water temperature gauge goes to red; using a temperature gun reading of top of radiator was 150F, top water hose at 140F coolant not hot, gauge red

Cat excavator water temperature gauge in cab goes to red; using a temperature gun, reading of top of radiator was 150F, top water hose at 140F. I checked the wiring at the temp sender did the disconnect wire from the temp sender; open = low, grounded wire to the machine = gauge went to full red. Installed a new CAT part number 094-5966 temp sender. After a couple mins (5) the gauge went to red. After the new sender installed and engine run 5 mins, temp top hose was 140F, bottom hose 124F, top radiator 150F. Machine Caterpillar E120B Serial Number 6JF00719 Engine 3114 Any idea as to what to do next to fix the temp gauge in the cab?

Did you Teflon tape the threads on the sender?

I’m guessing the sensor is a single-wire type. If you pull the wire off the sensor the gauge should go to zero/minimum. If it doesn’t my bet would be that it is shorted to ground somewhere between the gauge and the engine.

Coaldust said: Did you Teflon tape the threads on the sender? Click to expand... Did not use tape used paste

Nige said: I’m guessing the sensor is a single-wire type. If you pull the wire off the sensor the gauge should go to zero/minimum. If it doesn’t my bet would be that it is shorted to ground somewhere between the gauge and the engine. Click to expand... It is a single wire I pulled the wire off the sender and it did go to zero, I grounded the wire to frame and the dial went to red.

lake side bob said: Did not use tape used paste Click to expand... I asked because, tape and paste can interfere with the grounding of the sending unit. The threads should be dry. I’m just sayin’, check the easy things first.

Need to ohm out the new sender from post to body and body to ground, both cold and hot. Also, be sure your connector isn't bottoming out and touching the body.

Those temperatures are getting awful close to what we would suspect a plugged radiator I think I would start by cleaning rad externally

Shooting temp at sender maybe interesting if accessible.

Coaldust said: I asked because, tape and paste can interfere with the grounding of the sending unit. The threads should be dry. I’m just sayin’, check the easy things first. Click to expand... It had teflon tap on it, I used paste for the new one. So the tape did not cause a problem for what 20 years.

pittsburgh cat man said: Those temperatures are getting awful close to what we would suspect a plugged radiator I think I would start by cleaning rad externally Click to expand... I looked, I can see through the radiator with a light all over the surface area.

MarshallPowerGen said: Need to ohm out the new sender from post to body and body to ground, both cold and hot. Also, be sure your connector isn't bottoming out and touching the body. Click to expand... Do not understand where you are wanting me to ohm out the new sender, please explain more in detail. post to body? body to machine/ground? I take it the post is the nipple the wire is connected to? Old one was screwed in all the way, for over 20 years never touched it, the new one is the same.

lake side bob said: Do not understand where you are wanting me to ohm out the new sender, please explain more in detail. Click to expand... "New" just means "never tested in operation". Don't assume it is good just because it is brand-new out of the box.

pittsburgh cat man said: Those temperatures are getting awful close to what we would suspect a plugged radiator I think I would start by cleaning rad externally Click to expand... Is low coolant flow also a possibility.? Stuck temperature regulator maybe.? Your comment "after a couple of minutes the gauge went to RED" appears to support that theory. When the gauge is in the RED have you tried aiming the temp gun directly at the coolant temperature sender.?

Feel the radiator and see if an area is cold and another is hot. If thats the case you can get faulty readings. Have the inside of the radiator cubes cleaned.

Have you had the radiator cap off and could you see flow when it went to red??

I just had the same issue with a JCB JS235HD. Temperature monitor goes critically red within 20 mins to 30 mins. Half pf the rad was cold and half was hot to the touch. Had it flushed, and back up and running, in perfect condition. Been able to work all day without any issues since. Hope that helps.

Is the machine dying when it goes to red?

smifwal said: Is the machine dying when it goes to red? Click to expand... Yes it will as long as the red danger warning illuminate the dash. Its an immediate warning to shut the engine down to prevent further damage. In other words, it goes into a limp mode.

Kool J said: Yes it will as long as the red danger warning illuminate the dash. Its an immediate warning to shut the engine down to prevent further damage. In other words, it goes into a limp mode. Click to expand... IMHO you're crediting a 30-year-old machine with far too much in the way of electronic intelligence....... Those E-Series excavators were only one step past being steam-powered.