Hourmeter says 48 hours in a day !

[58jeff]

Any idea why my hour meter on my case 580 SL Back Hoe is running too fast ? I have to manualy energize the alternator also to start the charging circut, if I leave the wire hooked up it will kill the battery overnight I havent been able to afford the service manual or I would start tracing wires
THX
JJ

[monsta]

No idea. My tractor is the opposite. Runs 3 hours too every 1 on the hour meter. It's great. Until the big bloke who bought it off me works it out. No just kidding. My missus thinks i been bludging for the last year or so. Sorry just new.

[bill onthehill]

A lot of hour meters and tachometers run off the alternator. As to why it would double up I can't help but others on here will chime in with a solution to your problem.

[Phil]

My electrical knowledge is rather weak, but if it were mine I would take the alternator in and have it checked at one of those shops that rebuilt starters and alternators. Take it to one you trust.

Have them explain, since they have your alternator in front of them, where the wires that attach to it, go. I'm assuming there is more than one wire. Sometimes one of the wires is a tach wire. One may be live always(usually a larger gauge), and another maybe live only and only when the key is on. Then you can go back, with the alt you know is okay, and check your wiring with a meter.

Maybe your hour meter is separate, and only needs a 12V supply to run it. If so it may just be defective or the problem may be feedback from the alt. I would fix the alt first, in case the problems are related. Phil

[gggraham]

The hour runs off one leg(field) of the alternator, in other words if you hook a multi meter up to it the W terminal you will see 8volts ACor if you hook it up to DC you will see 1/3 of the DC output or approx 4volts. If you have to hook a wire up each morning to start it charging check the following.
Turn the key on, is the alternator light on?
If the bulb is not on swap the alternator bulb with say the oil pressure bulb. Is the alternator light on now?
If so you have solved your problem, a lot of times the bulb will burn out and when it does you have no field voltage.
If the bulb is still not lit take the field wire off the alternator and put it to a ground( the alternator casing will do) Is the light on now? If the light is on now you have bad brushes, possibly bad diode...remove the alternator and have it checked.