losing water and don't know where

[Apache]

E36 B3 3.2, keeps losing water but there is no evidence of it anywhere, but a colleague has a theory. I'm overfilling it, when the warning comes on he suggests I bleed the air of a little allowing the level to rise enough to put out the warning light and it'll be fine after that...this is from his experience of a diesel Golf, so I'm gonna give it a try. If anyone knows of similar E36 foibles please share

[E30M3SE]

Have you checked your carpets, the thick foam backing can store quite a bit of water.

How much water are you actually losing?

[Apache]

hard to say, the light comes on every 2 or 3 days and the water has dropped down to the bottom of the expansion tank, it's not leaking into the car at all

[miniman]

My E34 had a tiny, **tiny** leak from somewhere around the thermostat gasket which was hardly visible but drained the expansion tank over the course of a week or so.

Squeeze the hose running up to the stat and look for a tiny trickle running down the underside of it.

[E30M3SE]

So, at least half litre, guessing that is max to min although it maybe more, in 2-3 days with no visible signs......... I'd be doing a block test just to rule out any HG issue, but before you do that ensure the pressure cap is sealing correctly.

Edited by E30M3SE on Thursday 12th April 20:42

[Allanv]

I had an E46 that did the same and it would only loose water after I stopped, turned out to be a leak in the expantion tank.

Very small hole / crack but enough to loose water in order to set off the alarm bells.
Maybe worth a look.

[tgr]

The car will be 15 years old. Any evidence of cooling system replacement? If not, as others have said, may well be worth radiator/expansion tank/water pump renewal

[Huff]

Another thing to check is the seal/o-ring on the filler cap itself. If even slightly perished these can weep vapour when the system is under pressure (as is normal when a car up to temp) with nothing to show... this is true for any car BTW, not just the OP's

[Apache]

thanks guys will do