haet in the car

[gteyes]

Inside the car heats up as normall untill the temp on the niddle goes between 1/4 and 1/2 ways then when the heat is turned to hot only cold air blows,
I know the thermostat is fine have checked the taps out side all is fine there. The only thing i can think of is blocking some of the rad to stop some of the air blowing through it and prevent the coolant cooling down so quick this problem only seems to happen on the open road
Has anyone else came across this before any help would be great

gteyes

[Leon R]

You are nearly there! Theres two valves called by-pass valves that you should see going into the bulkhead of the engine bay, assuming these are blocked, the heater matrix wont get the hot water.

If you do a search you will see these could be the fault and the solution is to remove them in place of straight copper pipes (22mm). However, VW added these valves as a recall as the Mk2's heater matrix's had a tendancy to let go, moreso, burn the passenger's legs by dumping hot coolant on them.

I wouldn't fit the copper pipes, either try a reverse flush to clean them to see if it makes things better or get some new ones.

[mattkh]

the heater matrix wont get the hot water.

Hi
How come he gets the heat in the beginning and it is very hot ?

[Leon R]

MattKH: You've made me doubt my own reading! I had read it as: ... Inside (on the cluster's temp guage) the car heats up as normal... as in from a cold start because it won't blow hot air from a cold cooling system anyway.

Gteyes, does the heater ever blow hot air then?

Normally if you are driving on the motorway and the temp guage is showing cold then it could be your stat that is faulty. I had the same symptoms, never had any hot air yet the temp would reach 1/2 way. On the motorway however the temp guage went right down so I changed the stat and all was ok plus the bonus of hot air again.

[rubjonny]

the hotter the coolant gets, the higher the pressure.  when the engine gets proper hot faulty bypass valves will cut the flow off too early and give you the symptoms described, as leon says, take them out and replace with copper pipe, if you get heat then you've fixed the problem, if not the issue lies elsewhere.

[Trigger1002]

Any chance of an update on this please? I'm having what sounds like the same problem with my 89 8v digi. If I start from cold the air will warm up as the car does. It gets to half way on temp guage and 96 on oil mfa where it will sit for a bit and pump out nice hot air. Then after a bit both temp guage and oil temp rises and the fan will blow out cold air. After a while the temps will come down and I'll get hot air again. Read a few posts now and looks like it could well be the bypass valves but would like a bit of feedback to reassure me I'm not barking up the wrong tree.....

[Witchwood]

I had exactly the same problem in my 1.8GL. You will need to either (a) replace the bypass valves or (b) substitute some lengths of 22mm copper pipe for the valves. Lovely and toasty after that job was done!

[hobbiniho]

also passengers with burnt legs 

[Trigger1002]

Just tracked new valves at gsf, as I need my legs for work I think I might pick them up instead of bypassing.  Thanks for your help and fingers crossed it does the trick.

[Dolly]

if u go to VW they done sell the valves now, you just get a pipe straight from engine to bulkhead, easy to change and imho better than a bit of copper piping.

i did it recently and also changed the matrix which was easier than expected. not really had it on the open road yet though as the G60 has a few issues that need ironing out first, but it did warm up very quick on tick over and the vents did blow hot for the first time since i bought her.