Oil & Fuel TC30 - temp and fuel guage problems

[teststrips]

My TC30's fuel guage doesn't budge at all, never even moves no matter how full the tank is. The heat guage starts at nothing, but within 5 minutes is pegged as being too hot. The engine doesn't seem too hot, and the antifreeze never boils out or steams, but I'm afraid to use the tractor for very long b/c I don't want to cause damage (if) its really hotter than it should be.

Any suggestions on how to troubleshoot either of the problems?

 

[jinman]

For the temperature gage:
Find the temperature probe on the engine. It's probably close to where the top radiator hose goes into the engine (near the thermostat). Remove the wire going to the probe. Start the tractor and see if the temp meter stays on low or goes to maximum. If the meter goes to maximum, it's a bad meter. If it does not go up, then touch the end of the wire you removed from the probe to ground. That should make the meter go to maximum very quickly. This would be normal operation of the meter and indicate that the probe is probably bad.

The temperature probe works by changing it's resistance to ground as the engine heats up (resistance goes down as the temperature increases). If it is shorted internally or partially shorted, it will give a false reading. By removing the wire to the meter, you remove the input from the probe and indicate to the meter that the engine is running cool. By shorting the probe to ground, you are telling the meter that the engine is hot. If the meter follows that logic, then the only thing that can be wrong is a defective probe.

The fuel gage is more complex. It could be a mechanical problem (float stuck) or an electrical problem. I'm not sure if you can remove the wire and check it like the temperature probe, but it's worth a try to see if you get deflection of the meter. Just don't leave the wire grounded any longer than it takes to see some deflection or not.

BTW: I had to replace the temperature gage on my tractor because it said the engine never got very hot (just the opposite of your problem). I removed the wire and shorted it to ground. The meter only read 1/2 scale. I checked the meter using the measurements in the Repair Manual and it checked electrically good, but it was bad. The short test is pretty reliable for that gage.

 

[JC-jetro]

My TC30's fuel guage doesn't budge at all, never even moves no matter how full the tank is. The heat guage starts at nothing, but within 5 minutes is pegged as being too hot. The engine doesn't seem too hot, and the antifreeze never boils out or steams, but I'm afraid to use the tractor for very long b/c I don't want to cause damage (if) its really hotter than it should be.

Any suggestions on how to troubleshoot either of the problems?

Ditto on everything that jim had to say. I just add a bit to it. I'll post a pic of the sending unit, as Jim indicated it works on the principal of change of sensor resistance due to heat. There should be a spec for cold and hot sensor. As you see in the picture it is very easy to remove the sensor. I would follow Jim's direction first, but additionally if needed the sensor can also be independently tested by removing it when the engine is cold. Relive any pressure in the system (taking the radiator cap off), then I'll bench test the device by reading the resistance using any ohm-meter between the wire and the sensor ground cold. I'll then submerge the sensor part of it (not the whole thing) in the boiling water holding it with a plier or something, I'll then take it out and read the resistance. if you read same resistance between cold and hot you have got a defective sensor. Hot should register less than resistance that cold. If the resistance value does not jive with the established specs then you may have a faulty or out of calibration analog (needle) indicator. I don't think many of the gauges allow you to adjust high and low on the gauge.




On the fuel sending unit, again as jim said it works off of float. Float assembly can be removed from top side of the tank. You should check to see if there is any binding in the float arm and test the resistance same as the heat sending unit with only moving the arm from one extreme to another. I know on commercial set up almost always there is some small adjustment you can make for desired low and high setting to allow pump off, pump on, or alarms.

JC,

PS. Look at the attached PDF file . it shows your fuel tank and the sending unit for the fuel gauge.

 

[jinman]

PS. Look at the attached PDF file . it shows your fuel tank and the sending unit for the fuel gauge.

JC, that's a very nice diagram of the fuel tank and fuel system. When I checked my Repair Manual for my TC45D, it's fuel level sensor has two wires. The book says the resistance between those two points on the fuel float shoud be about 250 ohms when the tank is empty (float down) and about 33 ohms when the tank is full (float up). I'm not sure if the TC30 has two wires or one wire, but the reading between wires or to ground should be over a range similar to the one above.

 

[cardenharry]

On the fuel guage. If you remove the two screws and pull the guage cluster out you can see the two wires connecting to the top of the fuel tank. You take something like a short piece of copper wire and bend it so that you can connect and touch the top of the two screws the fuel gauge needle should go to full. That is how it works on my DX33 and I believe yours would be the same

 

[teststrips]

thanks everyone for the suggestions + tips - I'll try to do the troubleshooting steps + report what I find. Thanks.

 

[FredH]

Fuel Gauge on TC30's are useless at best . Mine went out after about 150 hours and warranty had already expired due to time ( did not use the tractor much in those first few years ) . Replacement is or at least was around $82 . Took old gauge apart and for $82 I was not about to spend on another piece of plastic junk . Spent $25 through JC Whitney ( plus shipping ) , bought a gauge and float kit . Installed new float with gauge temporarily mounted in one of those single gauge holders till I build a new dash out of diamond plate .

New fuel gauge is very accurate . float was very easy to set .


Fuel Level Gauge Set : JC Whitney: Auto Parts & Accessories


Has Lasted through some very rough treatment if not down right abuse .

Temp gauge is next although I will wait till I finish my dash .

Fred

 

[JC-jetro]

Fred,

I like it. Nice cure you found. They just don't make them like they used to

By the way, My fuel gauge/indicator is even more bullet proof, on my Ford 1700 I have a plastic siphon tube/sight tube thingamagic that shows the level of fuel. Of course you need to get off the tractor and view the fuel level from the side. No calibration is ever needed.

JC,

 

[dqdave1]

1999 tc-29; 1600 hours; no problem as of yet with my fuel guage.

 

[teststrips]

I guess I'll resurrect this old thread... I FINALLY got some time to work on my tractor yesterday (~6 months past my original post). I only got to the fuel gauge. I think it must have had a pretty bad electrical surge at one point - the wire wrap resistance coil had the 1st row of wires completely burnt... I was able to bridge the gap with some solder to get that working again. That wasn't the only problem though.. the gauge itself was faulty too.. one of the wires had separated from the post that it was supposed to be connected to... i had to solder that to.

Net result - the gauge now works, but it only goes down to 1/8 tank... I'll just have to remember that + fill up at 1/4 tank... its still way better than not having a meter at all.

it was very dark when I finally got done putting everything back together so I didn't get a chance to test the temp sensor... I will hopefully get to that sometime soon + will report on it.