[Ryno 27]

28k miles, has anyone experienced this with their M5?

[DryBark]

There are a few blown engines on this site right around that mileage mark due to this.

[pbonsalb]

I think those reports concern the coolant tank. The OP did not specify the area of leak.

[AP]

Just look on the g30 forums, plenty of us that experienced this including myself

In my case it was the 2 reservoirs having a minute crack . So only very small amounts escaping but over time it will trigger low coolant warning

Fixed under warranty for me

Don't be robbed off by dealershipnsaying a small leak is normal as it isnt

[Aronis]

No leak is 'normal.' Poor design.

Mike

[UglyBuzzard]

Yep - reservoir replaced at 27k…

[Maverik259]

heat soak is killing the cheap bmw plastics. always has and always will. especially the hot v design. cheap plastic on some oil return lines in my X5 50i disintegrated only to find out they replaced with new rubber lines 6 months after my build date.

[DryBark]

Originally Posted by pbonsalb

I think those reports concern the coolant tank. The OP did not specify the area of leak.

You're right, I jumped to worst case scenario 😂

[AHall]

Originally Posted by DryBark

You're right, I jumped to worst case scenario 😂

Yeah right, blown engines???

[pbonsalb]

Some reports were that the coolant damaged wiring that caused problems but I can’t recall what wiring—into spark plug holes?

[WayneM3]

The coolant tank leak on mine at around 25,000 miles led to failed direct injectors. The first dealer (who had the car for 4 weeks) told me that my head gasket was blown and wanted $8,000 to fix it due to the fact that my car was flagged for a tune and they claimed the tune caused the head gasket to fail which led to "overpressurizing" the coolant tank and caused it to crack. The second dealer replaced everything under warranty because, surprise, my head gasket was not blown and this is a known issue.

[pbonsalb]

So coolant shorted the electrical connection at the top of the direct injector?

[afk8445]

1. got low coolent warning
2. went to dealer, topped off (turbo coolent)
3. same day, drivetrain malfunction, lost power, limp mode
4. back to dealer, turns out coolent leaking, affecting turbos, and needs to replace radiator and a whole bunch of things (dont know full details yet)
5. BMW authorized repairs, parts took about a month to arrive
6. once fix is done will update.

32K miles, 2018 F90

[WayneM3]

Originally Posted by pbonsalb

So coolant shorted the electrical connection at the top of the direct injector?

Yes - multiple injectors were replaced. I cannot say for sure exactly what was wrong with them but they replaced all 4 on the driver's side of the engine.

[AHall]

I wonder what it will take for BMW to be proactive and resolve this issue. Replacing the failed tanks with an exact copy will likely fail again.

[WayneM3]

Originally Posted by AHall

I wonder what it will take for BMW to be proactive and resolve this issue. Replacing the failed tanks with an exact copy will likely fail again.

Exactly! I am up for an aftermarket one once somebody figures it out.

[DryBark]

Originally Posted by WayneM3

Exactly! I am up for an aftermarket one once somebody figures it out.

Someone took theirs out and coated it with something, can't remember what. I think another person had one custom made as well.

[Rippy]

I went on holidays for 2 weeks and my car sat in my garage for that time. Temperature in garage is roughly 26°C. When I got back I fired the car up and got a low coolant warning. I topped up both coolant locations, the main needed roughly a cup and half. Not very much. Should I be concerned? Car has roughly 22k miles on it. A low coolant warning came on one other time as well.

[imolaa_m5]

Happened to my LCI brand new 22 at just 1.7k miles. The cap on the coolant tank failed and started leaking coolant out the expansion dripped down into all 4 injectors in that area. Was replaced by bmw under warranty but shouldn't be happening I second a aftermarket tank / cap solution

[Ryno 27]

Thanks for the responses. I never did get the low coolant warning. I brought the car in for brake fluid service and the tech noticed the leak near the fill cap. The expansion tank was replaced and injector wells had to be cleaned due to the leak. Definitely have concerns about this happening again. I just bought the car out of my lease, however did opt for the extended maintenance and warranty thankfully.

[Maverik259]

Originally Posted by DryBark

Someone took theirs out and coated it with something, can't remember what. I think another person had one custom made as well.

it was heat reflective tape. its what comes on the Eventuri air box's

[pbonsalb]

It was me. DEI 2” fiberglass heat reflective tape. I be also applied it to the underside of the upper metal heat shield (the one the tank bolts to). I used a new tank since my car was 4 years old and it seemed like a good idea to replace it preventatively based on what I read here on motor failures due to coolant leaks.