I have a 1966 Ford F100 I have been working on and the heater does not heat, although the fan motor works fine. I have put in a new heater core, and that did not solve the problem. I removed the bypass hose and notice no water coming from the engine after a 10 minute warm-up. Wondering if I have a water pump problem (or start there next) or another issue. Any ideas on how or where to trouble shoot next?

 

Didn't they also have a valve that you open, or close to get the coolant to go to the heater? That may not be working.

 

There is, looks like a butterfly valve, and I have tried it open and closed and latterly no water is coming through. So I was think there might be a water pump issue or a clog in the line possibly since I have driven the truck a good deal and it has not overheated, although it has been rather cold here in Atlanta.

 

Welcome to FTE

1965/66 F100/250: There are TWO different types of fresh air heaters.

The Economy version has a manually operated heater water shut-off valve (C5TZ-18495-A) that is spliced into the inlet to heater core heater hose.

The Deluxe version has two cables mounted to a bracket that is located under the dash...to the right of the steering column.

One of these cables connects to the heater water valve (C3UZ-18495-A), it too splices into the inlet to heater core heater hose.

This valve is notorious for getting stuck in the open or closed position.

C5TZ-18495-A .. Shut-Off Valve is obsolete, but can be found NOS / C3UZ-18495-A .. Cable Controlled Heater Water Valve (Motorcraft YG-133) is available from Ford.

 

I have the former - a spliced version, which is the butterfly valve. It has been open but still no water is getting through. Any ideas why not?


Thanks.

 

Both the shut-off valve and the cable controlled water valve are spliced into the inlet to heater core heater hose.

This is not a 'Mickey Mouse' method, even though it make look that way. It's the only way that these two valves can be installed.

Problems: The heater core is plugged up, and/or the heater hose is kinked.

 

Tuntavern1775 Welcome to and the Slicks Forum.

Hot water has to circulate throught the heater core for it to work. It sounds like this is not occuring. The valve that has been mentioned sounds like it is closed.

Do you have access to a piece of 1/2" copper or pvc water pipe a couple-three inches long or longer? Pull the valve out and insert the pipe in it's place, with hose clamps. This should allow full flow at that point. This will allow you to further test the flowing of the water.

Drive the truck a bit then raise the hood and feel the hose for warmth, if one side is warm and the other cold there is a blockage, if both are warm there should be some heat in the cab.

You can also have cold air coming in the cab that can overcome the warm air from the heater. I blocked off & removed the large hose going to the pasenger side fender area because of that.

Something to chew on.


John

 

I would start at the intake manifold, remove the heater hose from the outlet fitting and see if water is flowing there. I've seen the 90 degree fittings plug up.

 

Agree w/ Jim's suggestion; however, and not sure, but just in case water circulating to the heater box would not flow until the thermostat is open, my suggestion would be to loosen the clamps at the pump beforehand, run the engine and once the thermostat has opened then remove each hose at the pump and reattach quickly one at a time, should be able to confirm it water is flowing and which side of the pump is the inlet/outlet??

 

I am going to also replace the thermostat as I have not temp readings now...and so the thermostat may not be allowing water to flow through the bypass hose. Doing that this weekend.

 

The rubber bypass hose (352) is located between the water pump and the intake manifold. Do not try to replace the hose without taking the water pump off first.

The water pump has a connector made as part of it for the hose, but there's a 5/8" I.D. steel tube (it's a "press fit") that inserts into the manifold to retain the other end of the hose.

Try removing the hose without removing the water pump, the tube will break off. But, it's probably rusty be now, so you may have to replace it regardless.

Auto parts stores sell a universal 5/8" I.D. steel tube, but it has to be "cut to fit."

 

Water coming out of the intake manifold has nothing to do with the thermostat, the outlet is before the thermostat. As the water heats it should flow from the manifold to the heater core long before thermostat opens. From the heater core it flows back into the inlet on the pump.

 

did you remove the plastic plugs shoved in the ends of the NEW heater core before connecting the hoses ?

 

Excellent point, a man with his thinking cap on. Sometimes we miss the simple things.

 

Don't know if you were peeping over here in NC but the water pipe suggestion that I offered is 5/8" OD pipe. If I hadn't already done this I wopuld not have recommended it.


John