I'm having a nightmare!!! plase help

[fids]

Hiya, I'm having issues with my 1982 1.6 diesel. After overheating in the peak district, I got back home via the RAC. A suspected water pump/thermostat was diagnosed as a chemical head gasket test was carried out and proved ok, there is no signs of water in the oil, and the van runs fine with no smoking issues. However after a new water pump/ thermostat being fitted, the van runs fine and at a constant temperature until you give it a hill!! then it pressurises and overheats. I'm wondering if a u/s heat matrix could be the problem or wether it is the head gasket afterall. If anybody has had simular problems or any advise, you don't know how grateful i would be. Thanks Simon

[Aidan]

? is the system properly bled, heater matrix on, thermostat open, 2000rpm, rad bleed open, no bubbles, drive up and down hill, let cool, check top up tank, repeat till stable - now I once had a diesel van where the steel reinforcement from the front to back plastic pipe had broken up and a piece of it was lodged in the rubber pipe and acted as a flap intermitently blocking the return from the rad so it overheated but it also did in the headgasket - would get about 100 miles before it went again after cooling down and topping up - McGill chopped it up in the end

[rich broom]

poss blocked rad?

[fids]

Although the heater fan works, its never pumped warm air in and to be honest, the heater matrix pipes in the front of the cab have always been our source of warmth, just always got a bit warm in the summer. Do you think its worth bypassing the heater matrix to see wether there is a blockage there? The main thing that concerns me is its always run sweet as before and still does all but the overheating and this only started after it got hot in the peaks which is why i suspect head gasket, however the head gasket test proved negitive and although i understand these are not 100% acurate, there are no other signs pointing to the head gasket leaving me baffled!! The rad is only 12months old and we have a good flow around.

[Ian Hulley]

Not bled properly by the sound of it OR a leak.

Ian

[billy739]

the matrix will make no difference.

with the heater switched to 'cold ' vw designed the system to switch of the coolant flow , they would not of done this if it caused any sort of problem.

how long have you hadthe van? 1.6d & a hill would probably mean 1st / 2nd gear and 1/2 throttle so it can still accelerate meaning the engine isant working too hard.
or have you got foot to floor?