I’ve a mk3 2.0 tdi. Recently it developed a coolant leak. I bought the car in 2013 for a different job when I was doing a high mileage but my circumstances changed and I do a lot less now, so 33000 miles on the clock. 

Anyway the leak isn’t obvious. It appeared to be the reservoir that was leaking so that was replaced (don’t think the cap was replaced) and no issue for a week or so. Again it’s started leaking. It seems to be intermittent, normal engine temperature and seems to happen if the fan has been running after the engine is off. 

Looks full there but that was just after I stopped. Was down pretty much at the minimum when it cooled down. 

Very possibly the waterpump. See this sticky:

 

Or take a look at this post:

 

Ah thanks. I should have clarified. The car was in the garage and the mechanic said the water pump was fine. He initially thought it was going to be the water pump. The only leak appeared to be around the reservoir at the “equator”. 

I’ve not had any temperature spikes or anything. It randomly just starts to lose coolant. 

Bearing in mind the splatters around the bottle, as well as it looking like the leak came from above, (the puddle in the engine mount is a clue) I would suggest changing the coolant bottle lid too. There is a pressure release valve in it.

 

also check the pipes into the bottle.

 

if it was the water pump, you would expect engine temperature to shoot up in use.

 

also iirc there are notes in the manual for how to check coolant level and I am not sure it’s at dead cold. (Obviously not at hot so don’t open the coolant tank when hot as it’s extremely dangerous to do so)

Edited 2 August, 20196 yr by cheezemonkhai

Pressure test the cooling system and cap to check for leaks.

 

 

Well, I was thinking of the expansion bottle cap being the fault too.