Hey guys I have a 78 stepside 4x4. I just replaced the radiator with one from a 79 F250. I installed a temp guage. The truck only seems to run at about 170 degrees. It has a 192 degr. thermostat. I have let this truck set and idle for 20 min. without any change in temp. My heater just blows warm,not hot. When I take off the cap to see if it is circulating , the antifreez doent seem to circulate. The top radiator hose is very hot,but the bottom one is very,very cool to the touch. Both heater hoses are getting hot so I dont think I have a plugged core. If this is a air lock problem, how do I purge this air? Which heater hose do I purge from? The one in the block or the one in the water pump?.....Thanks for any help on this one!!!!

 

you should just be able to purge the air by leaving the cap off and running the motor for a while with the heater on full, you could also put the front end up on jack stands (or park on a hill) and let it run with the cap off but this isnt recommended because it can be really unsafe.
but since you said that the top hose is hot but the bottom one isnt are you sure that the radiator isn't plugged. even if there is air in the lines you should still get some circulation.

-aj

 

What's the problem? Sounds like everything is working fine. An airlock would stop the coolant flow and the engine would overheat. The hot top rad hose shows the thermostat is opening and coolant is flowing. The cool bottom hose shows the radiator is cooling the coolant. The hot heater hoses show there is good flow there. Is the concern that the guage reads 170? Keep in mind that a 190 deg thermostat is fully open at 190 but starts to open earlier. And the larger radiator and cold weather will keep the engine colder. Also keep in mind the guage may be a little off.

Marty

 

Thanks for the info. Iam just concerned about my circulation. Should I be filling the rad. up all the way to the top of the cap hole or should i fill it up just to the bottom of the top hose hole? (ie: just about covering the circul. tubes) If so, will i be able to see the "flow" better?ill I be able to

 

the coolant level should be anywhere from the bottom of the fill neck to about an inch and a half below it