My friend has no way to access the internet so I'm writing for him. His engine overheats, boils and blows steam. It overheats when standing or moving. It runs smoothly and exhibits no other symptoms. No white smoke coming out of the tail pipe.

He has done the following trying to fix it: radiator tested, new water pump, new head gasket and new spark plugs.

It's been sitting now for almost a year because he doesn't know what to try next.

Please help, Don