When the truck is running, I squeezed the top radiator hose and it was "soft" does this mean I need a new radiator cap or is there a bigger problem? Thanks, Alisa

 

Normal...the only time it flows is when the thermostat opens

 

Do you think it could be stuck closed? It's been overheating but not all the way in the red. Just when I stop for a light. Once u get rolling again it cools down....

 

Lets not talk radiator cap right now, am more interested in the problem not a remedy. Please describe the getting warmer at stops. Also what are we working on, year, make, engine and changes to cooling system that you are aware of.

 

1991 F150 custom 4.9L inline 6 cyl... The temp gauge is "normal" while driving, when I stop for a light the gauge slowly climbs to hotter than usual but not all the way up into the red. Once I start going and get up to about 45mph it goes back to normal....

 

Not aware of any changes to cooling system, I bought this truck back in April of this year. I do know that it needs a valve cover gasket and a new muffler, would that have anything to do with it?

 

yep...your T-Stat may not be opening...or your water pump is taking a dump...anything from the weep hole under the water pump ?? and answer Bill's questions ...that would really help.

 

Also check the fan clutch that will make it heat up at idle then cool back down once air starts going through the radiator when truck starts moving.
The should be some resistance while trying to turn the fan by hand if it spins freely the clutch is bad.

 

what he said...

 

sounds like a fan clutch to me, you can drive the 300 forever with no fan as long as your moving forward it will stay cool. but when you stop it warms up. and still wont over heat.