Possible coolant issue

[maxrob200]

The coolant bottle on my Jetta was faulty and I was losing a lot of coolant. Coolant light was coming on regularly at that ime. I would fill it up and the level would drop after a few days. Mechanic replaced the bottle and level has not dropped since

[pontiff]

I am going through the same sort of thing... car went through a reservoir of coolant (suspect water pump as its on the drop tray under it) but since filling up, has not lost a drop (now watch it lose it completely as is murphys law). I'm going to order a new water pump and will change it out none the less, but just saying.. its not out of the realms of possibility that it could lose coolant then stop

[brad]

My waterpump was leaking. When they pressure tested it, something (an o-ring I guess) was forced back into place and it stopped leaking for 9 months until I removed the pressure cap to add about 50ml of coolant and the "thing" moved again. Boy did it pour out after that.

My suggestion -
if the coolant level is around where it should be then don't remove the cap.

if you do have to top up, don't just go to the mid-point of the bubble - go about 20mm above that (overfil).

[piston broke]

The radiator on my GTi failed at around 42000kms, started with the coolant indicator activating, refilled it with the VW coolant and monitored it. I could see coolant residue around the engine bay but couldn't pin it down. I thought it may have been a hose leaking. After a couple more days coolant was down again. Ended up calling VW assist and having towed it to the closest dealer where they diagnosed the radiator. Replaced under warranty, the day before it ran out, usually these things happen the day after.