I drained out all of my coolant while replacing water pump, removing block heater, replacing thermostat, etc.

Question is: Should I "prime" the system by filling up the block/heads coolant passages (as much as I can) through the intake at the thermostat housing while still adding coolant to the radiator? Or is this overkill and I should just fill the radiator and continue to add coolant (while motor is running) until it reaches the correct level?

 

I've never 'primed' one as you say. Just fill it best you can thru the rad cap (Make sure you closed the rad petcock...me=d'oh). I usually let it sit a few minutes, 'burp' the hoses a few times, top it off & fire it up. The air wil rise to the highest point which on these cars is the upper hose/rad top/rad cap. (Not like some newer cars that require cooling sys air purges..)

 

Sounds good, I figured as much. But I never emptied the coolant from the block before, so I figured I better ask to make sure.

thanks

 

It is possible to have air trapped at the top of the block before the thermoststat opens. I drill a 1/8-3/16 inch hole in the edge of the thermostat to allow the air to bleed off when you're putting coolant in. An old timer mechanic taught me that 40 years ago....

 

When i did mine a couple years ago (block drain also), I filled the radiator within 3" of the opening. I turned the heater on, started the car, and let it run. Coolant dropped a lot. I kept filling slowly, with water and coolant, keeping level within 2" of the opening. As it got hot and thermostat opened, it dropped some more and I filled it more. After another 5 minutes, I shut it off and topped it off, replaced the cap, filled the overflow bottle and retopped it off after the first long drive.