Have to refill coolant every 2 months??

[kngpen]

I have a new radiator and ever since Ive had to refill the radiator with water every 2 or so months. Is this normal? I have been refilling it with just water (not coolant) so maybe I should put more coolant...

Also my washer fluid refill has starting displaying on the dash, but it is already full and it only appears every other other other time I start my car (weird). Is there anyway I can disconnect this critical feature as the sensor is probably bad?

Also does BMW or independent mechanics charge to turn off the SRS light?

[Alan_525i]

I could make a joke about someone confusing the washer fluid and expansion tank, but I'll refrain.

Why was the radiator replaced? If the car overheated you might have blown the headgasket. An expansion tank worth of coolant every two months through the gasket would likely not appear in the oil. You could get the coolant tested for combustion gasses to see if this is the case. This is just one possibility.

The other possibility is that you have a pinhole leak somewhere. Very tough to track down. Just keep adding the coolant. The leak will grow. At somepoint you or your mechanic will find it.

[Jon K]

I could make a joke about someone confusing the washer fluid and expansion tank, but I'll refrain.

Why was the radiator replaced? If the car overheated you might have blown the headgasket. An expansion tank worth of coolant every two months through the gasket would likely not appear in the oil. You could get the coolant tested for combustion gasses to see if this is the case. This is just one possibility.

The other possibility is that you have a pinhole leak somewhere. Very tough to track down. Just keep adding the coolant. The leak will grow. At somepoint you or your mechanic will find it.


I disagree... an expansion tank is like 3/4 quarts of coolant. If that's going in your oil, you'd know it.

[Alan_525i]

every two months? thats every 2000+ miles for most people. I was losing it much quicker than that and it didn't show up in the oil for a long time. a blown head gasket doesn't have to end up in the oil anyway, can leak out to the outside of the engine and just evaporate.

That tank only holds a little over a pint of coolant. A pint is 471 mL. So even lets say you are losing 600 mL from the tank, that means you are losing less than 1/3 of a mL for every mile you drive. Surely that could be overlooked.

[Jon K]

every two months? thats every 2000+ miles for most people. I was losing it much quicker than that and it didn't show up in the oil for a long time. a blown head gasket doesn't have to end up in the oil anyway, can leak out to the outside of the engine and just evaporate.

That tank only holds a little over a pint of coolant. A pint is 471 mL. So even lets say you are losing 600 mL from the tank, that means you are losing less than 1/3 of a mL for every mile you drive. Surely that could be overlooked.


I dont lose any, so, anything over a teaspoon is too much :)

[genphreak]

I disagree... an expansion tank is like 3/4 quarts of coolant. If that's going in your oil, you'd know it.Surely it depends- going into a hot low pressure chamber a minor spray would be steam, followed and then encountering ignition+heat, then the exhaust stroke- I doubt the coolant could ever become liquid after it left the water jacket until it was at least down the exhaust or even vented to the atmosphere... although after driving the car normally for some weeks one might expect to see somewater in the oil from the cool-down periods where the cooling system was still pressurised and the engine shut-down, allowing a small amount of coolant to leak into the cylinder which might condense as the engine cools and end up in the bottom of the sump... however sump oil can boil off a fair bit of water through the EGR system during normal engine operation so it might well be 'keeping up' with the leak through this 'cycle'... after all; we are only talking about 20ml of coolant evaporating out the tailpipe if the car is used each day to effect what kngpen is describing :) GP

[winfred]

with a little over 120k miles on it theres a good chance that it still has the factory water pump and plastic thermostat housing, both of which are due for failure, washer fluid level errors are usually the float has turned sideways or upside down, the plug should point up, if that's not it the float has filled up and sunk or fallen off

[kngpen]

The previous radiator cracked and was shooting steam. It was replaced by the BMW center along with the water pump (bought a warranty for $2k and thats all they payed for was the water pump). Ever since Ive had the coolant dilemma. Maybe they reused the old cap and maybe thats letting out a little? Ill check with the floaty in the washer fluid as well.

[genphreak]

The previous radiator cracked and was shooting steam. It was replaced by the BMW center along with the water pump (bought a warranty for $2k and thats all they payed for was the water pump). Ever since Ive had the coolant dilemma. Maybe they reused the old cap and maybe thats letting out a little? Ill check with the floaty in the washer fluid as well. No signs of dried coolant around any of the hoses? That's the usual cause... intermittent minor leaks from tired hose connections or pinholes... I guess you've checked it all out though. No smell of ethylene glycol in the car? Dunno how good your Sense of smell is but I know that some people can't smell it (I can smell it a mile off) Could always be the heater core / plastic core pipes /o rings too...

[GS535i]

The similar 'mysterious' coolant loss on my car was tracked down to a leak on the back side of the expansion tank. There were no signs of coolant residue anywhere - a hot pressure test located the leak, for when cold, it held pressure for 12 hours.

[Beemr750]

I take it that the system has been bled allright?
What you can do is remove the radiator cap when cold,idle the engine,top off the radiator till it runs over,make shure the opening is covered all the time. Warm up to regular temp,the water will rise while it heats up but you should get NO bubbles ones the thermostat opens.Raise the RPMs once in a while and have the heater on to make sure the air is out.If bubbles continue coming out then you have a blown headgasket,which over pressures the system and drains it slowly.
Also after driving the car try to feel the radiator hose if its hard as a rock (more than normal,up to 28psi= the caps limit)you definitely have compression blowing into the system There is most likely no water going into cylinders yet because copmression is a lot higher tan the water press.

[kngpen]

Headgasket has recently been replaced, and problem has occured before and after replacement :).

[uscharalph]

My mysterious loss of coolant appears to be the heater core.