Water Loss

[matty 0]

I have a 1995 VR6 Golf which looses water sometimes. No water in oil, coolant very clean and it can do long runs and sit in traffic with no problems.

Then - and it seems to be when stopped hot, it leaks from the plastic bottle sometimes.

Found a dud fuse to the auxilliary electric pump which does work OK when fed from a battery, though it only takes about 0.5 amps running which seems a bit low for a pump.

Since replacing the fuse which has not blown since, water seems OK so perhaps this was the problem?

The After Run Cooling system however never seems to come on and I thought this might be causing over pressure after turning off a hot engine.

So have also replaced the Temp Gague/After Run sensor having checked by shorting appropriate pins on the sensor connector that the fans and Auxillary electric pump operate OK. But the after run system never operates, so perhaps this boils the water in the head and causes overpressure after running.

Have checked the after run sensors (at higher than boiling point) and both the old one and new one work fine in the kitchen!!

Any ideas why my After Run Cooling does not seem to work- when I believe it should do something in the present heat wave!! Obviously basically the sensor switch is not making, which could be if there was not enough pressure in the system to stop boiling at above 105 degrees C when the switch is designed to make. However the water pipes seem under pretty high pressure so I don't think this is the problem.

PS have also earlier changed the pressure cap for a blue one to no effect.

Engine does not overheat running and radiator fan runs up from radiator switch OK - could there be some strange fault with the thermostat which seems to be doing its job with no flow through the rad. from cold and later the rad pipes hot and the correct reading on the temerature gague.

Any ideas please - sorry for the long ramble.

Matty

[VR6_Absy 0]

Blimey, uv had a good go

I had similar for a while and like u replaced Header Tank Cap I even had it pressure tested everything was fine. However when i changed my thermostat it sorted it.

It's worth a try

[matty 0]

Thanks - For the first time ever since in the few weeks I have owned the car, the "after run cooling" system fired up yesterday - sod's law after I had started the string !!!

Also I do not seem to be losing water now, though the car has not had much use.

The new blue rad cap I bought is I believe faulty, because it was with this on that water was blown in quantity out of the plastic tank and I now have the old black one back on and it seems OK with lots of pressure in the system.

Perhaps it was just an air lock (how did the air get in?)

and when I changed the sensor and bled the system properly it fixed it - or maybe replacing the blown 5Amp fuse for the auxilliary water pump has has some effect - time will tell!!

Bloody modern cars are too complicated - I should have stuck to old classics which are easy to understand, but I love the performance and comfort of the Golf VR6 in comparison.

If problems persist will change the thermostat though it seems to be working OK.

I apologise for my academic views but am afraid I am an ex electronics design/research engineer and have been brought up to really understand why things do or do not work - it costs a fortune if you put a product on the market with design problems left in.