Losing coolant...

[Matt UK]

I've got a 2004 VW Passat with the 1.9tdi engine with 160k on the clock.

I'm finding that I need to keep topping up the coolant - probably 500ml every few '000 miles. There is no sign that it's contaminating the oil (ie, no mayo on the filler cap).

Car runs well, performance / mpg normal, gets up to 90 deg temp and holds steady all day, every day.

Investigate further with a view to intervening before melt down, or just keep topping up?

[Matt UK]

Nope to both

[Matt UK]

GarrettMacD said:

I had exactly this issue with the wife's Volvo. It was down to a hairline crack in the expansion bottle. In my case it was the original bottle, and over 10 years old, so the join in the plastic had obviously degraded.

Might be the same on yours???

Good thought. the car is getting on a bit now and works for a living every day, so could be a likely candidate.

[Matt UK]

valiant said:

Are your carpets in the front damp at all?

(thinking matrix probs).

Nope, bone dry.

[Matt UK]

Prof Prolapse said:

You can get tiny cracks in hoses that only start to leak after it's good and hot (by which point it pretty much evaporates and you can't see it).

A friend of mine had some sort of UV dye and torch to inspect for the same problem. No idea where he got it from but it couldn't cost much.

Probably best check it out.

Will have a root around. Took all of the scuff plates and under-body cladding off fo a recent oil change / service and sisn't see the normal pink residue which can be a tell-tale sign.

Good thought though.