Losing water, think its the pump

[Uruk Hai]

I'm losing water and it doesnt seem to be coming from any of the hoses (no dry antifreeze anywhere) and I'm pretty sure its not the matrix (no steaming up or damp carpets). Since having the car (91 8V almost 140K) I've replaced the rad, both plastic flanges on the head, both heater matrix hoses and the metal pipe. The cooling system doesnt appear to have too much pressure, the heater is toasty and the car runs at the same temp it has for the last 2 years without any trouble. As there doesnt appear to be any coolant on the garage floor I'm guessing that its leaking while the car is running above idle, my question is have I over looked anything that it may be and can the water pump be removed without first removing the PAS pump or do I have to follow the Haynes manual instructions and take the whole lot off ?
I've had coolant leaks before but spotted and sorted them out in no time, I want to be as sure as I can before I get my hands dirty.

Any help or advice realy appreciated 

[Conker]

I've got exactley the same problem with mine.

Here's a couple that aren't on your list... It could be the expansion tank cap venting when it shouldn't, or it could be (so i've read anyway) a poor mixture of coolant to water as the coolant allows water to go above boiling point without evaporating.

Mine is also overheating (only on long runs though), so I'm also replacing the thermostat and fan temp sensor.

[Uruk Hai]

I've just found the leak, its the plastic flange on the side of the head but I've replaced that once already ?

[Mr Blue]

They crack all the time. Worth changing. Not sure what model had the metal flange but I know some mk2's did

Could just be the 'O' ring that isnt sealing properly.

I used sealent and gasket paper on my new one.

[JC]

wish i could find the leak on mine

only leaks on a run

and the water blows the coolant everywhere 

[Uruk Hai]

What I cant understand is that I replaced one which was cracked and leaking but that couldnt have been more than about a year ago and now it appears as though the same thing has happened again  . Fortunatly I've just phoned my local stealer and they've got one in stock so I've paid for it and hope to pick it up later, I'm hoping a geniune one will be much better and last a lot longer than a pattern part 

P.S Mr Blue it was MK1's that had the metal part, VW should have made them from metal for the MK2's 

[Uruk Hai]

Thanks for the help, Rubjonny has explained all so I should be able to sort it out

Rubjonny you are the forum Leg-end and I salute you   

[Uruk Hai]

Hoping to fit this part tomorow and I was just wondering if there is a torque setting for the bolts or is it just a case of do um up tight enough to prevent any leaking, stupid question I know but I want the best chance of getting it right the first time. Cheers 

[rubjonny]

I just do em up 'tight'
i had a good leak, took me ages to find.  was one of the heater matrixc pipes at the bulkhead, id replaced the spring clips with jubilees and one wasnt quite tight enough!

[Uruk Hai]

I've just finished fitting the new flange and although the old one hadnt cracked it did look as though it was a bit out of shape or warped, the problem is I ran it up to temp and it seems as though there are still tiny wisps of steam coming from the same place ? I'm hoping its just what was left of the water that came out when I took the hose off being boiled off as the engine warmed up, if its not is there anything I can do ? I was wondering if I could fit a thicker O-ring or make a gasket to go round the outside of the O-ring to take some of the pressure off of it. I know I'm jumping the gun a bit and it may be O.K but I just dont want to have to keep topping it up with coolant because I cant cure such a simple problem, why didnt they make the MK2 ones from metal