Hi all, I am having some issues with my 1995 F250 RWD 5.8l truck. I did a thermostat swap and coolant flush a month ago. The truck runs well but will start to climb up on the temp gauge then all the sudden, wham, the temp goes to normal. I got a little worried so I did a water pump replace and replaced the thermostat with a motorcraft 195 degree unit plus another coolant flush. I let it set to leave all the air bubbles come up too. This morning the same thing except the temp seems to be lower after the "wham". I am going to replace the fan clutch this week when I can and hope this takes care of it. Any other suggestions?

 

It's your thermostat sticking closed. As long as the needle is still in the NORMAL range then you're good.

I replaced the water pump, radiator, t-stat, hoses, etc. on my '95 460. The impeller on the old pump was completely rusted away. Thus all of that steel is dissolved and embedded in the motor. I've flushed the coolant three times since I put the new pump in, and the coolant still looks like mud. Over time the mud has caked onto the t-stat; causing the same symptoms you have.