tank is something that’s now apart of routine maintenance. Sigh, such a great engine with a bit of a flaw that really should be remedied but our words fall upon deaf ears as the S68 is now their focus.

[Oz M5]

The INDI did report that the injector on cylinder 7 was stuck open, from what looked like contamination from a previous reservoir tank failure. They couldn't detect any scoring with a camera however based on the final diagnosis, especially when they detected air being released through the oil cap during the leakdown test, in my uneducated opinion I'd suggest the bore of cylinder 7 has been washed.
Waiting for RK to start pulling it down to ID the actual issue, but maybe looking at needing to Sleeve the bores! 😞
But I do think it strange that the CEL did not come on until after final diagnosis.
Ah well... far worse things going on in the world right now!

[BlueSander]

Originally Posted by Oz M5

The INDI did report that the injector on cylinder 7 was stuck open, from what looked like contamination from a previous reservoir tank failure. They couldn't detect any scoring with a camera however based on the final diagnosis, especially when they detected air being released through the oil cap during the leakdown test, in my uneducated opinion I'd suggest the bore of cylinder 7 has been washed.
Waiting for RK to start pulling it down to ID the actual issue, but maybe looking at needing to Sleeve the bores! 😞
But I do think it strange that the CEL did not come on until after final diagnosis.
Ah well... far worse things going on in the world right now!

I rmb reading that your car has a tune installed right? was it done by you or the previous owner?

Sorry to hear of what you are experiencing! Hope you get it sorted out soon!

[Oz M5]

Originally Posted by BlueSander

I rmb reading that your car has a tune installed right? was it done by you or the previous owner?

Sorry to hear of what you are experiencing! Hope you get it sorted out soon!

I did have the Racechip piggyback installed but doubt that caused the issues.

Not sure if had any tunes in its previous life.

[pmsteinm]

Originally Posted by Oz M5

I did have the Racechip piggyback installed but doubt that caused the issues.

Not sure if had any tunes in its previous life.

I would expect that it would. It takes various data going into the DME and fudges the values to make it give you more power. That means the DME is operating on invalid data. Who knows how it handles errors and corner cases and how the tuner software handles things (which has limited ability to because it can't see/adjust everything).

Piggyback tunes seem like a hack job to me. A full flash is better (if possible, for LCIs sending it to Russia for unlock seems even more sketch) but still does the tuner really know everything the proprietary BMW tune was doing? And how does the piggyback affect the DME trying to adjust for injector variance and wear and tolerances? Then when the injector current/voltages go nuts because of coolant corrosion what happens to all this?

Hearing that you had a piggyback makes me feel better that for most of us if the injectors go nuts something will flag it in DME.

In all software and hardware design the designers make assumptions about things. Piggyback tunes and coolant damaging injectors can violate those assumptions. If they didn't design it to handle unexpected things then it makes sense that bad things can happen to the engine. I would love to talk to an engineer that actually worked on the DME and ask how does it handle the injector failure modes (including modes that I assume they didn't expect since they probably didn't think the tank would leak).

[pbonsalb]

There are cases of leaking coolant tanks causing injector failure and/or coil failure and ruining totally stock F90 M5 engines. BMW dealers have replaced some under warranty and they would not do that if they could find a way to deny coverage.

[CrashCade]

I saw a post yesterday that BMW issued a stop sale on F90s due to the reservoir tank issues. They don’t have a path forward at this point yet though.

[SeatownF80]

Originally Posted by CrashCade

I saw a post yesterday that BMW issued a stop sale on F90s due to the reservoir tank issues. They don’t have a path forward at this point yet though.

Yeah, I'm kinda boned if they dont act soon. My tank is leaking and the replacement I ordered is "delayed". Its my daily too.

[Oz M5]

Do we know if the tank is going to be any different?

[Justao]

Originally Posted by Oz M5

Do we know if the tank is going to be any different?

There is a new reference coolant reservoir since 2022, but unfortunately it fails as well…

[FJPM]

Originally Posted by Demon Barber

New part number is 17-13-7-889-450

Is the part number visible without dismantling the tank?

[fun2drv]

My car is a May 2023 build and out of the inclusive dates of the service bulletin. Not sure why. I only have 10K miles and have seen dried white coolant around the cap…

[Alberta]

Originally Posted by FJPM

Is the part number visible without dismantling the tank?

I checked but I couldn't find it.

[Oz M5]

Originally Posted by Justao

There is a new reference coolant reservoir since 2022, but unfortunately it fails as well…

I'm just curious to know if this replacement program is with a 3rd revision of the tank. 🤔

[Oz M5]

Originally Posted by pmsteinm

I would expect that it would. It takes various data going into the DME and fudges the values to make it give you more power. That means the DME is operating on invalid data. Who knows how it handles errors and corner cases and how the tuner software handles things (which has limited ability to because it can't see/adjust everything).

Piggyback tunes seem like a hack job to me. A full flash is better (if possible, for LCIs sending it to Russia for unlock seems even more sketch) but still does the tuner really know everything the proprietary BMW tune was doing? And how does the piggyback affect the DME trying to adjust for injector variance and wear and tolerances? Then when the injector current/voltages go nuts because of coolant corrosion what happens to all this?

