Club 80-90 Forums

I've gradually seen a marked decrease in the temperature available from the heating system. I'm about to replace the antifreeze but wondered what (apart from faulty levers/valves) would cause this drop off? Van is well insulated but last thing I need is to be wearing a bobble hat this winter.

Water pump occasionally noisy. Operating temperature normal.

Blocked heater matrix?

On "older vehicles" whenever I change the anti freeze I always take the opportunity to flush the system. its amazing how much sludge can build up and as ninja said the heater matrix is great culprit for blockages as it usuallt pretty small bore tubing.

With then engine at normal operating temp I would also check the flow and return pipes from the engine to the rad to see if they are getting hot (at front as well as at back).

To flush i usually find a convenient place to disconnect pipes and then rig up something with a garden hose and just push water through till it runs nice and clear.

It could be your water pump isn't making enough pressure but go for the easy fixes first

MM

Leafs blocking vents/heater matrix partially blocked/water control valve not fully opening (not sure about the T25 setup) heater flaps not full closing so the air is not being 100% directed through the matrix.
Slow seizing blower motor (you can normally hear this) I wouldn't have thought the water pump is reponsible as the impellor is either driven or not although I have seen cases where the impellor comes loose or even breaks up (later plastic types) but rare.
Then there are air locks and head gasket failure which can both effect the heater blower..

Martin

My front heater fan does not work - seized!
However, when moving there is quite good heating, obviously nothing when stationary or really slow!
Therefore suspect your problem is hot water flow if you have good - cool - air flow when moving.
Have you tried the 'bong' method for refilling??
Best
Jon

Been a long while since I've used a bong Yes, I know the method you mean. I think a good clearout seems in order - backflush to make sure system is clean then refill and see if I get toasty toes.

Just a thought, my Dg tends to run cool unless going slow or up long hill or anything causing emgine to heat up, i.e. on motorway it seems to run at about 1/3 on temp gause- if yours is anything like this it might be that it has a thermostate rated at too low a temperature setting? Just a guess rather than informed by any technical knowledge. I suppose a strong mix of antifreeze might also predispose the temp to be cooler and vice versa.