Toyota Repair: Toyota van 1984, head gasket, radiator cap

Question
Hi,
I have a Toyota van 1984 that overheats when
i drive more than 10 miles or go uphills
I have changed thermostat, radiator, cap,
water pomp belts,,,etc
I also loose cooling fluid without seeing
any under the car.
could it be that I have leeking head-gasket?
is changing a head-gasket difficult?
thanks,,,,,,,,bob

Answer
Yes it could be a headgasket problem, before doing anything else I would recommned confirming with a block test(most repair shops can do this)that the headgasket has an internal leak, it may still be leaking externally but that will not cause overheating as long as there is enough coolant in the system, if the engine overheats whith plenty of coolant and considering all the repairs that have been done then I would strongly suspect the headgasket. One quick check you can make yourself is to remove the oil cap and see if there are any light colored deposits, if water gets into the oil it will turn it into kind of chocolate milk looking substance.
Removing the cylinder head is quite a bit more difficult than most other toyotas because of the limited space, it's best to remove all of the engine covers under the seats to get access to the head.