Draining/refilling coolant???

[Bobiam]

I'm changing a damaged radiator on my 986 (non S) and am also changing the green coolant that the former owner's mechanic put in when he changed a hose (he must have thought it was the source of the leak....if life could be so simple...lol).

Anyway, I can only get around 3.5 gallons of coolant out after draining the engine, both major radiator hoses where they connect to the engine, the heater lines, and the hoses at the bottom of each radiator.

Where do you suppose that the remaining 1.25 gallons are hiding? Does anyone out there have experience draining these cars and ideas about this?

I am presently refilling it with water just to flush it and will then drain it again berfore installing my new radiator and the lifetime coolant. Trouble is, the coolant that I'm installing is a premix rated for like -34 F. If there is more than a gallon of water hiding in the system that cannot be drained, my coolant ratio will go to perhaps 0 > -10F, which is less than desirable. I don't plan on driving it at 0, but who knows??? Want to do the job right.

Thanks, Bob