I replaced the radiator about 2 months ago, then my son had my truck for about a month. Got it back X Mas eve and noticed that it was not making a whole lot of heat. So I flushed the heater core . After the flush with the cap off and a funnel tool to refill it was making enough heat to cook with. So today wife and I went to store about 20 miles away and not much heat. Popped the hood and the upper hose was hard as a rock . Released pressure and have heat again . It is a new cap from when I replaced the rad. I saw in the factory service manual that make sure you get the right type rad cap. Does anybody know what I need or have a brand and number.

 

you need a 16 pound rad cap. Everything sounds good to me. The upper hose is suppose to be hard, but here's the link:
http://shop.oreillyauto.com/ProductD...pe=116&PTSet=A

 

I got heat now, went to an auto parts store that a close friend is the manager of and he gave me a cap made by Stant # 10231 that is to be used on our trucks. It now is letting flow from the rad to the overflow tank and from overflow to rad like it should., The other style cap , boxed by Federated auto parts ( T16) was not made for our rides. and was not allowing the flow to and from tank causing a pressure lock and not letting a flow to move heat. All is good now. Except replacing the heater control it has a vacuume leak and won't let heat come out at the floor. Also got my wild heat fixed with new checks. And also found that my one check was in the wrong place. It was in the line just ahead of the tee at the firewall and it should be above the tee just before it goes through the firewall. That is where my problem was with the wild heat.

 

Good info clap.