Truck runs cool when driving around town about 177. Get on the highway and the temp goes to about 195, go up a mountain pass she climbs to about 210 and I feel that If I dont back off the gas the truck will overheat because the temp just keeps climbing. Go down the highway again on a flat stretch of highway and it drops to 195, get into town temp drops to 177 and even lower when i just let the truck idle. truck has a brand new 195 thermostat, fan clutch is only a month old, water pump is about 2 years old, this truck has had head gasket issues in the past but every year I put in the bars stuff and have not had a problem with it since, I started doing the bars stuff about 4 years ago. This is the stuff you flush the system first with not the pour in stuff. 1997 f150 4.6l

 

oh BTW, I own a scangauge that is why I know what the temp actually is, and the truck normally runs between 190 and 205 after warm up.

 

you have a 195 degree thermostat. It would not be abnormal to go to 210 when climbing a hill. If it never stopped climbing that would be different. You may not have a real problem, or the long term use of BARS may be effecting you a little bit. I don't see a big problem with you present readings.

 

yeah, the low temps are what is bothering me, and the sudden change. but I guess as long as it does not overheat I am good.

 

well, I am not good, way I figure it, I got a bad fan clutch. Even if I am wrong i will post results. This will not happen until next weekend.

 

fan clutch works at low speed with not air flow. It has no value running down the road at 60 MPH.

 

true, still have no idea why it would run so cool though. when I figure it out I will post so if anyone else has the same problem they can read this.

 

A fully heated system temperature should be in the 195 range.
If it is lower, change the thermostat.
If you actually have overheating only during heavier engine loading, the radiator is partially plugged or both.
If from this, the cooling capacity is too low.
Good luck.

 

if short distances it doesn't get over 200, and long distances, it gets hotter and stays hot... Radiator.