I'm real close to starting my car for the first time after ten months of "upgrades". I discovered that filling a completely dry coolant system is quite a challenge. I did some searching here on the forum but didn't really find any tricks let alone a smoking gun that solves the problem. There's plenty of info on the shortcomings of the coolant system but I was surprised there weren't more tips on filling it.
Correct me if I'm wrong here. When filling the coolant system the coolant has to travel from the swirl tank through the radiator and back to the engine. I know there is a small bleed hole in the thermostat but it is very small. The engine pretty much becomes a big air trap. I discovered this thinking I had the system full when I found one of the tricks to it. I had the back end jacked up and found the 3/8" pipe plug next to the freeze plug on the drivers side. It took some force but I was able to get it out only to find a dry engine block. Again the swirl tank was full and the block was dry! I removed the radiator cap and the air started to escape through the hole in the block. Now I was on to something. I ended up installing drain cocks in both of the 3/8" drain holes on the block to make this easier.
The next thing I found that helps was to use a coolant system pressure test kit I bought from Harbor Freight to pressurize the system and push the water through it and the air out. Say what you will about Harbor Freight if you are a professional mechanic but for me in my garage most of their things are just fine. The pressure test kit works great. I did make a rubber gasket and added a washer to help it seal in the swirl tank but other than that it is flawless. With pressure on the system I was able to get all the air out of the radiator. I installed hoses on both the radiator vent and drain and ran them down through the bottom of the valance.
Lastly I turned an arbor on my lathe that bolts to the water pump that I attached my drill to. This allowed me to circulate some water through the system and purge even more air. It really works. I'm guessing after all of this I probably was able to get 95%-99% of the air out of the system. If anyone is interested I'd be willing to make and sell some of these arbors. Let me know...
Drain cock:
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