Alright, this is for a 1992 F-150 4x4 with the 4.9L 300 C.I. I6

The motor seems to want to overheat when you're not moving. Example: Was just driving it to try it out since had the new exhaust on, runs great. I kept an eye on the temp actually, ran just barley over the cold mark on the dash. Go to back in, decide I'll go up and down the driveway one last time. Do that, go to park and notice the gauge is just before the Red Hot mark on the dash. So, go drive it on the main road again, once moving the temp drops back down the cold quickly. Once you stop moving it goes back up quickly. How is it dropping so low, then flinging back up so high right away ? It needs a coolant flush bad, the coolant is brownish, some brown crud on the radiator full neck area. Any suggestions ? Also, fan appears to spin fine at idle.




~Thanks.

 

Get the system flushed and replace the thermostat first. The fan may be spinning, but not fast enough, the fan clutch may be partially shot.

 

Well, I'm going to do a real good coolant flush tonight and see what happens then go from there.