[SigForLife]

There is an issue (with a related bulletin, I understand) with a plug on the top of the engine not sealing. They just had to replace mine because I got a low coolant light and they were able to find coolant leaking in the plug area.

[paulyboy123]

Well looks like the warning came up again. Suspecting it is the cap to the main expansion tank now. Where can I get a replacement cap from. Does anyone have a link to one for sale by any chance?

[HerkHealer]

Originally Posted by paulyboy123

Well looks like the warning came up again. Suspecting it is the cap to the main expansion tank now. Where can I get a replacement cap from. Does anyone have a link to one for sale by any chance?

Call your dealership up. Parts Department. My dealer had the cap in stock. I was not happy it wasnt covered under warranty, even though its only $23.

[Eljeffrey13]

So since last summer i have had to top of coolant twice… about a bottle of water amount and no visible leaks but i did have residue on top of my tank and on my hood.. so i just brought it to dealership yesterday and they just informed me they ordered another tank

[vanos84]

Mine did this a few weeks back when it was cold as rip and I just had to add about 20 oz of distilled water to top off. No issues sense then.

[FatRear08]

I just had my expansion tank replaced last week as it developed hairline cracks in 3 places on the upper half as well as seepage around the middle seam. Same problem on my former F80. Why there are 2 pieces fused together is beyond me.

[HerkHealer]

Originally Posted by FatRear08

I just had my expansion tank replaced last week as it developed hairline cracks in 3 places on the upper half as well as seepage around the middle seam. Same problem on my former F80. Why there are 2 pieces fused together is beyond me.

I suspect my M550 upper tank is leaking, 2020. The dealership keeps telling me they pressure checked system and is OK. But i've had 2 low coolant warnings in less than 4 months, 1.000 miles. That is not OK with me.

[paulyboy123]

Originally Posted by FatRear08

I just had my expansion tank replaced last week as it developed hairline cracks in 3 places on the upper half as well as seepage around the middle seam. Same problem on my former F80. Why there are 2 pieces fused together is beyond me.

I had 2 F80s and both never had any coolant problems like this. This is the 4th time I had a warning within 1k miles. I don't even drive it a lot considering 1k miles in 5 months. I don't think I plan on keeping the car long too as I tend to switch cars every 9 months or so but still something thats a bit of a hassle. BMW provided me with a free container of coolant so I have been using that when needed.

[FatRear08]

To be losing that much coolant in a short amount of time and/or miles, there’s got to be a leak somewhere. If there’s residue anywhere, then it’s a no brainer and the dealer should be replacing the tank and cap at a minimum. Maybe try a different dealer and see if you get another result. Is it possible that the car burns off some coolant, especially if it’s driven how it’s intended? Probably, but not to your extent. In relation to this now that my tank has been replaced and all is good now, I’m going to have a 90 degree thermostat installed to keep things a bit cooler.

[paulyboy123]

Originally Posted by FatRear08

To be losing that much coolant in a short amount of time and/or miles, there's got to be a leak somewhere. If there's residue anywhere, then it's a no brainer and the dealer should be replacing the tank and cap at a minimum. Maybe try a different dealer and see if you get another result. Is it possible that the car burns off some coolant, especially if it's driven how it's intended? Probably, but not to your extent. In relation to this now that my tank has been replaced and all is good now, I'm going to have a 90 degree thermostat installed to keep things a bit cooler.

Exactly what I told the dealer. I said it doesn't sound normal that it loses coolant like this but the tech told me that's just how the engine is and runs hot so it burns coolant. They pressure tested and said all is well and no leak was found. I would like to buy a cap but don't know where to find one online if anyone has a link they can provide. I do not want to go out of the way to go to a dealership as it is like an hour plus drive.

