G1800 temp gauge query
- Thread starter philkent
- Start date
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
2nd sending unit could be bad as well or maybe NOT the correct one ! Does the fuel gauge work properly ? Without a schematic, I don't know if they're fed from the same regulated power source. I would locate the 'specs' for both gauge and sensor and then bench test. If the sensor is say '200 ohms for cold', replace sensor with a 250 ohm pot or rheostat and test gauge.
Take an infrared thermometer and shoot the neck of the radiator when it reads hot and report back your findings. Could be a bad gauge but unlikely. More likely a sensor as already suggested or no coolant flow.
Sent from my moto z4 using Tapatalk
Sent from my moto z4 using Tapatalk
There are several reasons why the temp gauge might show high temp while the radiator is not hot.
The main reason would be thermostat stuck closed. (no flow thru radiator)
Another reason would be waterpump not pumping (again, no flow thru radiator)
Before there is MAJOR damage to your engine, you need to figure this out.
The idea to use infrared thermometer is a good start. BEWARE these are notoriously inaccurate based on the material, surface-finish. surface-color, distance and even the angle you point the thing. (not many folks read the the instructions)
Did you try to put the guage-sensor in hot water along with an ACCURATE thermometer? This is a simple way to validate accuracy.
The main reason would be thermostat stuck closed. (no flow thru radiator)
Another reason would be waterpump not pumping (again, no flow thru radiator)
Before there is MAJOR damage to your engine, you need to figure this out.
The idea to use infrared thermometer is a good start. BEWARE these are notoriously inaccurate based on the material, surface-finish. surface-color, distance and even the angle you point the thing. (not many folks read the the instructions)
Did you try to put the guage-sensor in hot water along with an ACCURATE thermometer? This is a simple way to validate accuracy.
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The wiring harness may be damaged and shorting out against the frame or engine. Mice eat insulation and cause shorts.
A disconnected gauge will read COLD. A grounded gauge will read HOT. The fact that it quit misbehaving might only mean while troubleshooting you moved that wire away from the electrical-short.
(When I bought my used M4700, the short test-run we made before paying cash for it didnt last long enough to see if the gauge ever warmed up. After a week of ownership it was discovered the temp gauge didnt work...it remained on cold. Mice-damaged wiring was repaired and the gauge then worked fine.
The battery died and that is how I discovered the alternator was only producing 11 volts due to a bad regulator. The M4700 did not have a separate charge indicator. It has a low fuel warning that doubles as a charge-fail-indicator. That told me the low-fuel indicator-light also didnt work. Sure enough, the previous owner, after suffering mouse-eaten-wiring damage, REMOVED the lamp and socket completely from the tractor. This prevented my notice during the short run during pre-buy that no charge was being made. The recent date on the tractors battery indicates he solved his problem by buying a battery, removing the warning lamp assembly, and selling the tractor. The new battery prevented any notice by a casual buyer that the alternator was no good.)
To my embarrassment, I have to admit I didnt follow my own advice to others. I didnt do a very good pre-buy inspection. I could have put a voltmeter onto the tractor during that pre-buy and it would have been instantly apparent that 11 volts meant a charging-problem. A longer engine run would have revealed an inoperative temp gauge. I should have been more inquisitive when I asked the seller if any manuals come with the sale, and he responded, No, all manuals do is feed the mice.
DOH! I must have been asleep at the wheel. But the tractor looked so clean and the hour-meter such low-time and another potential-buyer at-the-ready applied just-enough pressure for me to want to quickly close the deal and get my new-to-me tractor on the trailer and get home with it.
Frankly, I was lucky to find the fixes were a few simple butt-splices after I opened up the instrument cluster, and a cheap ($18) regulator-chip in the failed alternator I could replace myself. Im a moderately-capable mechanic and that made my mistakes into easy fixes. But it also revealed my weakness when Im excited about a new tractor!
Ill bet you find your temp gauge wiring is damaged.
A disconnected gauge will read COLD. A grounded gauge will read HOT. The fact that it quit misbehaving might only mean while troubleshooting you moved that wire away from the electrical-short.
(When I bought my used M4700, the short test-run we made before paying cash for it didnt last long enough to see if the gauge ever warmed up. After a week of ownership it was discovered the temp gauge didnt work...it remained on cold. Mice-damaged wiring was repaired and the gauge then worked fine.
The battery died and that is how I discovered the alternator was only producing 11 volts due to a bad regulator. The M4700 did not have a separate charge indicator. It has a low fuel warning that doubles as a charge-fail-indicator. That told me the low-fuel indicator-light also didnt work. Sure enough, the previous owner, after suffering mouse-eaten-wiring damage, REMOVED the lamp and socket completely from the tractor. This prevented my notice during the short run during pre-buy that no charge was being made. The recent date on the tractors battery indicates he solved his problem by buying a battery, removing the warning lamp assembly, and selling the tractor. The new battery prevented any notice by a casual buyer that the alternator was no good.)
To my embarrassment, I have to admit I didnt follow my own advice to others. I didnt do a very good pre-buy inspection. I could have put a voltmeter onto the tractor during that pre-buy and it would have been instantly apparent that 11 volts meant a charging-problem. A longer engine run would have revealed an inoperative temp gauge. I should have been more inquisitive when I asked the seller if any manuals come with the sale, and he responded, No, all manuals do is feed the mice.
