I have a 91 blazer 4x4 that overheats and the oil pressure gauge is all the way up to 80 I changed the thermostat and still over heats.any ideas ?

 

Does the gauge say your overheating or does the engine say your overheating? (Blowing coolant out and burning it) A little more info will help out. If your oil pressure gauge is off then maybe your coolant temp gauge is to. Unless engine is saying its overheated.

 

The oil pressure gauge staying at max means the sending unit is shot or one of the wires is open. I have seen lower rad hoses so soft that the water pump will suck them shut and cause overheating.