[HerkHealer]

Originally Posted by paulyboy123

Exactly what I told the dealer. I said it doesn't sound normal that it loses coolant like this but the tech told me that's just how the engine is and runs hot so it burns coolant. They pressure tested and said all is well and no leak was found. I would like to buy a cap but don't know where to find one online if anyone has a link they can provide. I do not want to go out of the way to go to a dealership as it is like an hour plus drive.

https://www.amazon.com/Genuine-Coola...s%2C327&sr=8-3

[paulyboy123]

Originally Posted by HerkHealer

https://www.amazon.com/Genuine-Coola...327&sr=8-3

This is the same one for the main expansion tank?

[FatRear08]

Try this one. The Amazon cap appears to be an aftermarket product.
https://www.bmwpartsdirect.com/oem-p...ap-17117639021

[paulyboy123]

Originally Posted by HerkHealer

https://www.amazon.com/Genuine-Coola...327&sr=8-3

I just received this one. This doesn't look like it's meant for the M5

[Maverik259]

Originally Posted by FatRear08

To be losing that much coolant in a short amount of time and/or miles, there's got to be a leak somewhere. If there's residue anywhere, then it's a no brainer and the dealer should be replacing the tank and cap at a minimum. Maybe try a different dealer and see if you get another result. Is it possible that the car burns off some coolant, especially if it's driven how it's intended? Probably, but not to your extent. In relation to this now that my tank has been replaced and all is good now, I'm going to have a 90 degree thermostat installed to keep things a bit cooler.

Which Tstat you going with? Did this on my last AMG and had good results but I've heard the F90 is electronically regulated more than pressure like older cars?

[FatRear08]

Originally Posted by Maverik259

Which Tstat you going with? Did this on my last AMG and had good results but I've heard the F90 is electronically regulated more than pressure like older cars?

BMW part #11537586885-90C

[Maverik259]

Originally Posted by FatRear08

BMW part #11537586885-90C

Don't see a bmw part with that number.

Found a third part manufacturer with that number called bremmen

[pbonsalb]

I think BMW did lower the thermostat temp in 2020, but I did not find a BMW part. I think mine came from Uro but not sure of the actual manufacturer.

[pbonsalb]

When installing downpipes, I added heat tape to the underside of the upper metal heat shield over the turbos (there are 2 shields) and to the bottom of a new engine coolant tank. I have not done the intercooler coolant tank yet but that will be easy to do on the car. The engine coolant tank would be a pain to do cleanly while installed due to the contours of the tank bottom, but you could simply put a layer of fabric non adhesive heat barrier between the tank and the upper turbo heat shield as an easier and probably just as good method of heat reduction.

[AHall]

Originally Posted by pbonsalb

When installing downpipes, I added heat tape to the underside of the upper metal heat shield over the turbos (there are 2 shields) and to the bottom of a new engine coolant tank. I have not done the intercooler coolant tank yet but that will be easy to do on the car. The engine coolant tank would be a pain to do cleanly while installed due to the contours of the tank bottom, but you could simply put a layer of fabric non adhesive heat barrier between the tank and the upper turbo heat shield as an easier and probably just as good method of heat reduction.

Pbonsalb, I considered some sort of barrier around the tank as a preventative action. What are your thoughts on a material to use? My thoughts are some type of high temperature insulation placed on the sides of the tank adjacent to the engine.

[pbonsalb]

Any of the heat barriers should work, either a non adhesive sheet of the same stuff used in tape or a slightly thicker version like the stuff some use to insulate a transmission tunnel. I think the flexible stuff would be easier than a hard aluminized sheet that might crinkle up, but I would also stay away from non covered stuff like header wrap material or wool like insulation that will shed a lot of fiber under the hood. Just poke a couple of holes for the two tank legs and a slit for the bottom hose.

[vanmpower]

Over almost four years of ownership. I've topped up a good half-dozen times AND have had the system pressure-tested at the dealership twice. I just added ~750ml of water today. I'm calling the dealer again tomorrow. I have a LOT of residue around the cap (and below).

I will ask about the recall mentioned in this thread but notwithstanding, i feel the main reservoir cap is simply way too loose. I feel it could be much tighter before that "click" in which the arrows align.

I'll report back once the dealer checks things out...my warranty is gone in a month, hard to believe I've had the car for 4 (awesome) years.