Coolant question
 

I am putting the finishing touches on a 302. I have made a makeshift runstand and am almost to the point of crankn' er up.

How do I get the coolant through the block before start-up?

To fill the radiator alone and start it seems wrong, just as to start, stop, refill, and restart makes no sense either. Do I prime it by hand/drill and turn the water pump over, like I would removing the distributor and priming the oil pump/block/heads? Or...do I pop the upper hose and thermostat and just pour it in along with topping off the radiator?

What is the volume of coolant needed to fill the block and radiator anyway?

Feel a little like a moron to ask, but the thought of asking about "a fried motor on start-up" may be worse.

Thanks.

-John

There are a gazillion posts on this Board covering just about every conceivable scenario of this topic. Generally, drill a 1/8" hole in the backing plate of your thermostat and install the hole at 12 o'clock. That will prevent trapped air from hanging around in the water jacket of your intake manifold. I recommend jacking up the front of the car before filling the radiator to tilt the engine downwards. Make sure that your coolant filler neck is at the highest point of your cooling system. Carefull fill the radiator with a 50-50 mix of antifreeze and water. When full, let it sit for awhile to allow the air to be displaced into the radiator and then repeat the fill routine. If you have a heater with a shutoff valve make sure the shutoff valve is in the open position. Keep adding coolant/water mix until the level stays put. Cap the radiator and lower the car. Start the engine, run it to full temp for several minutes and then allow to fully cool. Uncap the radiator and add more coolant mix if needed. That should do it. If you have an overflow can fill that about half way with coolant mix. I recommend using a radiator cap that will allow coolant to be sucked back into the radiator from the overflow can during cooldown. I use one and never have to uncap my expansion tank. I merely check the level in the overflow tank occasionally.

Since you mentioned this is on a test stand it tends to reason it will be temporary. I would just use water or maybe mix a couple of quarts of coolant together unless it will be setting out in the freezing weather at some point. There is enough clearance inside the waterpump to allow it to be filled from the top of the manifold from one of the heater hose connections. Use a funnel and slowly fill the system, it will fill the block, part of the radiator, heads and manifold, it will also purge the air at the same time, leave the cap off of the radiator while doing this, when the water/coolant reaches the top of the hole using to fill it replace the threaded plug and continue filling from the radiator. Once it operates and gets up to temprature after filling it this way any remaining air will be expelled when the thermostat opens. IMO it's not necessary to get overly concerned about coolant/antifreeze mixture until it is in the car permanently. Once it is installed in the car be sure the coolant you choose is compatible with the rubber and elastomers used in the headgaskets you are using. Some of the coolants are designed to be used with certain types of gaskets/rubber etc.

Rick

Thanks guys...

Rick, I like that solution (pun?) using the manifold...In GA the garage isn't prone to freeze, but at the rate I am going it will probably be better safe than sorry to add the antifreeze. I appreciate the heads up about the difference of stand vs. car decisions.

-John

John:
Remember, antifreeze lowers the freezing point of water. It also raises the boiling point! It also lubricates the water pump. Ditto on the suggestion to drill a hole in the thermostat.

Bob