HLR Temp Gauge Sensor

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nrowles
40C crawler
40C crawler
Posts: 20
Joined: Mon Apr 22, 2024 5:45 am

HLR Temp Gauge Sensor

Post by nrowles » Wed Aug 14, 2024 6:19 pm

Straight 450. The HLR temp gauge is not working and hasn’t since I bought it a few months ago. I checked and the wire goes from the sensor up to the plug behind the dash. I made sure the connection was tight at the sensor and it’s still not working.

Have any of you installed a mechanical gauge or is that an option? If not, I assume next step would be replace gauge and if that doesn’t fix it then the sensor?

Jim B
350 crawler
350 crawler
Posts: 2439
Joined: Sun Nov 05, 2017 11:36 am
Location: western Maine

Re: HLR Temp Gauge Sensor

Post by Jim B » Thu Aug 15, 2024 5:34 am

In theory you can install a mechanical gauge. The unknowns to me are: Is there room enough for a mechanical sensor bulb inside the housing at the location of the electric sensor and getting a gauge with a capillary tube of the correct length.

Your service manual should give you some info on testing the gauge and sending unit. What happens to the gauge reading if you remove the sender wire from the gauge and use a jumper wire to ground it (with the engine running)? What happens to the gauge reading if you ground the wire at the sending unit end? You can remove a temperature sender and suspend it (and a thermometer) in a pan of water, heat the water, and watch for the change in ohm readings as the temperature rises.

If you determine the gauge or sender need to be replace bear in mind that the ohm ranges of them must match. Senders and gauges are not all the same. If you determine replacement is needed and you go back with electric you may want to get a gauge kit with sending unit and replace both of them. You are likely aware of this; JD shows about a $300.00 price for the gauge and $100.00 plus for the sender. 

nrowles
40C crawler
40C crawler
Posts: 20
Joined: Mon Apr 22, 2024 5:45 am

Re: HLR Temp Gauge Sensor

Post by nrowles » Thu Aug 15, 2024 6:46 am

Thanks for the info. I will look in the manual to see what it says as well. Of course I had previously looked in the transmission section and not the electrical section, oops.

Am I correct in that if I remove the sending unit, oil will start to come out so I will have to plug it quickly?

Jim B
350 crawler
350 crawler
Posts: 2439
Joined: Sun Nov 05, 2017 11:36 am
Location: western Maine

Re: HLR Temp Gauge Sensor

Post by Jim B » Thu Aug 15, 2024 7:00 am

The sending unit is right in the cover over the transmission suction screen and not in a thermowell, so yes, if you pull the sending unit out the oil will come out. I think that sending unit is 1/2" NPT so the oil will come out quickly.

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