A possible cause would be a blown head gasket where pressure from the piston coming up on the compression stroke is leaking into the cooling system, pusing the coolent out.

I would start with a compression test and verify if it is the #1 cylinder that is lacking compression and how much it is leaking. Next a cylinder leakage test could be done by putting compressed air into the combustion chamber of the #1 cylinder. Make sure the cylinder being tested is at Top Dead Center on the Compression Stroke.

Look inside the radiator for bubbles.


Adam
stovebolt2355
http://www.stovebolt2355.com