i need help with cooling.......

my brothers 1988 isuzu trooper ii is losing coolant. there is no visible leaks, but it keeps using 1/2 - 1 gallon every day. is there a specific way to purge the air out or is there something else i should be looking.
i am new to isuzu, but i have experience with bmw's.
thanks
tim s.

I have the same year trooper. Mine was loosing coolant out the tail pipe.. turned out the head was cracked in 3 places. Ouch. Bought a aftermarket head from http://www.aluminumheads.com . Everyone over at http://www.4x4wire.com/isuzu/ recomends them.

or is it cracked at the exhaust valve????
thanks
tim s.

or is it cracked at the exhaust valve????
thanks
tim s.

I supposed it could be but these engines (4ZE1) are notorious for heads cracking.

See what im sayin? :)