heater bypass valves

[moonraker]

Have had trouble with "madams" heater for a while now, took off the bypass valves and flushed out the matrix both ways, seems clear enough, put it back together and got REALLY hot air from vents

A while later she said the heater did not work again, tried vw for new valves  but they don't have any more.

Have took them off again and give them a real good and careful clean out, now there is no heat at all, could be just an air lock at the moment, so I will bleed the system.

Could someone describe the orientation of the valves and even better post a picture as well so I can be sure they are fitted correctly.

Is there a picture in the Haynes manual, not that I have one yet!!!

Many thanks Steve

[rubjonny]

The metal valve goes on the right hand (feed) tube and the black valve goes on the left (return) pipe.  The flow direction is cast onto the housing so easy to make sure they are on the right way round.
Most people suggest you just bin em altogether, they were only fitted by VW because of a single case in the states where the heater matrix burst.  The matrix is more likely to just start leaking than fail in this way, plus I've heard of a guy who had 2 matrixes fail which had the valves fitted, and 1 matrix is still going strong that has never had the valves fitted!

They are a bugger for airlocks though, best way is to run the car from cold with the cap off and squeeze all the pipes you can lay your hands on whilst reving the car to 2k untill the fan kicks in.  Make sure you keep the header tank topped up while you do this or air might get drawn back into the system.