Heater not working 1988 740

[not hereplease]

The first two or three inches of the pipe from the engine block to the heater is hot, from then on its cold or colder. I have checked the heater unit and are sure its not blocked or airlocked, any thoughts on what is going on here.

 

[James Sweet]

The first two or three inches of the pipe from the engine block to the heater is hot, from then on its cold or colder. I have checked the heater unit and are sure its not blocked or airlocked, any thoughts on what is going on here.

You've got a blockage somewhere in the line, could be at the water pump, or anywhere else along the way. Does your heater control valve work?

 

[not hereplease]

The heater worked for a short time yesterday.
I stopped at a service stationthen when restarting the heater was not working again. I have blown through the heater so cant understand what's happening

 

[Peter Milnes]

Quite possible that the hose has collapsed internally which will stop water movement.

Cheers, Peter.

The first two or three inches of the pipe from the engine block to the heater is hot, from then on its cold or colder. I have checked the heater unit and are sure its not blocked or airlocked, any thoughts on what is going on here.