Coolant leak on 99 Passat???

Does it have an oil cooler leak? Some are water cooled and produce odd leaks/losses that are hard to spot.

I fear it could be your heater matrix! I had this on my Corrado , coolant loss without any evidence, only difference to on the mk2 golfs was the windows didnt stea up, after selling the corrado 2 months later the chap told me the marix needed replacing.

I can ask the mechanic to check for that, is it the case that you should see some mayonaise coloured gunk at the oil filler cap??

Oh gawd!!! I hope not. I sense I may have been sold a lemon in that he must have known that this car goes through 1.5 litres of coolant every 4 days.

But if it is the matrix should I not smell a sweet/glycol smell through the air vents and perhaps see a leak on the front carpets??

Cheers

You should see signs of where it has come out - pinkish/white deposits. Get it up to temp and look for leaks everywhere - it may only do it under working pressure. Check exhaust for excess steam - shouldn't see much if any, but if it's significant, could be head gasket trouble. It's obviously coming out somewhere - hope it's a simple problem.

A friend of mine had the same problem on his Passat 4motion, which turned out to be a fooked headgasget.

Depends, I had a leaking matrix on my Audi for about 6 months before I noticed it, prompted by lifting the mat in the drivers footwell and realising where all the leaking coolant had gone . . . car was a little more steamy in the cold than usual, but nothing you'd really notice as the rubber mats were stopping evapouration . . . the matrix was leaking at the bottom so very little ever made it onto the matrix itself hence lack of smell . . .

Depending on the plumbing in the car you could bypass the matrix for a few days and see if the leak stops . . .

Fd

My Corrado needed topping up every 120miles or so, in fairness to the seller they may not have known either as you mention the dealers looked at it twice without success.

I didn't have any of the usual symptoms compared to the mk2 Golf (eg windows steam up real bad, wet carpets). Apart from excessive coolant loss there was no way I could tell, my mate had a head gasket tester and applied this to the car and it showed clear, the car run fine, the only other symptom I noticed was that the heater was working nicely until you came to a halt then it would only blow luke warm, when I 1st had the car only the brave would put the heater on full heat as it was hot!

IIRC the heater matrix replacement is the most time consuming job on a VW :-(

Suggest you drop the belly pan & see if you can see anything on the upper side of it (to point where the leak might be coming from) or generally from underneath. The G12 turns into a pink crusty substance when it leaks out (kind of like Pepto Bismol!) & if you can see any signs of that then you are in with a shout.

I just replaced the radiator on my 98 1.8T - found a tell-tale stain at the joint of the matrix & the header tank when I took it out to change the cambelt. Was pretty much impossible to see without removing it. There was a small stain on the inside of the belly pan at the front which is what steered me towards it. The leak was at the opposite end from where the hoses plug into the rad.

Other options are the oil cooler, heater matrix or maybe a head gasket but I think HG failures are pretty rare. Hopefully it will be something simple & cheap to fix.

I.

If you get a leak when the engine is hot and pressurised, it doesn't take much to dry up the water as it leaks out - it's almost at boiling point anyway.