Chevrolet Repair: Van overheats, blown head gasket, fan clutch

Question
My neighbor has a 1989 Chev. one ton Camper van and the engine over heats. He put in a new thermastate, radiator checks out fine. The radiator cap is new as well, He has put in a new water pump,all with in the last week and it still over heats. Any suggestions what the cause might be? It is a 360 engine

Answer
Hi Glen,
How did the radiator check fine? Was it flow tested?
Has the fan clutch and drive belt been checked?
Is he loosing coolant?
If he has to add coolant, but there is no apparent leak, then a blown head gasket is a possibility, as is a cracked head.

But the fan clutch is right at the top of the list.

Another thought is if the transmission is slipping, that can cause overheating.

Van