[ljb]

I also had the coolant leak from a crack in reservoir (~24k miles). Car was in the shop for 8 weeks waiting on parts.

[pbonsalb]

Was a cause specified? The belief had been that heat from the cats and/or turbos under the tank was causing the plastic to crack. Recently, there have been reports of dealer claims that a chemical reaction between aluminum heat exchangers and coolant damaged the tank and caused leaks.

Not sure which is the better theory. I replaced my tank preventatively. Maybe I will change the coolant preventatively. I think mine is original to my 2018 with 40k miles, but I bought as a CPO with 24k about 1.5 years ago and did not look at service records.

[Aronis]

I hate this thread. Moderator please delete it.

rrrrrrrrrr......come on BMW come up with a proper METAL tank. Jack asses.

Mike

[afo818]

I'm on my second tank installed 2k miles ago..
Already starting to melt at the seams again.
Getting 3rd one installed next week with the performance thermostat from turners see what happens.. :

[AHall]

Why would anyone expect anything different? Replacing the failed tank with the same tank? What is the expectation other than another failed tank after x months? I am not sure the tank is the issue or the solution since someone else posted information whatever the cause is damaged the charge air coolers. There seems to be a compatibility issue with the coolant and other components such as tank and/or charge air coolers and who knows what else. Is it the blue coolant which caused BMW to change to the green coolant? Maybe others who have had tank failures also have damaged charge air coolers they just don't know about yet.

[Egrunt]

Originally Posted by afo818

I'm on my second tank installed 2k miles ago..
Already starting to melt at the seams again.
Getting 3rd one installed next week with the performance thermostat from turners see what happens.. :

Interesting, having owned my 18 M5 since August of 2018 (4 years) I have not encountered this problem. My M5 is a weekend only car with just over 10k miles. What concerns me is that you have 2k miles on a new coolant tank and you are in need of a 3rd coolant tank. Knock on wood I have no issues with my coolant tank.

[pbonsalb]

Probably 90% or more of cars are fine and a quarter of them are 4 years old now. But the percentage of tanks failing seems likely to go up as the age and miles grow.

[AHall]

Originally Posted by Egrunt

Interesting, having owned my 18 M5 since August of 2018 (4 years) I have not encountered this problem. My M5 is a weekend only car with just over 10k miles. What concerns me is that you have 2k miles on a new coolant tank and you are in need of a 3rd coolant tank. Knock on wood I have no issues with my coolant tank.

What color is your coolant?

[Egrunt]

Originally Posted by AHall

What color is your coolant?

It is green.

[pbonsalb]

That is what I thought about the yellow level indicator making blue look green but I am no longer sure that is the case. The new BMW coolant definitely is green. I don’t know when it became available and began being installed from the factory. I’ll be partially changing it soon when I install the 90C thermostat so I will have some from my 2018 to sample.

[Aronis]

Originally Posted by pbonsalb

Probably 90% or more of cars are fine and a quarter of them are 4 years old now. But the percentage of tanks failing seems likely to go up as the age and miles grow.

Between the coolant tank leak and the LI Battery, the used car market for 5 year old M5's should be interesting.

I am ordering a new coolant tank today.

Mike

[ironbob]

Tried to check both coolant levels, main coolant cap was corroded on and took large channel locks to remove, was worried cap or neck would break, but got it off and lubed before replacing and cleaned. Small cap is frozen on and could not get off because of my worry about breaking, any thoughts on how to remove frozen small coolant cap without breaking?

[boost3dx]

Originally Posted by ironbob

Tried to check both coolant levels, main coolant cap was corroded on and took large channel locks to remove, was worried cap or neck would break, but got it off and lubed before replacing and cleaned. Small cap is frozen on and could not get off because of my worry about breaking, any thoughts on how to remove frozen small coolant cap without breaking?

could you get a strap wrench like this around it?

https://www.amazon.com/Oil-Filter-Wr...-1-spons&psc=1

[AHall]

I had an issue removing the main coolant tank. It appeared it may have not been installed straight when the BMW techs serviced the car during the annual oil change. No problem for the first 3/4 turn and then it got tight. I muscled through and now comes off and goes on without issue. It is a tight fit though.

[AHall]

Originally Posted by Aronis

Between the coolant tank leak and the LI Battery, the used car market for 5 year old M5's should be interesting.

I am ordering a new coolant tank today.

Mike

Mike can you confirm the sensor cannot be removed? I have seen the coolant tank sensors for sale by BMW as if it can be changed. When I look at the sensor and tank on my car it does not appear to be serviceable, but maybe you can see something different once you have it off the car.

[pbonsalb]

I have my old tank and it looks like the sensor is molded into the plastic tank. I have not fully explored whether the guts could be extracted from the molded plastic. Someone could measure the resistance of the sensor at a few points and try to compare to a removeable sensor for use in a custom tank. Probably BMW’s sensor is not unique to this car in terms of resistance, but I am not sure.

This link probably won’t work but realoem does not show a separate sensor. Looks like it is part of the tank.

https://www.realoem.com/bmw/enUS/sho...diagId=17_1194

F10 M5 tank has separate sensor. Obviously tank levels differ. Maybe it is just an in/off switch and that is all you need for a custom tank. If low, a ground is broken and a warning light goes off. Or maybe it is much more complicated and a signal goes to the ECU to pull timing, limit power, etc. Worth researching that.

[ironbob]

Thanks, got it off with my motorcycle oil filter wrench, fluid is a little low, not at min. Corrosion on both filler necks, lubed with WD40 silicone and both are easy now.

[Danny D]

geez - I'm due for an oil change on my 18, now at 38,000 KM.
I'm gonna check these coolant tanks best I can while at my friends shop.

[HerkHealer]

Does anyone know if the 2020+ M550's share the same Big Coolant tank as the M5? I'm guessing yes. My car has been in twice now with "low coolant" and coolant smell inside garage. They keep telling me its "normal" which I know is bullshit. The next time I get a low coolant warning I'm going to insist they swap the tank. My 2020 M550 has 13,300 miles.

They "Pressure Test the System" and say that rules out any cracks. Which I still say is bullshit. I can SMELL the coolant so its leaking out somewhere.

[AHall]

Originally Posted by pbonsalb

I have my old tank and it looks like the sensor is molded into the plastic tank. I have not fully explored whether the guts could be extracted from the molded plastic. Someone could measure the resistance of the sensor at a few points and try to compare to a removeable sensor for use in a custom tank. Probably BMW's sensor is not unique to this car in terms of resistance, but I am not sure.

This link probably won't work but realoem does not show a separate sensor. Looks like it is part of the tank.

https://www.realoem.com/bmw/enUS/sho...diagId=17_1194

F10 M5 tank has separate sensor. Obviously tank levels differ. Maybe it is just an in/off switch and that is all you need for a custom tank. If low, a ground is broken and a warning light goes off. Or maybe it is much more complicated and a signal goes to the ECU to pull timing, limit power, etc. Worth researching that.

I wonder if the sensor is pressed into the port? I think the chances are high the sensor is installed after the tank is molded and assembled/glued together. It may not be removable, but perhaps BMW sells the sensor separately.

[Aronis]

A good sheet metal guy can fabricate a tank out of stainless that would fit in the space.

Mike

[AHall]

I contacted a custom tank manufacturer who indicated they can make a tank out of aluminum based on a link I sent him showing the coolant tank. The problem is the sensor integration.