pstrman

When I bought our jeep 89 Laredo, the heater core was bypassed. I hooked it up and no leaks so I thought great. I noticed that there was only water in the cooling system so I drained it and added 50/50 mix of antifreeze. Now, heater control valve is leaking and the engine temp rose from a constant 185 to dang near to the red line. I understand the heater control valve needs to be replaced but whats up with the engine temp? My son told me I cannot add antifreeze when motor is running, never heard of that either, is that right? Should also say that the vacuum line to the heater control valve is broken and needs to be replaced.

SeriousOffroad

You let a bunch of air in....

Bleed off the air.

pstrman

Is there a valve or leave cap off?

fwak1234

Let the jeep cool down and then take the radiator cap off. Start it up and let it get good and warm. The air will "burp" out of the fill for the radiator. Once it burts out fill it while its still running and make sure it is done burping. Should be good to go for the high rise in temp after that because that will purge the air...they also sell cap kits with a funnel built in for this situation but this is the backyard way that I do it and it works well.

cruiser54

Eliminat the heater control valve with a straight piece of pipe and plug the vacuum line.

Replace the cap on the bottle with a 703-1396 cap from Napa. Fill your cooling system until it's at the line in the bottle. Go drive it.