Probably dropping an inch of coolant in a few hundred miles with no apparent leaks. Car has 70k miles.

Any possibility of this related to turbo cooling needs?

Or?

 

You check on top of the transmission housing for a small leak and pooling coolant? Sometimes they are hard to spot. If the engine was consuming coolant you can see and sometimes smell it from the exhaust at start up.

 

Unfortunately undetectable coolant leaks are associated with a bad head gasket, coolant leaking and burning off on the exhaust side of the head. Two things I would do, 1) Pressure test the system with a dye in the coolant look for leaks. 2) A Block test to determine if there are any exhaust gases in the cooling system. Good Luck.

 

An easy step one is to pull your oil filler cap and look inside for chocolate milk-looking goo. If you can't see any, smell it for the sweet sweet smell of sadness (aka coolant glycol).

 

Coolant clean, oil recently changed and is clean as well. Indy mechanic is proactive and would have called it out if it was milky. Oil seems fine to me. Mechanic said coolant loss isn't abnormal on hot running turbo cars, but I think it is losing more than normal.

 

That's the exact reason I would do a block test, only extreme cases will you see the milky oil cap. I would disagree with your Indy about coolant loss, these units are sealed and have a pressurized RECOVERY tank for excess coolant. If you're loosing coolant, it's leaking out or burning off somewhere. The only other thing I can think of is if your cooling system wasn't properly bled and the recovery tank doesn't have the exact amount of coolant. I have an R53, and this is a big issue with not having the Bleeding/Filling of the cooling system properly done. I don't know how much of an issue it is with your Mini, but that's all I got...

 

did he check the water pump? There’s a recall on it.

 

That was replaced under warranty last year.

 

Not sure if it is possible on this vehicle but in the past and on other vehicles I've had (that had no external coolant loses but using coolant and couldn't see/smell anything from tailpipe) with potential head gasket issue, one could see some bubbles in the over flow tank from the exhaust gas escaping into the cooling system (hence also the reason to "test" the coolant for presence of exhaust chemicals).

 

Not sure how turbo cooling needs play a role. My 2018 JCW doesn't use coolant.

A coolant leak almost always produces the unmistakable smell of anti-freeze. If you are not smelling anti-freeze -- and this includes with the engine running -- in case there is a head gasket leak and coolant is making it into one or more combustion chambers -- the leak could be from a bad cap if the cap is where the pressure relief valve is located. When hot and the engine shut off temperature can go up and pressure along with it and this can force water vapor out the cap.

With another car in a month's driving -- around 300 miles a week -- the coolant level would go down by nearly a gallon.

What I did was using distilled water I topped up the coolant tank. Not too full. But too low either. Then I made sure the threads on the tank were clean and the cap threads clean and then installed the cap and tightened it down. In some cases and this was one of them the cap required a bit more effort to tighten down than "normal". The cap want to be tight but do not over tightened or there is the risk the threads on the tank breaking.

I then started the engine and with the A/C off drove the car around town until the coolant got hot enough to trigger the radiator fans. With this car this was at 212F. Back home in the driveway I raised RPMs to a bit over 1K and held engine at this speed until the radiator fans came on again. I shut off the engine and placed a tent of foil over the coolant tank cap. In just a few minutes there was clear water condensed under the foil.

Replaced the cap and all was well for a good while.

With some cars -- and this was one -- the coolant tank can go bad. What happened is the tank developed a crack/split along the bottom mold seam. When the coolant was hot -- and now the cap was holding pressure -- the tank would expand and this opened up the split.

Catching a whiff of anti-freeze odor once in a while I suspected a leaking radiator. So I did the above hot pressure test and the radiators proved to be just fine. But the tank gushed hot coolant from its bottom. I let the car cool overnight then refilled the tank with distilled water and drove the car the couple of miles to the dealer. Once the tank was off it was clear the tank had been leaking for a good while. There was a nice crust of ugly green anti-freeze residue built up.

For suspected coolant leak in the chambers removing the plugs and looking for a "clean" one is the SOP. The anti-freeze cleans the plug.

Another test is to take a sample of oil and send it out for analysis. This checks for anti-freeze compounds and if any found this is a sign coolant is getting in the oil. The oil can get hot enough to boil the water out but the anti-freeze compounds remain behind.