heater blowing hot but mostly cold!

[elnigel]

My interior heater, when set on full heat, warms up and then goes cold and wont come warm again!

there is no airlock or problem with the matrix, i distantly remember someone once saying there was a recall of mk2s and a valve was put in to stop high pressures, was wondering if this could be causing my probs, if so what is it, where is it and how can i check if its knackered?

Thanks guys!

[Veedubgt18v]

If you look under the bonnet at the back f the engine bay there are 2 water pipes coming out of the bulkhead, they SHOULD have the valves in them they are quite obvious, feel the pipes going into the bulkhead, they should be both hot, although one less than the other but not by much! if they are cold or there is a mega difference they the valves are prob blocked, its a good place to start anyway
ed

[modulater]

As the valves get old they restrict coolant flow resulting in poor heat output from the heater.

They were put there because the heater matrixes cant handle excessive pressure and let go.

A good fix is to fit the matrix from the MK3 as it is stronger and get rid of the valve completely.

[Blue MK2]

take the valve off!  

[modulater]

If you take the valve off and dont replace the Matrix with the later MK3 stronger versions you'll pop it at the first sign of increased system pressure.

Thats why VW put them there in the first place.

[GavG60]

change the valves mate, a darn sight easier than changing the matrix...

will cost you ?25 from GSF (or is it GFS / FGS..whatever!) takes five minutes to do.

[Veedubgt18v]

if that doesnt work then it could be the metal pipe running from the top of the head down the side of the engine to near the oil filter mount, sometimes gets blocked and causes porblems

[elnigel]

Cheers guys, will replace the valves and that metal pipe aswell as im currently tidying up the engine bay and it is mega rusty!

You have saved me from freezing my ass off every morning!!!!!

[JMallows]

I think all the recall was for is to stop the pipes bursting, and filling the passenger footwell with hot water!! Your car might not have been recalled, and if it was, it might not have gone in... Phone up your friendly VW garage, give them your regristration number and ask if you have any outstanding recalls. It will sya if it has been in, or not. If it does need it done, and hasn't had it done, then you can still get it done free.

Incidentally, it could be the thermostat?

Let me know how it goes with VW

[Blue MK2]

^ i asked Vw and they thought i was a nutter for even asking them