Fill block with water before starting?

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RDJ

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I was wondering if I should fill the block with water/antifreeze before starting it. It is a new engine. This is my first build and I am about to break in the engine. Or, will it fill OK just by filling the radiator? Or, should I take out the thermostat?
 
I would just fill the radiator with straight water, then add some if needed. Then after the engine has been run for (cam break-in), drain all the water and then refill with water and antifreeze. The reason for this is if you have a leak during the first start up, you only deal with water leaking out and you don't waste the antifreeze. This is what I did with my 340, You can leave the thermostat in too. Be sure your fuel lines are sealed up good and don't leak, it is nice to keep it running for the first 20 mins and not have to shut it down. Also, make sure you have a fire extingusher and a extra helper with to watch for any problems if you have to sit in the car while it is breaking in.
 
Fill the radiator just as you would normally with water and everything in it`s place. If you want you can do this when you break in your engine:

Get your engine started and set the timing, bring it up to the proper rpm.
Get the garden hose out and put it in the radiator, open the faucet just enough to let a small stream of water enter the radiator.
Crack open the petcock at the bottom of the radiator to let just enough water out that the garden hose can replenish what you lose.
During initial break in temperatures are high and this will help to keep things running cool.
You can also add a heavy duty fan in front of the radiator to assist in cooling.

I hope this helps some, good luck!
 
Some thermostats have small poppet valves in them.. I will drill a small 1/8" hole in any Tstat that doesnt. That lets most of the air bleed out as you fill it. I also use straight water for the first start. If there's any leak it's easier to clean up and fix. Dont fill hte radiator to the top... Leave the level just covering the exposed core. Heat expands fluids and the water will expand as it heats. That's why it blows out in most cases. Once the thermostat opens (during the cam break in time) then you can top it off.
 
So long as you keep the bypass hose on a small Mopar, there should be no need to drill holes in a thermostat.

Fill it up with water through the radiator, start it up with the cap in the safety position and keep a hose nearby. Once stabilized at a nice high idle for break-in, top off water before engine gets hot. Having heater on helps.
 
C130 Chief said:
So long as you keep the bypass hose on a small Mopar, there should be no need to drill holes in a thermostat..
Click to expand...

Chief, How do you figure that? The bypass routes coolant around below the thermostat so it still can circulate when the stat is closed. The only opening to the radiator is the stat.
 
I drilled three 1/8" holes in my thermostat. When I went to fill it up all the air came out of the system and I could fill it to full capacity before the engine was ever fired.
 
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