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I'd have to disagree a little bit because once the engine is up to normal operating temp the needle should "move" depending upon driving conditions like heavy commuter traffic, stop and go traffic or up/down hills and then go back to a cooler condition when the air flow thru fan are drawn in, assuming you have a stock application, ie: belt drive fan blade, fan clutch but no electric fan etc.

A decent tune up will keep the engine from laboring, running hotter/leaner too.

First I would check the condition of the thermostat to make sure it's working, you can test it in hot water to see if it opens and closes, then check the "temp guage sending unit" towards the front of the lower intake manifold and see if there is enough voltage thru the wire lead to the sending unit, this tells the dash guage what the actual temp is so low voltage could mean "false reading" on the guage and or temp guage sending unit....

If you don't know how old the unit is I would replace it, the Brass style costs around $9.99 and is the best, NO PLASTIC UNITS...lol lol

After driving and engine shut off, the top radiator hose should be hot indicating the thermostat is working... hopefully you have the correct designated temp stat for your yr BKO, mine is a 195 degree thermostat.

If you haven't done it in a while I suggest you "backflush" the cooling system with plain water until it comes out clear indicating the inside of the engine passages are fairly clean and free of any rusty sludgey build up AND wash any re-useable heater, bypass, radiator hoses and over flow tank in Tide to remove and keep any residual from recirculating thru the system and the engine will run cooler this way along with the benefit of nice heat in the winter time depending on your region.

There are always other things you can look for such as leaky old T-stat gaskets, leaky side tanks on the radiator, freeze plugs, water pump leaks, hoses clamps not tight enough etc. etc. that don't always show up right away leaving tell tale signs on the garage floor so look around to see if there are any "trails" left behind from coolant travel and go from there.

I swapped in a new 302 EFI long block in Sept. 08 and everything is new and working great, the temp needle usually sits between the NO/RMAL, fluctuating according to traffic conditions but swings back when air flow and circulation are better etc. keep in mind a lot also depends on how many miles you have on your engine too, Broncos are thirsty critters so keep the radiator topped off and the overflow tank about 1/3 full and you're good to go!


Good Luck ~ :thumbup
 

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I had a flex fan on mine, too noisey so I got rid of it and replaced it with a used solid fan/used fan clutch. The guage usually runs between R and M, but on hot days(like its been) with a/c on and on the freeway it runs NORM/AL, running a little warm? I'll test fan clutch tomarrow. Less than 3,000 miles on rebuilt 351
 

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Discussion Starter #8
Thanks guys.. i will check things out. yeah the temp gauge does not ever move so someting is up i did see that my overflow tank is nowhere near the cool mark. i do not have a hot marking on my overflow tank.
 

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Thats where my gauge goes, right to the N of normal. I have a mechanical too and the truck is usually always at 180* on that, but N on the other gauge.
 

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Discussion Starter #10
could it be the gauge that is broke ? the hose is nice and hot at shut off i need to check the voltage thru the wire lead how would i do that ?
 

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My '91 is acting the same way. :)

I bought 3 resistors from RadioShack and hooked them up in series...
10, 22, 47 (5%)

10 by itself is "hot". :)

And with 79 ohms it reads "cold" and picking 22, 32, 47 or 69 ohms
it reads places in between. :)

Pull the wire from the sending unit and ground it through the resistor/s
with the key on.

My gauge read perfect and the sending unit's resistance read ok while
cold so, on-to reading the sending unit while hot. Plan to do that next
(along side a brand new one) in a pan of hot water.

Alvin in AZ
 

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Discussion Starter #12
yeah drove around for 50 mins today AC on full blast took a temp gun to the hose 189 degree
 
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