First it's a 85 and stock mostly. It usually runs just above mid way on the gauge but when I let it idle, like to run into the store while the ol lady is in it, it will climb to almost hot on the gauge. Sometimes it will be running like usual on the high side of normal and when I stop like to fuel up then restart it and it will be just above the low normal mark and stay there. It never smells hot, boils over or shows low on coolant. Any ideas? Flaky gauge, thermostat or water pump maybe?

 

The Ford idiot gauge is not much better than an idiot light. It's basically a go/no go indicator with a low and high parameter built in. For definitive temperatures a mechanical gauge must be used. Or, since it doesn't smell hot or boil over, go down the road with it and be happy

 

Along with the guage that is about as accurate as a slingshot flinging poo, the temp climbing up while sitting still is pretty common, particularly if the A/C (if equipped) is in use. The fan simply doesn't move enough air to keep the radiator working at peak effectiveness while sitting still with the engine idling. This is partly due to to the fan speed, and partly due to the air only having one direction to go, down, which is totally against what heat "wants" to do.....
The low fan speed at idle, combined with lack of vehicle movement, is why many older vehicles were prone to running quite warm in a traffic. The switch to electric fans by automakers helped this tremedously, as they move a lot more than an idling engine driven fan.

Ever see police or other emergency vehicles sitting on the side of the road dealing with an accident, but they have the hoods part-way open? This to help keep the engine from overheating while it's sitting still. The hood being raised allows the air a chance to escape, so the fan can pull more thru the radiator. Those guys rarely shut the engine off during their shift. Uses more fuel, but prevents having starting issues while on-duty.

If the guage climbs towards hot sitting still with engine running, but comes back down to it's usual location once you get moving, then everything is pretty much working how it was designed to do.

 

Thanks for the replies. Guess it's been to many years sense I dealt with one with no electric fan backup, been playing with Jeeps for a lot of years. Beings this thing has a/c, and I live in Arizona, maybe I should think about an electric fan, at least as a backup. But that's something for a later date.

 

KW, check your radiator for blockage. I had a similar condition on a truck I purchased that I traced to a radiator with the lower 7 inches of core plugged. With Engine running and hot, spray radiator with water and let it run. Watch the water evaporate away. On mine the bottom never evaporated and stayed cool while area that dried ran too hot to keep a hand on. After removal and flushing, sloshing it around for 30 minutes, I cleaned out in excess of 2 cups of rust scale from poor maintainance - head gasket leak and water rather than anti freeze. Problems gone. Temperatrue stays under control now. I don't have defrost or heat--- we can only wonder why.

 

" I don't have defrost or heat-" Heater core is probably plugged too.