Bought truck two months ago. Have a difficult overheating problem. Truck has 5.0 (302). Have replaced the water pump, fan clutch, thermastat (twice), radiator flush (twice) and the belt. Did not fix the problem. The dealer has checked the temp gauge & sending unit and they stated they were o.k. and suggested replacing the water pump which I did and no luck. The temp gauge goes to normal position and then within a minute or two will go to near hot. It will go back and forth like this whether driving or parked, but it will not go hot enough to boil over. No antifreeze leakage nor water in the oil. This problem is puzzling me and am requesting some help. It will be greatly appreciated!

 

I had the same problem on an Olds with a 403 V-8. I removed the thermostat and found that I had installed it backwards. Turned thermostat around and problem was solved.

 

Thanks for the info. sometimes we overlook the most obvious things. will let you know if this is the problem.

 

if that doesnt fix the problem i suggest you go nad have your radiator checked out. it might be clogged enough to still let coolant through, but not enough to keep the truck cool. good luck!