Installed a heater valve today....

[robthebuilder]

99 Super Duty 7.3- no factory heater valve.

So I went to Carquest, bought one, hooked it up, worked fine when I first started the truck to check for leaks. After I drove around for a while and got home, I realized it was allowing some water into the heater core, while it was in the "bypass" position. By the way, I bought a by-pass type, vacuum operated unit. When I took it out of the box, I blew through it to determine which holes were which, and I noticed it didn't seal very well, but thought nothing of it. So I'm thinking I'll just take it out and put some manual shut off valves in, with a bypass tube.

Question- Do you guys think the by-pass is needed? What harm would it do not to have one? Will it hurt the water pump?

Also, does the cooling system vent somehow- When I took the cap off the overflow tank, it had pressure on it. Bad cap? Or is that just how it is?

[Highbeam]

The overflow tank is part of the pressurized radiator system. Not a typical overflow tank it is hot and could blow off steam and A/F at you.

I would think it is a good thing for a small amount of coolant to circulate through the heater core just to keep it from getting funky.

[robthebuilder]

Thanks, that's what I figured with the overflow tank, I went outside and looked at it again last night. You have a point of keeping a little bit of anti freeze flowing through the core. The reason for the heater valve was to make the AC colder. So, tomorrow it will be hot out, I'll find out if it helps.

[robthebuilder]

Well guys, it works fine now. Still waiting for a 95 degree day to see if it helped the AC.

[Hardline]

I have been going around this block for a couple months. I replaced my complete system because the compressor went out. If you can get around 50-55 degree air coming out of the vents on a 100+ day you did good. JJ