DOH! I must have been asleep at the wheel. But the tractor looked so clean and the hour-meter such low-time and another potential-buyer at-the-ready applied just-enough pressure for me to want to quickly close the deal and get my new-to-me tractor on the trailer and get home with it.
Frankly, I was lucky to find the fixes were a few simple butt-splices after I opened up the instrument cluster, and a cheap ($18) regulator-chip in the failed alternator I could replace myself. Im a moderately-capable mechanic and that made my mistakes into easy fixes. But it also revealed my weakness when Im excited about a new tractor!
Ill bet you find your temp gauge wiring is damaged.
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The one at the thermostat housing would be the coolant temp sensor and the one at the front of the motor would be your oil pressure switch.
Sent from my moto z4 using Tapatalk
To expand on my earlier comment, re: temp gauge
The sending unit on most simple temp gauges is merely a temperature-sensitive resistor. When cold, it has an open-circuit/high-resistance. As it warms up, the resistance reduces/drops. When hot, it acts as a direct short.
The gauge is a needle attached to a bi-metallic strip with resistance-wire wrapped around the strip. If electric current passes thru the wire it heats up and the heat causes the bi-metallic strip to “bend”... the more current the more heat the more bending. The strip bending influences the needle toward the higher range of indication. Turning the key to the “run” position makes voltage available to the gauge, but the engine being cold, no “ground” is found because the cold sending-unit is an open-circuit/high-resistance. As the sending unit warms up, it allows more current through to ground (the engine block were it’s attached) and the increased current affects the gauge as described.
This is why a gauge that always reads “cold” may have an open circuit/broken-wire or failed sending unit and a gauge that always reads “hot” has a failed sending unit but more-likely has a shorted sending-unit wire.
Hope this helps understanding of that type system.
The sending unit on most simple temp gauges is merely a temperature-sensitive resistor. When cold, it has an open-circuit/high-resistance. As it warms up, the resistance reduces/drops. When hot, it acts as a direct short.
The gauge is a needle attached to a bi-metallic strip with resistance-wire wrapped around the strip. If electric current passes thru the wire it heats up and the heat causes the bi-metallic strip to “bend”... the more current the more heat the more bending. The strip bending influences the needle toward the higher range of indication. Turning the key to the “run” position makes voltage available to the gauge, but the engine being cold, no “ground” is found because the cold sending-unit is an open-circuit/high-resistance. As the sending unit warms up, it allows more current through to ground (the engine block were it’s attached) and the increased current affects the gauge as described.
This is why a gauge that always reads “cold” may have an open circuit/broken-wire or failed sending unit and a gauge that always reads “hot” has a failed sending unit but more-likely has a shorted sending-unit wire.
Hope this helps understanding of that type system.
no they have a sensor and a switch. The sensor is IN the head, the switch in the thermostat housing. The switch turns on the horn. There's a horn under the rear fender that goes BEEEEEP when the engine is overheated.
Very likely to be experiencing a typical G1800/G1900 problem--poor wiring connection and/or corrosion. Under the dash are several connectors. Pull them apart and CLEAN them. Then there's another one WAY underneath the tractor's frame, like under the radiator. That one is a bear to get at, easiest to pull the deck off and lay underneath. Also check your GROUND, as they're also notoriously ill. There is a ground cable (kubota calls it "earth cord") from the battery to the frame. THEN there's a short jumper between the engine and the frame, remove both, clean the connections, clean the frame, the bolt head, threads, and then reinstall all of em. If that stuff don't solve it, pull the cluster out and check the cluster connector for dirty/poor connection. If all of that is verified "good", now you can remove the sensor (not the switch, unless you just want to hear the horn), ground the wire connector to the engine somewhere and see what the gauge does. If gauge does not move, gauge is likely at fault. It should go to full hot with the wire grounded. If it does, the sensor may be at fault and it is easy to test using a pot of distilled water, a thermometer in the water, and a way to heat the water. You will measure the sensor's resistance as you heat the water. Resistance should slowly and steadily decrease as the temp increases.
Very likely to be experiencing a typical G1800/G1900 problem--poor wiring connection and/or corrosion. Under the dash are several connectors. Pull them apart and CLEAN them. Then there's another one WAY underneath the tractor's frame, like under the radiator. That one is a bear to get at, easiest to pull the deck off and lay underneath. Also check your GROUND, as they're also notoriously ill. There is a ground cable (kubota calls it "earth cord") from the battery to the frame. THEN there's a short jumper between the engine and the frame, remove both, clean the connections, clean the frame, the bolt head, threads, and then reinstall all of em. If that stuff don't solve it, pull the cluster out and check the cluster connector for dirty/poor connection. If all of that is verified "good", now you can remove the sensor (not the switch, unless you just want to hear the horn), ground the wire connector to the engine somewhere and see what the gauge does. If gauge does not move, gauge is likely at fault. It should go to full hot with the wire grounded. If it does, the sensor may be at fault and it is easy to test using a pot of distilled water, a thermometer in the water, and a way to heat the water. You will measure the sensor's resistance as you heat the water. Resistance should slowly and steadily decrease as the temp increases.