John Deere 4.5 Liter Temp Gauge Question

[JNyz]

Looking for help.

I have a 4.5 liter JD diesel.

Temp gauge was reading 240 but hoses were warm to touch and thermal gun was reading 120 top of radiator and 75 bottom of rad.

No temps over 120 after 30 minutes of running taken at different parts of the engine.

I decided to change the sender and gauge. Gauge only moved to 100 after 15 minutes. I popped wire off sender and grounded it out and gauge moved to hot.

I reinstalled old gauge and it did not move. I then reinstalled new gauge and if also didnt move. When grounded it out it did not move. So right now I have no temp gauge.

Stumped.

 

[Birken Vogt]

Is the engine actually getting warm or is a thermostat stuck or something?

First thing before messing with an electric gauge, I check with a thermocouple to see actual temp

 

[JNyz]

Sorry edited my post.

It doesn’t seem like it’s getting hot except for the old gauge that would shoot to 240 after 30-40 minutes.
I can touch the hoses, rad cap, all parts of the engine. Thermal gun reads as normal everywhere.

 

[mg2361]

Welcome to HEF JNyz!

Engine serial number? What is this engine in?

No temps over 120 after 30 minutes of running

Sounds like a stuck/broken thermostat to me. That engine should be 180* F after 30 minutes.

 

[JNyz]

Thank you. Trying to get this sorted out.
SN PE4045T599846 (Leaf Vacuum)

Gauge was going to 240 in 20-30 minutes but thermal gun would only show low numbers. Hoses warm, rad cool, I’ll shoot block close to head today.
Now temp gauge won’t work after I changed it.
Going to run it again around 8:30 est today.

 

[JNyz]

Update, ran this morning for 15 minutes. Temps with gun were low.