Our 1991 trans am is losing about 2 inches of coolant a day. The mechanic saw nothing wrong with our water pump. We don't think it's a blown head gasket because we don't see anything wrong with the oil and the exhaust is clear. What could it be?
To verify if its a head gasket you would use a chemical tester you can rent at auto zone. With the amout of coolant your using you should be able to get a coolant pressure testerand pump the cooling system and find the leak that way.