My new Jinma

[3RRL]

Thanks for the replies, but I have a hunch the wiring is correct.
I'm wondering why the gauge started working after I re-assembled the thermostat housing? Then it quit working again?

 

[greg_g]

I'm wondering why the gauge started working after I re-assembled the thermostat housing? Then it quit working again?

"Sending unit" is actually a misnomer, it doesn't really send anything. One of those two sensors provides electrical ground for the temperature gauge. When the thermostat housing is separated from the block, you interrupt the path to ground (another argument against the use of teflon tape).

I know you don't want to hear this. But it still could be a wiring problem on the supply side. Alternatively, it could be a defective gauge - intermittent supply to the gauge - or an internal short in the sending unit.

As to how they work, they're essentially thermistors. Internal resistance (to ground) is influenced by the temperature of the coolant flowing over the brass tip. Externally, one side of the temperature gauge is fed a nominal 12 volts. The other side of the gauge is connected to this thermistor. The amount of internal resistance of the sensor determines the amount of the 12v supply that's permitted to pass through the gauge - to ground. That difference is reflected as needle movement.

//greg//

 

[Diamondpilot]

I was thinking the same thing as Greg. I had to replace my T-stat housing due to a crack. It was aluminum. I would try a test jumper from the sending unit to a better ground. With the housing being aluminum and there being a gasket and such it may not be getting a proper ground.

I am away from my tractor but if I remember correctly my sending unit is where your lower one is, not in the T-stat housing like you upper one.


Check the grounds and try a jumper from the sending unit to a better ground. It will be a quick easy check.

Chris

 

[Diamondpilot]

After re-reading all the post on this I would replace the T-stat no matter what. It will fail. I am away from my tractor like I said but I can get the part number for you on Friday. You can also take the T-stat to the parts store and match it up, thats what I did. I know the one I put in was a Stant Brand and 80C or there abouts. Prior to changing mine my tractor would never heat up, just stayed around 40C even if worked hard for 2-3 hours. That may be all your problem is. Just a bad T-stat and its not getting warm so there is nothing for the gauge to read.

Chris

 

[billbill1]

Rob, I bought an American temp gauge because I wanted it to read F instead of C. Mine has always ran right at 80 degrees C but I'm not smart enough to know what that means. The gauge I bought didn't come with metric fittings so I never installed it. Mine has the individual gauge instead of the cluster setup. The amp gauge quit after about a year and I replaced it with no problem. I think you could ohm your sending unit cold and see if you get a different reading as it warms up, It should change but I couldn't tell you how much. No change and I would guess that the sending unit isn't working but that would be pretty unlikely. Either not grounded or the gauge would be my guess.

 

[Diamondpilot]

Quick easy way to convert Celsius to Fahrenheit is to double the number and add 25. Example is 80C is 80x2=160+25=185F. This will get you in the ball park. It may be off 10 deg or so but all that really matters is keep the gauge out of the red.

Chris

 

[greg_g]

Quick easy way to convert Celsius to Fahrenheit is to double the number and add 25.

No Chris, that's a quick and easy way to get in trouble buying the wrong heat range. 80C is 176F.

F=(Cx1.8)+32

//greg//

 

[Diamondpilot]

I clearly stated it was meant to only get you in the ball park and could be off by as much as 10 deg. The guy mentioned he did not know how to read his Celsius gauge. My way will give him a quick idea as he is tractoring along without a bunch of complicated math or a calculator.

Chris

 

[greg_g]

I clearly stated it was meant to only get you in the ball park and could be off by as much as 10 deg.

My point exactly. The gentleman said he didn't know what 80C meant, and you basically told him it was 185 degrees. Sorry to step on your toes here, but that's just wrong. 80C is 176F. A 9 degree error like that could precipitate unnecessary troubleshooting as well as sending somebody off to the parts store for the wrong thermostat.

Besides that, now you've got us staying off topic from Rob's issue with two temperature sensors.

//greg//

 

[3RRL]

Well, I have learned a lot from your replies and I appreciate them all.
At least I'll know how to check it now. I'm thinking the sending unit for the temperature gauge is the one mounted below. Hope I'm right about that. I'm not sure about the one that is mounted on the radiator hose connection ... it might have something to do with EGR like Greg says? After testing it, I'll remove it and take off that Teflon tape to see if that makes a difference first...to see if it wasn't grounded properly.

Chris, I will be at my property this weekend, but would sure appreciate if you could get that cross reference for the T stat. For me to take it out and drive to the nearest Napa will be a half day trip, at least. That will be the next move, to replace it if I'm still not getting a good reading on the gauge.

Oh, for conversions, I use this Josh Madison free download.
It is fast and easy ... it's free too.
Josh Madison Converter