Header Tank Leaking - help !!!

At 1st I thought it was the pipe from the header tank to the radiator (return pipe I think) but after replacing that there is still water accumulating on the ridge of the header tank after a run - Ive had a few MK1 GTI's and I have never heard of a header tank leaking but it really does seem that its leaking from where the header tank in effect fits together - anyone had same problem???

Cheers
Mal

Yep - it was a blown head gasket.

See whether the coolant outlet from the top of the head is blown up like a balloon.

If not - it might just be the coolant sensor that screws into the header tank. Check to see whether this has a crack in it - it will probably be hidden between the threads.

If this is the case the water will come welling up from around the sensor and flow down the outside.

Even so though - a blown head gasket will push the water out even quicker.


Ali Cabrio
PS - I'm replacing my head gasket cos of this at the moment. So far so good, but if you get someone else to do it the cost is a tad on the large side ?400+

I dont think….or should I say hope it isnt the head gasket!!!

I'll check the top coolant outlet but from memory I think everything looks OK….will also check the coolant sensor on the header tank for cracks.

Im talking very little water after a 20 mile run…..there is no water in the oil……if it turns out to be the head gasket I can handle that anyways without paying out for someone else to do it so thats one bonus I suppose !

Cheers for the response
Mal

Could also be a leaky water pump.

Park it somewhere where you can spot the wet patch underneath.

I so hoped that mine was just a leaky water pump - but then gobbets of grease appeared in the coolant header tank - and it started to smell of petrol  :roll:

Ali

How would the water pump make the header tank leak?

Its garaged and I have never seen any water on the floor after a run…..there is no grease in the header tank

I'll check the sensor and then probably change the header tank and refresh all the coolant and see what happens then …..fingers crossed !!!

Cheers
Mal

Had same problem ages ago, renewed the pressure cap cured it.

When it happened again recently I replaced pressure cap, then the header tank (with new), but it turned out to be the head gasket this time.

I've had a problem with a header tank leaking. After 15 years and 70k miles of hardly ever topping up with water, I was suddenly having to top up weekly. Eventually traced it to the header tank which had a pin hole in the side. Never saw any standing water but found it only by chance when I was doing something else under the bonnet and was using an inspection lamp, noticed a vey fine jet of water comming out of the tank but only with the engine hot and pressure in the system which very quickly bled away when the engine was switched off. New header tank cured it.
Don't fear the worst, it could well be the header tank

Also check if you have the original black rad cap, which has two circular fittings on the inside - if so, change it for the later design (blue) one from VAG or GSF-type places, as it has a different design which won't leak.

When the original one gets to a certain age it starts leaking, which is why they changed the design…

This may or may not be related to your leak, which may well be the header tank.

Cheers guys - Im gonna try the coolant sensor, the header tank cap and then the header tank itself and hope that I dont have to take the head off !!!

Thanks again
Mal

What was I on suggesting the water pump?

 ops:

Apologies Malc - completely in world of my own on that one. Good luck with sorting the leak out.

Ali

AliCabrio said

What was I on suggesting the water pump?

 ops:

Apologies Malc - completely in world of my own on that one. Good luck with sorting the leak out.

Ali

At least you weren't suggesting it to a Beetle owner!  :wink:   :mrgreen:

type17 - Ive located the problem and its just the header tank cap - it has the blue one on but its leaking after a good run - if I order from VAG then will that be the blue one then?

Cheers
Mal

MalC said

type17 - Ive located the problem and its just the header tank cap - it has the blue one on but its leaking after a good run - if I order from VAG then will that be the blue one then?

Cheers
Mal

It could be three things:

1. Faulty blue cap - although a better design than the old black one, it could be nearly 10 years old (I Bought one in '97, so it could be at least that old)

2. Too much coolant - if you overfill the system, it will leak out of the cap

3. Failing (but not totally failed) head gasket - causing a little leakage.

Actions:

1. Check coolant level mark to ensure that you aren't overfilling. If not, then
2. Replace blue cap with new one. If it still leaks, then
3. Get a garage to do the test to see are there exhaust fumes in the coolant (they take a coolant sample and mix it with a special chemical, and if it changes colour, the head gasket is allowing exhaust fumes into the coolant)