Heater Question

[GolfDan]

This is confusing me!! When I have my heater on it at first blows nice and hot but then whenim in traffic it suddenly starts to blow cool after a couple of mins! Worried it may be my Head Gasket but im no echanic so havent really got a clue

[GTI EDITION (aka LTD)]

Does it have a bypass valve between the feed and return hoses for the heater ? If so then either your engine is overheating or just as likely that the valve is probably knackered .( I have replaced a few in the past with exactly the same symptoms as you are describing)
 The other problem is that VW do not supply these anymore and apparently say that you have to get two new hoses as they were originally .
This is all a bit puzzling as the valves were put in to protect the heater matrix if the engine over heated but for some reason best known to themselves it is no longer required

Hope this helps

[Organisys]

check the system for air locks like this:-

1) run engine with cap off coolant header tank
2) put heater on hot setting
3) with engine still running massage all coolant hoses (carefull hot!)
4) run engine until coolant nearly boils

You should see any air trapped in system begin bubbling up into header tank.

5) switch off engine, allow to cool for half hour or more
6) Top up coolant if required.

This may sort it, else remove matrix bypass valves as mentiioned above.
Cheers.

[Mr Blue]

just get rid of the valves there sh!t

[rubjonny]

The valves were fitted as a knee-jerk reaction from VW after an isolated case in the states where a matrix blew and scalded the passenger.  Rather than risking any more lawsuits a recall was issued for a set of bypass valves to make sure the pressure in the matrix doesn't get too high.
Many people have binned the valves without issue, in fact one bloke has had matrix failures WITH the valves fitted and 2 that are still running fine that never had them

If I were you I'd take the valves out and see how it goes, and if you still get no heat then its likely you'll need to replace the matrix!

[Organisys]

You can replace the matrix with a Mk3 golf item, which allegedly is stronger and less likely to leak.

[rubjonny]

Yeah the ones you get from VW/GSF etc are all stronger GSF items which don't need the bypass valves.

[GTI EDITION (aka LTD)]

45 minutes to replace matrix ..start to finish (I've done a lot of them)