Coolant Loss Problem

[Alan_525i]

OK I rarely drive my car now. A trip to school maybe once a week, a trip to the grocery store and thats about it. Under 100 miles a week.

That being said, since the summer I had a coolant loss problem. Went through about a gallon of mixed coolant in three months.

Took the car to a new shop that comes highly recommended by everyone (I have great faith in them). They said the leak was from some corrosion on some of the hose fittings. All cleaned and pressure tested and all was good. So I'm happy. But then this weekend, 1 week after getting the car back, the expansion tank is empty. I'm wondering if it was just the system filling up a bit better after being filled or what? I tossed in more coolant and hopefully it sticks around.

The question is: If they pressure tested the system, could it still leak coolant? And from where? Radiator Cap?

[Jon K]

OK I rarely drive my car now. A trip to school maybe once a week, a trip to the grocery store and thats about it. Under 100 miles a week.

That being said, since the summer I had a coolant loss problem. Went through about a gallon of mixed coolant in three months.

Took the car to a new shop that comes highly recommended by everyone (I have great faith in them). They said the leak was from some corrosion on some of the hose fittings. All cleaned and pressure tested and all was good. So I'm happy. But then this weekend, 1 week after getting the car back, the expansion tank is empty. I'm wondering if it was just the system filling up a bit better after being filled or what? I tossed in more coolant and hopefully it sticks around.

The question is: If they pressure tested the system, could it still leak coolant? And from where? Radiator Cap?

Alan,

I too had a bad coolant loss this summer and i wasn't sure where it was coming from and i feared the worst... consumption, but as you know (or i think you do) it turned out that my water pump was leaking. apparently the O-ring around the water pump may have seen too many heatcycles because it no longer took up the space between the water pump and block, thus allowing coolant to squeeze past. this could be your problem, and is relatively cheap. about the radiator cap, if you had a coolant leak, it would be very very obvious because of the stain that the coolat leaves. i don't think the system needs to "fill up" so much, and if it did i don't think it would empty the entire expansion tank... but i guess time will tell.

[632 Regal]

just hold your breath, the expansion tank doesn't hold all that much coolant and if they just bled it and stuff it may just have burped the residual air out of the system.
Good luck bro!

[chamilun]

when pressure builds in this system, it begins to leak through cracks in the plastic expansion tank itself or in the hoses. the pressure test probably missed the expansion tank. so sitting in the driveway cold, coolant stays in. once driving at normal operating temperature, you get leaks. these leaks may eventually puddle if they are bad enough.

my recent fix was to put in Bars Leak stopper. worked like a charm.

to those who will say this is against the idea of keeping everything 'new' in some way, i only say my fix cost $3

[Jon K]

when pressure builds in this system, it begins to leak through cracks in the plastic expansion tank itself or in the hoses. the pressure test probably missed the expansion tank. so sitting in the driveway cold, coolant stays in. once driving at normal operating temperature, you get leaks. these leaks may eventually puddle if they are bad enough.

my recent fix was to put in Bars Leak stopper. worked like a charm.

to those who will say this is against the idea of keeping everything 'new' in some way, i only say my fix cost $3

I am a fan of $3 fixes too... but i remember hearing about horrid horrid problems with additives added to BMW coolant and such. Anything that has potential "oops" effect, i usually just avoid.

[chamilun]

I am a fan of $3 fixes too... but i remember hearing about horrid horrid problems with additives added to BMW coolant and such. Anything that has potential "oops" effect, i usually just avoid.

there seems to be many myths that surround BMWs for some reason. Never any direct examples though. i remember being intimidated before changing the oil the first time. ended up being the easiest oil change ever.

[632 Regal]

there seems to be many myths that surround BMWs for some reason. Never any direct examples though. i remember being intimidated before changing the oil the first time. ended up being the easiest oil change ever.

[andyman32]

Yeah, I mean, additives won't magically re-constitute a gasket, seal, o-ring or bushing. At best they gum up your whole system and plug up a crack for a few months. Then when the leak comes back, you end up replacing the entire system instead of just the problem part.

Look at it as a chance to learn more about your motor, to really fix it instead of just "trying something that might tide me over", and most of all, a great excuse to spend a day/weekend NOT mowing the lawn, taking out the garbage, raking leaves, doing take-home work, etc.!