I believe Mr. George's truck is not "pouting", but it does seem to have multiple problems at the same time. Would not be the first time that water on a connector somewhere makes strange things display. A scanner would be a good idea. But, there are few electrical things that can eat a gallon of coolant, only when hot above a certain temp. The condensate drain is a good idea, and should be able to see water on pavement in appropriate spot amidships near tranny, when idling with AC on max, windows down. Water near the radiator is usually a hose clamp or the water pump. A coolant pressure test may cut back on some of this guessing, but it sure sounds like multiple gremlins awake at the same time.

 

^^ i would still check your system with a pressure tester you can rent for free from any advance auto part, orielly, or autozone. but what LRScott says sounds on the money for the kind of random issues your having... you have a loose ground somewhere...

 

if your overflow has been letting out some coolant as well savannah has a point as well... the fluid from the overflow drips down on the passenger fender liner and positioned just below it is the only connectors from the entire fuse box and engine harness to the inside cab modules... could be a corrotion issue in these two connectors as well

 

I did not ask Mr. George if he lost coolant on the 150 mile round trip Aiken to Columbia and return, it would be possible that coolant was lost during that trip, did not show up due to extra cooling provided by 70 mph breeze. The next day, low on coolant, drive a few miles, and the temp pops up. That's why I was leaning toward a water pump or loose hose clamp. But a gallon is quite a lot of loss.

And I suspect that Mr. George, having a large paddock full of vehicles, might just have a scanner sitting around. It is quite an eye opener to see what the scanner says the temp is while the guage does not move. I guess the loose ground might account for erratic guage (I chased that for a while in my Merecedes), and the scanner would tell him if he is really overheating, or if the guage is just crazy. Since the gauge circuit on older vehicles is a single resistor sensor to ground, it has a high resistance (175 ohms) when cold, moving to a low resistance (17 ohms) when hot. So a skinned wire grounding out on that circuit (or wet connector in wiring harness) could make gauge move higher. Now Mr. George used terms that might indicate the gauge moved very quickly, like "bam", and that might fit the once in a while ground on the wire. It is very hard for an engine to increase temp to overheat in fractions of a second.

 

When mine had the ground issue, it would not occur until the vehicle reached operating temperature. Then it would start to behave erratically. If he has a scanner, why not check? I agree, the leak is probably the cause. However, mine leaked and acted like it was overheating and was in fact not. Still leaks though lol. If it were me, i would hook up my scanner and monitor the temps like a hawk, and just let it idle until the leak presents itself. It is obviously a big one if it's losing a gallon.

 

Yep, and the scanner is more accurate than the "pretend" instruments LR installs. And in the case of temps, you are looking at two different sensors (and some models have both sensors in one physical case)

 

Went out and blew some stuff up at the land to THINK. I will have the race hauler home after this Saturday where we keep all the GOOD TOYS including a digital hold scanner and an instant.
On the 20 miles test run the temp was DEAD ON no heating just the weird fuses thing which SCREAMS corrosion at the connection.
Will do some more testing but I put it in the DOG HOUSE for now and running the Jeep TJ since it has been parked for about a year.
Will advise as to progress or other things. No plans to send it to the POUND YET!!

 

It was kinda funny today. I almost got a picture of it too, but it didn't last. My temp gauge went from center to redline instantly. Then it went to cold with the red overheat light on lol. The computer figured something was wrong and gave a "temp gauge fault" in the instrument display. I laughed the whole way home.

 

I would trade engine immobilization for decent instruments any day. I was thinking Mr. George might have a sticking thermostat caused by bits and pieces of trash left from the heads installation he got done. Something random floating trapped in the coolant, might have to pull stat and upeer / lower hose and flsuh block and radiator.