My friend recently bought a 86 Rx7 (13b, non turbo), so far he replaced the clutch fan, thermostat and water pump. What was happening was it was overheating and the anitifreeze was going into the overflow tank and it was spilling all over the place. He changed those 3 parts and it doesn't seem like he's having that problem with the overflow tank anymore. He said it just overheats when he's idling but when he drives it goes down. What do you think could be wrong besides a new radiator?

 

change the heater hose under the oil filter , it sounds like he has a bad soolant seal to me though

 

Does he have the fan shroud on it???????????? If the fan shroud aint there, it'll overheat at idle at a stop.

hope its that simple,

does the exhaust smelll like coolant??????

 

First check out the above suggestions.
If it still is running hot check out this long shot.

Would you believe the water pump housing?
The aluminum casting behind the pump can get eroded by the turbulence of the high revving pump.
The bypass valve seat under the thermostat can get eroded away, and there is a small bleed hole in the internal wall between the inlet and outlet side that can get enlarged.
All this bypassing gives symptoms like a partially blocked radiator.
I repaired one with Bondo Marine Epoxy Putty Stick.
It was still holding a year later when I sold the car.