I bought my '83 F100, I6, 3 on tree about 5-6 years ago. Running the 100mi. trip to St. Louis and back the Temp Gauge has always had a tendency to move over next to the "H" on the Temp Gauge. Replace sending unit, no diff. But I bought some oven temp gauges and as far as I can tell the truck is just not running hot. No steam, not much overflow at all if the reservoir is at proper level...but it does raise the level up quit a bit at times...just not enough to overflow...unless it is too full.

And the gauge may move over next to the "H," and later move back to where it usually runs temp wise. Takes a 100mi. trip in hot sun for this to happen. Anyhow, I'm beginning to wonder if it is a head gasket issue causing this...air bubbles escaping and going by the sensor.

BTW, reason I'm asking now, is that I recently replaced the dash panel w/instruments because some gauges quit working. Fixed that, but noticed the Temp Gauge still acts the same. I can't think of any other reason other than a weakish head gasket seal. Any other ideas? Thanks.

 

I also had issues with my I6 running the temp guage needle close to the HIGH mark. That was before I back flushed the radiator and motor, replaced the water pump, hoses, heater core, and thermostat. Now the needle never gets higher that 1/2 up the guage.

Replacment of those cooling parts probably ran close to $100 and I did the work myself, but it was lots easier than pulling the head.

Good Luck!

 

Good idea, I think I will remove the radiator and flush both ways using a little CLR. I replaced the thermostat already...also will remove the heater hoses and flush the core out too...I'd rather not be concerned about blowing a head gasket on a long trip on some lonely...or too busy...highway. Thanks, I'll try that and see if it helps.

 

And the thing that bothers me, that the truck started to run next to the "H" about half way on a 125mi. trip yesterday until I got where I was going. Stop/Check/doesn't really seem to be hot. On the way back needle stayed about 1/4 from "C" until I got home. It's this going to "H" for no apparent reason at times that makes me think maybe Head Gasket leakage/backpressure.

I'll see how it does after the flush.

 

Is it pinning out at H, or is there still some room for movement on the gauge? If it is pinning, you may also want to chech the wire from the sensor. If it is old, or if there is a spot where the insulation has worn off, it could be grounding out and giving the false reading. Could be a long shot, but also worth checking.

 

Not quite pegging the H. Right near the last Normal hash before the H is the hottest the gauge ever showed. Sometimes it shows a little hot and cools back off. I just remember my Explorer's temp gauge doing the same...but more regularly and steady "C" to "H" wondering needle before the head gasket blew. Exhaust was escaping into the coolant traveling past the sensor. I'm hoping this is not the case again. After all, this isn't a V6 )

 

I would forget about all dash gauges on this truck. All of mine died and they have a common reputation of not being accurate. I went to advance auto and got a sunpro triple gauge combo for about 25 bucks, all mechanical. It has Temp, Voltage, and oil pressure gauges. They go besides the cigarrete lighter on my truck and I see em' without any problems whatsoever. Very easy to install also. They also come with internal lightin'. Just remove the oil pressure sending unit, and plug in the fitting and tubbing that comes with the gauge kit. For the temp gauge, route the copper tubbing to the temp sending unit in the engine and replace sending unit with new fitting in kit. Voltage gauge is even easier. Just ground anywere, and positive lead goes to any fuse that gets 12V when ignition is turned on. For the gauge's light, ground anywere, and positive lead to dash lighting fuse (number 1 fuse in diagram below). Saved me from opening engine to put new oil pump in, discovered with the new gauges that truck runs cool, and with very nice oil pressure unlike dash gauges which told me that the engine was diying. Hope this helps!

 

Yeah, I know what you mean...my Oil gauge will often do like my Temp gauge and rise next to the "H" high oil pressure mark...and sooner or later back off to 3/4 of the way in the Wide "Normal" range arc. In fact, nothing ever goes really out of that Normal arc...just to the fringe areas of it...may not really be anything wrong at all. I mean, who ever heard of running an engine Hot for an hour and never even raising a steam, get out and use an oven temp gauge in the radiator fins and get a reading of about 190 after running it hot for an hour? It does look like nonsense gauges to me too.

 

Just a thought regarding the eratic elevated temperaure. Did you notice if the oil pressure and fuel gauges also read higher than normal? I have experienced this with a 1984 and 1986 F150. The instrument cluster voltage regulator [recently discussed by NumberDummy; P/N D1AZ10804A] was at fault. As it allowed greater than normal voltage, the gauges drifted higher. Apparantly, the ammeter is not controlled by the regulator. All of the affected gauges would mysteriously return to normal.

 

My truck's temp gauge goes up to the tip of normal near the H, and then comes back to the middle, no smoke no smell, probably just the gauge. The 94 I had would never go above the very tip of the normal closer to the C.

 

Yeah - Had the same problem. I replaced mucho stats.
One thing I learned is the HD Stant stats jammed up.
The regular stats worked best.

 

I have the same symptom. My engine alternates between just above the mid-point of "NORMAL", and the high end of the box. The engine has not smelled like it was running hot when I pulled over to check, and it has a new radiator and thermostat, so I have assumed that it was a gauge thing.

I plan to add aftermarket temp/volt gauges soon because my ammeter is also inoperable.

 

On the trucks left fender (battery side), there is a small box with a bunch of cables going to it, that's the voltage regulator. It even has it written on "Voltage Regulator". That thing seems to be the culprit of the gauge problem. I don't know if there is a replacement unit for it. I still think it's cheaper and more accurate to go with the mechanical ones. They don't need all that regulator, sending units, and cables everywhere stuff.

 

i posted a thread about this too. My gauge would go past the "H" and my truck wouldnt wanna start, or it would die right away until the gauge got lower. I replaced my radiator and did a flush and put in a thermostat and the starting/dying problem got solved, however the gauge was at the "A" in normal. It still "runs hot" but I just ignore it. I plan on also buying the sunpro gauges, the only thing is i dont wanna ruin my interior. I would like everything to look stock since I have a xlt lariat. LMC has a replacement but its $89.99

 

Yeah, I know what you mean, nice truck tho. Well, I would go for the gauges, I bought em' black and they look good. I know that it is very nice to have the truck in a "stock condition" (wish mine was), but I prefer to have a almost stock interior to having a replaced engine. oh well...