Coolant related topic. Should have checked reservoir earlier

[NaweedMustafa]

While i was messing about with my intake system, i thought to myself "I have never opened up the coolant cap myself" and so i went ahead just to check out of curiosity (with a cold engine of course) and to my surprise, the measuring stick was pretty low... to the point where I thought I actually had no coolant at all. Is it bad that I've been running the car like this for a while? Didnt get any coolant dash warnings or notice any issues with the temp dial.

The garage did a coolant top up and flush back in 2023, which was roughly 20,000Km's ago so is it normal to see this much of a drop? I do occasionally check for leaks once in a while for oil and other fluids, I do notice some oil spots but never coolant. Any way I can try and determine if the coolant has somehow ended up in the combustion chamber during the past 2 years? (maybe I'm being paranoid here)

Will be heading out to get some G12 coolant. I read everywhere that G11 is recommended however, i do notice my coolant is red so i would assume its G12.

Do let me know of your advice/tips

 

[Zedebee]

It’s unlikely water is finding its way into the combustion chamber. You would notice a very steamy exhaust (often confused with white smoke) and extensive mayo under the filler cap (a little is quite normal for Z4s, particularly if driven short journeys).

More likely you have a crack in your expansion tank. You would normally notice a pool of fluid under the front left corner after a drive, although sometimes it just pools in the undertray, depending on where the crack is.

The crack/leak is often very difficult to see, just a superfine jet of water like a spider thread when the engine is hot. Best way to tell is to push a sheet of kitchen roll down the gap on each side of the expansion tank and see if it comes out wet. You’ll need the radiator cover off to do this (easy).

 

[Zedebee]

P.s. if the car hasn’t been overheating, you won’t have damaged it by running the coolant low.

 

[NaweedMustafa]

push a sheet of kitchen roll down the gap on each side of the expansion tank and see if it comes out wet.

hah, not a bad way to find out. I'll definitely do this, thanks!. Currently at 280,000 KM's so i need to start considering some preventive replacements with the usual suspects such as expansion tank, gaskets and etc.

Are the Z4's equipped with a sensor that triggers upon low coolant? I would have expected at least a yellow warning on the dash if it was well below the minimum threshold