Still loosing water on mk 2 GTI

[Alfie Moon]

I own a mk 2 Golf GTI Digifant 1990.  Owned her for almost 2 years but still having water problems.  Had the head gasket rebuilt and pressure checked just over 10,000 miles ago.  Have changed the radiator, expansion tank, alternator, thermostat, heater matrix, now fitted all the hoses with samco hoses.  Have removed the two thermostats from the hoses that lead into the heater matrix and replaced them with the copper piping.  Thinking that the problem could be with the water pump (Intermittent problem as sometimes car is fine and will loose no water).  If anyone has any ideas please let me know cheers.

[Simpson]

check for blue residue on all the pipe connections and exactly how much is it using?

[DarnPB]

Do away with those pathetic VW water hose clips and fit good quality jubilee items. You may be getting an intermittent leek from those that you have not noticed, especially if they are as old as the car. The bottom rad one is the favourite. That sorted out my problem anyway.

[rubjonny]

the VW clips are actually better than using jubilee clips, as they allow the hose & union to expand & contract as the engine changes temperature, and yet maintain the correct clamping pressure.  Although they are an utter nightmare to deal with, mole grips make things a little more bearable 

Edit: as for the original question, check the 2 plastic flanges on the front & side of the block those are common causes of coolant leaks.  Also replace the header tank cap for a new blue one, as the earlier ones had a problem with the seal/vent.
Last of all have a close look at your radiator for white crusty deposits!

[GT3 Turbo]

if i was dealing with it, i would get it up to temp, run it for quite a while on a high rpm and then turn the engine off, by this point your have lots of water pressure and will be easier to find the leak... you need to find where the leaks coming from before you can fix it....

[Alfie Moon]

 - Have now fitted the new water pump, new pulley (could not get the old one off), another new thermostat and housing unit.  All the clips are already changed to the jubilee clips.  Have changed both water flanges that come from the block.  Also have a blue expansion tank cap already.  Was sat in traffic the other day water temp as find about 1/4 of the way, oil temp was 94 - 96 when suddenly there was a bang and water starting pissing out everywhere.  The expansion tank cap had been forced out, due to the pressure ( blue tank cap now broken)  Have now put the original black cap back on and the car seems ok, but still getting a bit to much pressure and a mysterious water leak.  Put paper under the car in the garage at night but no sign of a leak. Any more ideas???

[rubjonny]

try a new genuine VW cap next

[mattkh]

Hi

Are you sure you have bled ALL the air out of the cooling system

[GT3 Turbo]

sounds like your engine is over pressurizing due to compressed air getting into the water system, most likely your head gasket could have a leak from (one or more) cylinders into the water system, hence the system is over pressurising.