E32 losing coolant.

[LHD]

Chaps,

My E32 735iSE has started to develop a liking for coolant, around half an inch drop in week at the expansion bottle.

I've had the system pressure tested and no leaks, replaced the expansion tank cap and still it's losing it.

I've also had the head tested, oil is clean and no emulsification around the filler cap, also the carpets are dry so it's not leaking around the heater matrix.

Where the hell is it going?

Edited by LHD on Monday 21st December 15:47

[E21_Ross]

it might be a very similar system as is on my E21, although mine get's poured straight into the radiator when filling up. right near the filler cap there is an overflow pipe, when the cooling system is under pressure coolant seems to rise up and come down this pipe; i'd say my E21 gets through about 100ml of coolant every 250-300 miles or so at a guess. if you're head gasket is fine, heater etc still works, and the car isn't over heating, i wouldn't worry too much about it. you might find, if you don't top it up, and leave it perhaps half way between min and max (although my car doesn't have marks), it might stop losing the coolant. if i leave mine about 1.5 inches from the bottom of the filler cap, the coolant doesn't seem to drop, but the lower amount of coolant means it can run warm in traffic (but it never gets anywhere near past 3/4 mark, let alone into the red), but i just keep topping it up anyway

just keep an eye on your coolant temp, level, 'mayo' on the filler (hopefully none!!), and you will be fine. check for any drops of water under the car after you park it too, that's how i found mine comes through the over flow pipe, if you can see drops, open the bonnet and see where it's dropping in relation to parts in the area.

hope all goes ok!

Edited by E21_Ross on Monday 21st December 16:16