Need some help understanding water flow and heater control valve. I have a 92 E150 Mark III conversion van that I am getting little or no heat. It does have both front and rear heat. I posted this question on one of the other forums before I knew about this one and did get one responce. They said that most likely I have two heater control valves. He has a 94 conversion van and he said he has two.

The coolant level is fine. Replaced radiator cap. Engine reaches normal temp, so thermostat seems to be fine. Temp control door seems to work okay. Friend said he thought it odd that when you take cap off when running at normal temp, the water bubbles up out of the radiator instead of flowing.

The one valve I have located is connected in the line to the top of the heater core and the hose is cold. The bottom hose to the heater core is hot. I'm trying to understand the flow of water. Since the bottom line is hot and is where the water flows into the core, then there would have to be a control valve in that line. Right or wrong?

The hose from the top of the heater core goes to a connector. Then there are two hoses that run from the connector. One goes to the heater control valve and then a hose from there goes to the back of the van. Anyone know what the other hose is far that runs from the connector?

Since the hose going into the core is hot and the one at the top coming out is cold, sounds like to me a plugged heater core. What do you think?

 

> Since the hose going into the core is hot and the
> one at the top coming out is cold,
> sounds like to me a plugged heater core.

Yes, both hoses should be fairly warm to the touch. If you run a 190+ thermostat, both hoses should be very hot. Then when you put on the heater, one hose (return) should be cooler, but, not cold. It should still feel hot enough so you can not keep your hand on it.

Sometimes when people flush cooling systems they do not reverse flush the system which clogs the heater core.

For $4, a few clamps, and a garden hose you can do it yourself. Maybe even save yourself some coin and hassle by not replacing the heater core.

Buy some plastic flushing Ts at a parts store. Install them in each line at the heater core. Attach your garden hose to the T connected to the line that is cold. Flush the water out of the T connected to the line that gets hot (leave the other hose end disconnected so you do not back flush junk into your cooling system).

When the water runs clear, flush the other way. Then back flush it one more time. Then install the caps on the plastic Ts, the hoses, and run the engine and see if you have an improvement.

BTW: If the core is plugged you will have a drastic reduction in water pressure and the water will sort of glug out. If the core is fairly free from restrictions the water will come out of the heater core like a tap.

DO NOT REMOVE THE HOSES FROM THE HEATER CORE UNLESS YOU ARE PREPARED TO REPLACE THE CORE WHEN YOU ARE DOING IT.

The reason being that if the core is plugged from rust, there is a good chance the pipes or their soldered welds will break under the force of you pushing and twisting. This will leak a fair amount of antifreeze and water into your van and make a mess.