Heater control valve

[wildwilly4x4]

That sounds like some good info! I have looked into those valves, and although the elec. looks to be the easiest, the reading I was doing on it seemed to show that it only had a duty cycle of 4-6 hours. Its not common for me to go 4-6 hours, but long trips that we go on (this is our family vehicle) could get into that time frame easily, with only stops for fuel. I kinda wonder if those short breaks would be long enough for the solenoid style to cool off and then be good for another 4-6 hours? As much as I hate vacuum stuff, that may be to most durable way to go. Thanks for the input.

[hatzie]

Originally Posted by wildwilly4x4

That sounds like some good info! I have looked into those valves, and although the elec. looks to be the easiest, the reading I was doing on it seemed to show that it only had a duty cycle of 4-6 hours. Its not common for me to go 4-6 hours, but long trips that we go on (this is our family vehicle) could get into that time frame easily, with only stops for fuel. I kinda wonder if those short breaks would be long enough for the solenoid style to cool off and then be good for another 4-6 hours? As much as I hate vacuum stuff, that may be to most durable way to go. Thanks for the input.

Never considered the vacuum solenoid duty cycle. The engine compartment heat may not do it any favors either.
If there's room... maybe you could mount the little monster inside the evaporator housing to cool it. Cut a biscuit out of the housing and mount the solenoid valve on a gasketed metal plate like the blower resistors. Pass the wires and vacuum lines through the mounting plate.

The other option is to use the AC vacuum line off the control head.

The AC control vacuum hoses are Nylon with soft ends. You can get nylon vacuum line on the HELP rack and any decent auto parts store will be able to get Tee, Straight, and 90° soft ends to slide over nylon vacuum hose.

The vacuum line diagrams are in the service manual.

[wildwilly4x4]

Sounds like a plan. I may order up some parts tonight for some experimentation! I'll keep up with the thread to show progress. I know idling with a/c in traffic makes this 8.1 get up in the 220+ temps fairly quick. Then it doesnt want to run good until i can either get the rpm up above 1500, or back at cruising speed. The heads must heat soak pretty bad on it, as you can feel it spark knock. The old stock 454 acted the same way. Mech fan just doesnt move enough air at idle. Even with two elec. fans it doesnt keep up. The full flow of hot h2o to the cold side of radiator is the only culprit i can come up with. All cooling system is in perfect condition, fan clutch, 4 row diesel sized radiator, fan shroud intact and hood shape.