1800: Heater Problem

[Tint]

Hello again folks,
Slowly working through the niggles of my newly aquired P1800 '68 B20.
Using heater control from hot to cold settings in the car whilst idling the air is always hot.
Temp pretty much stays at around a little over 160 on water temp gauge in the car (tis the old capillary guage). If left idling a little while does raise a little.
Round town stop start driving air is constantly hot.
Temp remains constantly a little over 160.
Motorway constant speeds hot air slowly gets colder until it is just like warm and temp goes down showing just a little under 160.
Any help or pointers would be much appreciated.
Thank you
Take care
Steve

[JP 1800]

Your heater valve is goosed. In the engine bay you will see a heater valve attached to the firewall with two small hoses attached. This valve will most likely be the culprit.. But before totally dismissing the valve make sure the cable controlling the valve is operational.

[Tint]

Thank you JP have eyeball'd it and checked cable which is good to go. Will price one up with a view to changing.

[Derek UK]

Also make sure that the flap in the heater box, the big one just above the transmission tunnel, is opening and closing properly via the control lever. These do have a sponge seal that can go bad and cause leaks but that really needs the whole heater to be removed to renew those.

[Tint]

Cheers Derek will check, Crikey the Heater Valves not far off £200 eeeek

[JP 1800]

One last check, I had an Amazon with a similar problem, disconnect the cable and push the lever on the valve end to see if it closes and prevents the flow of water into the heater matrix. The rubber seal inside the valve may have shrunk and a extra push will help it seal. The valve may also be bypassed in the engine bay.

[Ron Kwas]

Steve;

Check for mechanical action at valve as control is moved, as JP1800 has previously suggested! High sliding resistance in old Bowdon cable can cause sheath to slip from under clamps stopping transfer of control motion. Lube cable (graphite) and barb sheath-clamp like so to prevent:

Source: http://www.sw-em.com/checkchoke.htm (Same happens at chokes!)

Only after you assured that control input is actually getting to valve, yet it is still not closing flow to heat-exchanger may you even think about replacing it...

Good Hunting!

[Tint]

Cheers guys as always prompt and fab support. Will be sure to report how I get on.
Toodleloo
Steve

[SwallownAmazon]

Make sure the heater matrix isn't gummed up before you go to the expense of a new control valve. Back in the mists of time I had a Viva GT whose heater behaved in exactly the same way. Took the matrix out, reverse flow flushed it with a hose and all sorts of black crud came out. Worked a treat after that!

[Jocky66]

I used to have to reverse the pipes on my old escort (I think) heater matrix every few months. Back then I was much younger but not brave enough to pull heater out to flush it.