My timing cover had been leaking for quite some time so a couple months ago I replaced the timing cover gasket, timing chair and gear set, installed a new water pump, bypass hose, heater core, and heater core return tube. I also flushed the entire system both ways and cleaned out the heater box. When I bled the cooling system I parked on a slight hill and I have an antifreeze funnel that screws in place of the radiator cap and had an extra 6" on it to raise it up. Also the thermostat is new and a 195. I have gotten all the air out of the system and even bled everything twice to make sure. The antifreeze level in the funnel was at least 10" above the top of the heater core while bleeding the system. While up to operating temperature the gauge reads just under the 200 mark. The heat is terrible. It is only 15-20 degrees here and after 20 minutes of driving after the truck is up to temp it is still unbearable. What more can I do?

 

Trouble is, the heater core is still a 'high point' of the cooling system, both hoses run UP to it. Could install a flush T on the outlet side of the heater core, just as close to the core as you can reasonable get, start the engine, crack it open, and see if air comes out. (which I bet you will get some) Or, pull the hose apart right above the passenger valve cover, clamp off the engine side, so it doesn't leak..... pull the hose off the steel tube into the water pump, plug the tube.... Then, put both hoses up as high as you can get them, and see if you can burp the air out of the heater core. Just pour water into the return side hose. (the longer one.) Run a fair bit of water thru there. Then hook it all back up, keeping as much fluid as possible in the hoses. See how your heat is.

 

I will give that a try. I did disconnect the hose running along the passenger side valve cover, raise it up and try to burp it. However no air came out.

 

 

It's 5/8 heater hose correct?

 

Yeah.