Hearing that you had a piggyback makes me feel better that for most of us if the injectors go nuts something will flag it in DME.

In all software and hardware design the designers make assumptions about things. Piggyback tunes and coolant damaging injectors can violate those assumptions. If they didn't design it to handle unexpected things then it makes sense that bad things can happen to the engine. I would love to talk to an engineer that actually worked on the DME and ask how does it handle the injector failure modes (including modes that I assume they didn't expect since they probably didn't think the tank would leak).

Interesting point. What you're suggesting is that whilst the Racechip wouldn't cause the issue, it may interfere with the ECU being able to detect faults with the injectors and thus not activate the CEL.

As of this morning the Engine is out. I'm waiting patiently to see what the diagnosis is....

[M5_1of400]

Originally Posted by Oz M5

Interesting point. What you're suggesting is that whilst the Racechip wouldn't cause the issue, it may interfere with the ECU being able to detect faults with the injectors and thus not activate the CEL.

As of this morning the Engine is out. I'm waiting patiently to see what the diagnosis is....

Always gut wrenching seeing your baby go thru open-heart surgery like this.

[pmsteinm]

I would love to be able to DIY something like that, but it requires a full lift (not QuickJack). And a 2nd car to drive for the many days it would take me to complete the task.

There was a thread on an F10 forum about someone doing their own valve stem seal replacement (which BMW had trouble with on that gen N/S63 but theoretically fixed). It looks like a huge job but something I would rather DIY then trust the new hire lube tech at the dealer to do.

Keep in mind all tunes can cause issues. The manufacture builds all kinds of margin into the factory tune to cover high altitude, extreme temps, variable fuel quality, fuel efficiency, reliability, and who know what else. Tunes take some of that margin away to give you more power. So you always run the risk that something bad can happen because the tune doesn't have as much margin left. Like a lean condition on 1 cylinder. But most of the time it's fine which is why so many people get away with it. But it is very telling that pretty much every used car advice thread says walk away if ever tuned. What does that tell you?

When I had my 09 CTS-V many people tuned and changed the pulley to get more power. I felt like the risk was never worth it, even out of warranty. Especially since I'm WOT every chance I get. The statistics would catch up to me so I want the manufacturer's margin in place. FWIW I sold that car after 14 years with 104k miles, having bounced off the rev limiter countless times.

Oz M5 I hope you get your car back together soon and hopefully it isn't too bad. And I hope that stop sale leads to a fix, but I think they are just going to use the latest tank which it is not clear if that really fixed it or not. But I'd rather the coolant tank be an issue than rod bearings. It is a German car, so it has to have at least one mechanical quirk.

[Oz M5]

Originally Posted by pmsteinm

I would love to be able to DIY something like that, but it requires a full lift (not QuickJack). And a 2nd car to drive for the many days it would take me to complete the task.

There was a thread on an F10 forum about someone doing their own valve stem seal replacement (which BMW had trouble with on that gen N/S63 but theoretically fixed). It looks like a huge job but something I would rather DIY then trust the new hire lube tech at the dealer to do.

Keep in mind all tunes can cause issues. The manufacture builds all kinds of margin into the factory tune to cover high altitude, extreme temps, variable fuel quality, fuel efficiency, reliability, and who know what else. Tunes take some of that margin away to give you more power. So you always run the risk that something bad can happen because the tune doesn't have as much margin left. Like a lean condition on 1 cylinder. But most of the time it's fine which is why so many people get away with it. But it is very telling that pretty much every used car advice thread says walk away if ever tuned. What does that tell you?

When I had my 09 CTS-V many people tuned and changed the pulley to get more power. I felt like the risk was never worth it, even out of warranty. Especially since I'm WOT every chance I get. The statistics would catch up to me so I want the manufacturer's margin in place. FWIW I sold that car after 14 years with 104k miles, having bounced off the rev limiter countless times.

Oz M5 I hope you get your car back together soon and hopefully it isn't too bad. And I hope that stop [...]

Thanks mate.... and you're right regarding the piggyback. She's remaining stock when she back!

[FJPM]

Originally Posted by fun2drv

My car is a May 2023 build and out of the inclusive dates of the service bulletin. Not sure why. I only have 10K miles and have seen dried white coolant around the cap…

Are you sure that the cap was properly closed. It can be hard to turn it to th arrow?

[fun2drv]

Originally Posted by FJPM

Are you sure that the cap was properly closed. It can be hard to turn it to th arrow?

Yes, this is my second F90 and I have been dealing with the tank issue since 2019.



Not sure why the Service Bulletin doesn't include my car. It should cover every F90 until end of production...

[NGT2]

Originally Posted by pbonsalb

The one on the driver’s side is the engine coolant tank. It seems to be the more common problem. White residue is a sign of leaking. Inspect carefully all around since some say there were no obvious signs on the top or front.

Responding to and old comment and mine was M550 but same general issue - white residue leaking from the seam and also onto the hose.

I got a low coolant warning. Upon inspection, tech found the residue. I saw it on the video he sent. You’d be able to see it yourself if you’re looking for it.