In my pre-MINI life, I was a car killer. So I guess I know what I need to do. But I've already written the rest of this, so here goes. I was running hot tonight (fortunately I needed and had my defrosters on). I checked and my coolant reservoir cap was gone.

I don't know how long it's been gone. Now that I think about it, I heard a "pop" when shutting her down the other day when idling (again, running hot). And I've driven a fair bit since then. Obviously I should have checked the coolant right then. I turned on the blowers and that cooled things down. Yes, I'm ashamed I didn't look right into it.

The level Tonight (when it occurred to me to check) was just under min. I poured some filtered water in to bring it just above min. OK, I also "smithed" an aluminum cap for it, and tightened it shut.

So now I realize I need help. What do I do? I've been driving like this for days. I've shocked that it's still running without fail. And surprised now that I realize what that "pop" was, that it has any fluid in it at all.

I guess I'd like to drive it in to my mechanic in the morning, but I don't think anybody's going to agree with that. I'm so spoiled with this little car working so well that I overlook things like keeping an eye on the fluids and of course I'll know better next time. Having had the thermostat replaced while under warranty, naturally I thought my coolant issues were gone for good.

Mea Culpa. I guess I should just get another ride into town tomorrow and pick up some coolant from my mechanic or the dealership? And what about the blown cap? Can I replace the reservoir unit myself? Thanks much.

And I hope you have a great ride.

 

I left her in the barn this morning. Waiting to hear from my mechanic.
I was tempted to crank the engine to watch the reservoir, but left it alone.

If the radiator is spent or worse, should I be hearing bells or whistles (or worse)? Thanks in advance for your kind consideration.

 

Sounds like the cap was just not on propperly.....and popped off from the pressure...
Filtered water is as bad as tap.....use distilled water....filtered water can still have a very high mineral content.
As for coolant....add more of the same type you are using. If it is blue....it is bmw/mini coolant....a somewhat unique hybird chemically.....do not add "universal" coolant....if the level was ok....you might just need yo check the concertration/ freeze protection level, add a new cap and be good....but if the level was very low, a bleed might be needed to prevent a possible overheating from a trapped airbubble.

 

my guess too is that the cap was simply not on tight. Get a new cap and top things off is all I'd do for now.

Comment about need for a bleed is right on too, and if you DO still see high temps it is the first thing I'd try next.

I'm not sure why you would need a new resiv' but on an S replacing one takes about 10 minutes. One bolt and two hoses as I recall. I've replaced mine and a couple for others. A little different on a justa but not much more difficult so far as I can tell. Got the wrong bottle once so know what it looks like, but have only actually changed S models

As I recall the new bottle did not come with a cap ... that is sold sep' so check. If it did, I'd expect to have several caps in my left over parts box.

 

OK. Thanks ZippyNH and Capt bj.

I have no coolant (and don't know how to bleed). Should I have it towed (in case of airbubble), or, should I go to the dealership while out today, pick up some fluid and a cap (and distilled water), and add those / see how it does?

The stem the cap goes on may be damaged. I recall that the cap had a flip top (?). Will a new cap "snap" right on?

Thanks again for your advice!!

 

The cap allows a higher boiling point so the car doesn't overheat. Given the winter weather, that hasn't been an issue for you. I can't see any rational reason to do anything other than top it up (with distilled) put a new cap on it. You will not have done any damage to the radiator. The only possible issue would be ingestion of dirt/crud, so you could flush it if that makes you feel better, but that would be merely a precaution.

Now had your brake fluid cap been off - you'd definitely need a fluid flush, but coolant doesn't have the same issues.

edit: No need to tow it. The cap is a screw top, not flip top.

 

I'm feeling better now. Thanks Eric!

 

Had a great visit to MOB last night. Saw the new models, bought the $5 part. Fixed it in five minutes. Thanks for your assistance, everyone.