Taskmaster 425a (Dong/Feng Y385)

sailonner · Jul 31, 2014

Anyone know how to check the tachometer and sender in this tractor? It is apparently the same dash instrument display as a Jinma tractor. The tach stopped working about the same time as the voltage regulator went bad, replaced that with an external Chrysler type and the alternator works fine now. Wonder how to look at voltage or other electrical measurement thru the display unit. Checked the leads at the sender connector and see +/- .022VDC (22millivolts) on one of the connector terminals when it's not connected to the sender. The sender itself reads about 1.6K ohms. Any of that make sense?
I am guessing the easiest fix is to buy one those Sendec diesel tach/hourmeters from Northern for $90, but I'm still curious if the sender of the head unit is bad?

quicksandfarmer · Aug 1, 2014

Often with these tractors the sensor goes out of adjustment. When that happens the tachometer and hour meter stop working. To adjust the sensor: with the engine off, loosen the locknut on the sensor and screw it in until it just touches the flywheel. The back it out one half turn and lock the locknut. That will often fix the problem. If not you probably need a new sensor, it's $29 from Tommy so considerably cheaper than the Northern option and your hour meter will stay accurate.

sailonner · Aug 13, 2014

Thanks Quicksand,
I played with the sender in the bell housing and it didn't change the tach readout, so I think I'll replace that part. You mentioned "Tommy" How do I contact him or the company that sells this sender/sensor?

doxford jim · Aug 13, 2014

It might just be that the tacho pickup is dirty and giving spurious readings. To clean it, disconnect the probe and then screw it all the way out so you can check the end. These have magnets on them and sometimes they will pick up metal filing and other stuff. Try cleaning the end and then replace and adjust as quicksand has described. It won't cost you anything and might be the problem.
If not then contact Tommy at Affordable Tractors out of Texas.