Engine replacement

[Gregorypaul]

Time to upgrade my 4.0 with the fresh rebuild I just got through with. One question at the back of my mind is charging the cooling system somewhat before initial startup and cam break in. Do I just fill the radiator and overfill the reservoir the night before, and just let the thermostat open at temperature and fill the block and head? or is there a tried and true method of doing this somewhat before hand. With breaking in the cam and keeping the motor running at 2000+ rpms while watching the gauges, I'm trying to avoid letting the motor idle at all during this process.
Thanks, Greg.

 

[JohnnyO]

I would just fill it as much as you can and start it normally. If you want to be picky you can pour some into the thermostat opening before you put the thermostat in (unless you already did that). Put the radiator cap on just halfway (one click) and the coolant will heat up faster and open the thermostat but since it isn't tight it will let the air bleed off sooner too. Once it's warmed up you can take the cap off so you can watch the air bubbles, just be careful you don't get sprayed. I have a Lev-R-Lock cap for that reason.

 

[Gregorypaul]

Good one, I should replace the old cap while I'm at it. I just started pulling the old motor out this morning. Pre adding coolant to the head would reduce the amount that would be needed during break in.
Thanks, Greg