Temp Gauge and Sender.

[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.

Thank you

 

[Chewwy]

Have you looked in the Workshop Service Manual? They usually provide troubleshooting steps.

 

[JNyz]

No, didn’t see it. It an OBD leaf vacuum.

 

[Mike1955]

Manual never helped me. You’re got it nailed. Sending unit, temp gauge panel or the wires between.

 

[CliffordK]

Are you using OEM JD parts?

Make sure you actually shoot the temp sending unit and head/block with your heat gun. The thermostat could make the radiator appear cooler than the rest of the engine.

 

[JNyz]

Manual never helped me. You’re got it nailed. Sending unit, temp gauge panel or the wires between.

I put a new sender and gauge in and now gauge doesn’t work. Is there a way to test?
Can I run a wire from sender directly to gauge or does it need to go through computer?
Oh, can I text wire for conductivity?
Thanks

 

[JNyz]

Are you using OEM JD parts?

Make sure you actually shoot the temp sending unit and head/block with your heat gun. The thermostat could make the radiator appear cooler than the rest of the engine.

Not sure if OEM. I ordered from equipment manufacturer. They didn’t come in a box, came loose wrapped.
I did call a JD distributor but they said it’s proprietary I believe.

Only ran it for 15 minutes today and shot top of block and head, average around 120 degrees.

 

[LouNY]

Often there will be a voltage regulator supplying the voltage to the gauge then the wire from the gauge to the sender. The sender is usually just a varying resistance changing with the temperature at the bulb end.

 

[Mike1955]

I put a new sender and gauge in and now gauge doesn’t work. Is there a way to test?
Can I run a wire from sender directly to gauge or does it need to go through computer?
Oh, can I text wire for conductivity?
Thanks

I don’t think new ones work like the old vintage. But it must be what’s between. Or maybe you bought new bad one

 

[Jerry/MT]

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.

Thank you

Have you checked to see that the thermostat is working? This sounds like a thermostat that is always open.