Hello,I'm sorry you haven't received an answer sooner, I hope I can be of assistance.
Does the van have air conditioning? Does the heater not change at all for example go lukewarm? Does the temperature gauge work as normal?
Let me know and I'll reply as soon as I'm able to.
No air conditioning. No change in temperature either. The gauge works as should.
as the vehicle doesn't have air conditioning then the temperature flap inside the heater box is controlled by a cable, although you say that you can hear the air flow change you need to make sure the cable is moving the lever to alter the temperature flap.
Also you mention the heater hoses check that both of these are as hot as the rest of the coolant hoses.This engine has 2 thermostats, as well as the main thermostat there is a small thermostat in the end of the coolant distribution manifold that sits just below the inlet manifold, it may be worth replacing this as if this fails the cooling system doesn't operate correctly.
Start with these points, let me know if I can assist further and I'll reply as soon as I'm able to.
The flap control is working fine, the other thermostat is working fine i've checked with a kettle but also put another one in from another transit which was working fine but still no heat. Im completely stumped!
if the flap is moving inside the heater box and both heater pipes are the same temperature as the rest of the cooling system but no heat is coming from the heater then this would indicate a blocked heater matrix. I know you blew the heater through with compressed air but the pressure from an air line is a lot more than any pressure in the cooling system. You could try removing and clamping 1 heater hose and see if there is a good coolant flow through the heater matrix.
Let me know if I can assist further.
Hi, the matrix isnt blocked as we got water to flow through fine. Its as if the water is not being pressurised enough, the heater hoses to the matrix do not seem hot enough to provide heat maybe due to a lack of pressure not forcing the hot water to the matrix?
the only thing that circulates water through the matrix is the water pump, the pressure in the cooling system is generated when the coolant heats up, this doesn't force coolant through the matrix. You mention a new water pump, check that the impeller hasn't come adrift from the pump shaft, as I said earlier the water pump is the only component that circulates coolant.