I have a L2500 Kubota tractor, and the heat gage slowly rises, until it is pegged. It's not overheating. I've changed the sending unit, and it still does it. Any help would be appreciated. Thanks Jim.
Heat gage pegged
- Thread starter soonerjim
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I have a L2900 gst and having the same problem. I have a thread here about it but no solution yet but still hoping.
Are you 100% certain it's not overheating? As in, have you measured the head temperature?
I'm thinking stuck thermostat especially if the sending unit has been changed and the same thing keeps happening...
The other thought that comes to mind would be an air pocket in the cylinder head.
Unfortunately, I'm just shooting from the hip because I don't know the engines in these tractors first-hand.
Steve
I'm thinking stuck thermostat especially if the sending unit has been changed and the same thing keeps happening...
The other thought that comes to mind would be an air pocket in the cylinder head.
Unfortunately, I'm just shooting from the hip because I don't know the engines in these tractors first-hand.
Steve
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Will the gauge slowly rise if you just turn the key on without starting the engine?
I second, on the safe side, that you check the temperature of the coolant with an external accurate thermometer.
I had a B7400 and the temp gauge didn't work right either. I took it apart out of the cluster and adjusted it so it read somewhat and I would know if I was over heating.
Find someone with an infrared heat gun that you point and squeeze the trigger and it tells you what the surface temp is. I have a Raytec.
I second, on the safe side, that you check the temperature of the coolant with an external accurate thermometer.
I had a B7400 and the temp gauge didn't work right either. I took it apart out of the cluster and adjusted it so it read somewhat and I would know if I was over heating.
Find someone with an infrared heat gun that you point and squeeze the trigger and it tells you what the surface temp is. I have a Raytec.
my 94 2350 doesn't even have a place in the block for a heat gauge. did they
make this thing bullet proof or forget,keith
make this thing bullet proof or forget,keith
Check continuity from the sending unit wire to where it connects on the back of the gauge. It should show pretty much no resistance. Any reading under 1 ohm is fine...
Next, disconnect the sending wire from the back of the gauge and sending unit and check the resistance to ground. You should not get any reading between the wire and ground if both ends are disconnected. If you do get a reading, you have a short someplace. It could be that the sending wire is rubbing someplace where when it heats up it makes better contact with the engine block or perhaps the exhaust manifold. Carefully check to see if the wire has rubbed on a sharp casting line or maybe if it turns corner on the back of the cylinder head and has rubbed on the sharp edge. Also check for any sharp edges where it might be contacting through the firewall or up under the dash.
If the sending wire tests good end to end, and is not shorted to ground, then I would be looking for a bad ground some other place. Figure out where the gauge is picking up its ground. Check the resistance from the gauge case to the negative terminal on the battery. If it's not less than 1 ohm, then check the battery cable, where it attaches to the engine or frame, the bolts that hold the steering, and finally where they attach the instrument cluster. You have to follow the whole path looking for corrosion. It might be that you will need to run a separate ground to the cluster if the way that Kubota did it has failed. Essentially, just follow the path that the ground would need to take to get to the gauge.
Finally, the only other thought that comes to mind would be a bad gauge. If the windings in the gauge itself are heating up, it could be that the resistance is changing and the gauge reading is changing as a result. If this is the case, one would be able to replicate the problem by warming up the tractor, getting a resistance reading from the sending unit when the tractor is hot, buying the correct size resistor to mimic the hot reading, and hooking the resistor from the sending unit wire to ground (disconnect the sending unit). Turn on the key and just let it sit not running. The gauge should read the same as when the tractor is hot (or pretty close). Simply leave the key in the on position for roughly as long as it takes for the problem to occur. If it happens as it's sitting there not running, then you know you've got a bad gauge.
The infrared thermometers have really come down in price and are very handy to have around.
Hope this helps!
Steve
Next, disconnect the sending wire from the back of the gauge and sending unit and check the resistance to ground. You should not get any reading between the wire and ground if both ends are disconnected. If you do get a reading, you have a short someplace. It could be that the sending wire is rubbing someplace where when it heats up it makes better contact with the engine block or perhaps the exhaust manifold. Carefully check to see if the wire has rubbed on a sharp casting line or maybe if it turns corner on the back of the cylinder head and has rubbed on the sharp edge. Also check for any sharp edges where it might be contacting through the firewall or up under the dash.
If the sending wire tests good end to end, and is not shorted to ground, then I would be looking for a bad ground some other place. Figure out where the gauge is picking up its ground. Check the resistance from the gauge case to the negative terminal on the battery. If it's not less than 1 ohm, then check the battery cable, where it attaches to the engine or frame, the bolts that hold the steering, and finally where they attach the instrument cluster. You have to follow the whole path looking for corrosion. It might be that you will need to run a separate ground to the cluster if the way that Kubota did it has failed. Essentially, just follow the path that the ground would need to take to get to the gauge.
Finally, the only other thought that comes to mind would be a bad gauge. If the windings in the gauge itself are heating up, it could be that the resistance is changing and the gauge reading is changing as a result. If this is the case, one would be able to replicate the problem by warming up the tractor, getting a resistance reading from the sending unit when the tractor is hot, buying the correct size resistor to mimic the hot reading, and hooking the resistor from the sending unit wire to ground (disconnect the sending unit). Turn on the key and just let it sit not running. The gauge should read the same as when the tractor is hot (or pretty close). Simply leave the key in the on position for roughly as long as it takes for the problem to occur. If it happens as it's sitting there not running, then you know you've got a bad gauge.
The infrared thermometers have really come down in price and are very handy to have around.
Hope this helps!
Steve
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I have a IR gun, and the temp reads just fine. I bought the tractor new, and I don't use it for anything but finsh mowing. It only has 250 hours. I'm sure it not over heating, becides the good reading on the IR gum, it has never lost any water from the overflow. I'm about ready to hook a nother gage to it.
On my L2900 the temp. sending unit isn't in he block. its in the cap over the thermostat.
I'd measure the resistance between the sending unit case itself (part that screws into the thermostat housing) and the block itself to see if it has a good ground. Should be less than 1 ohm.
That "cap" is likely made of aluminum or pot metal, the bolts that hold it are steel, the sending unit likely brass, and it is separated from the block by a gasket. In other words, I'd be looking VERY closely for corrosion where the bolts meet the aluminum. Dissimilar metals corrode over time.
Might we worth loosening and re-torquing the bolts and sending unit to see if the problem goes away...
Russell King
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http://prosportgauges.com/faqs.aspx
This should link to a page of questions on ELECTRIC SENDER gauges that describe something similar and how to fix it. In these replies it seems to be "wired wrong" or "bad connection at sender"
The previous poster may have hit the nail on the head on troubleshooting!
This should link to a page of questions on ELECTRIC SENDER gauges that describe something similar and how to fix it. In these replies it seems to be "wired wrong" or "bad connection at sender"
The previous poster may have hit the nail on the head on troubleshooting!