Well now folks, let me pick the collective braintrust of the mechanix here for a minute. The vehicle is a 1986 F-150/302/AOD/4X4. I posted this on FTE but didn't get much response so here goes. This truck is all stock, no mods. Lately the rising temperature gauge is making me nervous, and here's the weird part..on cold days it runs (considerably) hotter than on hot days. Go figger. Now, yes, I know these gauges are seldom accurate but mine are at least consistant. On 90deg. days the gauge reads right in the middle. On cool 45/50deg. days it's all but in the hot-zone. My theory is the fan-clutch (thermatic control..not the clutch type) is not locking up in cool weather. On start-up the fan ROARS (locked up as it should be on start-up) and soon after the idle settles down is goes quiet. You can tell when it's engaged just from the amount of air moving out of the engine bay...and of course the noise. After warming up the fan doesn't seem to re-engage even as the temp climbs. (no increase in noise or moving air) And this is with the truck setting in the driveway. Now, mind ya, it's not overheated YET. But that gauge shouldn't be on the "L" of NORMAL unless I'm pulling a trailer or going up a loooonng hill. Driving the truck in "drive" and not "overdrive" seems to keep it running cooler. More water circulating I assume. The waterpump is new, new tight belts and flushed and filled. I don't think it could be the thermostat or it would run hotter on hot days. It doesn't. I might just pick up an aftermarket gauge just to double-check the factory gauge. But as I said..it's very consistantly hot on cold days and "middle of the gauge" on hot days. Also, with the truck properly warmed up the fan can be spun with little resistance. Shouldn't it lock up? Well, lemme know fellers. Audie..the puzzled Oldfart.

 

It might be the tmp.sensor.

 

Well fellers the problem is being solved. I pondered it a bit..could be the sending unit....could be the thermostat...could be the fan clutch...could be the little thingy-a-ma-jiggy in the instrument panel that drops voltage...could be the gauge..could be any number of things. Then I thought of all the stuff I could break trying to fix this and all the stuff I could replace till I got the right part. If I snap off a bolt anywhere it means calling Cunninghams Towing to haul it down to the Georges Auto to let him fix whatever I gammahooch up THEN fix the actual problem. I've actually done that..uhhhhh...a few times! Besides..George (mechanic) has to buy Christmas gifts for his grandkids...why should I try top beat him out of a few bucks? I'll let ya'll know what it was. Ya'll take care! Audie..the "hammer-mechanic"!