Case 580SK Electrical Problem

[amunderdog]

Ditchdigger67 Post #13 maybe
There are three wires to alt
> Big red wire power to batteries = That was easy
> one wire plugs in = Tachometer
> one small wire bolts on = power to excite and start the alt charging --- With ignition off no power - ignition on should be minimum of 10 volts

 

[gggraham]

The dash and wiring on these SK units was not great. The W wire was always a problem. The dash in those macines are easy to trace the path, Use a spade connector and crimp it on a length of wire and plug it into the W socket at alternator. Run the wire along the RH frame rail and into the cab up to the dash area. Unplug the dash connector, the wire from the W terminal is the same color from the alternator to the plug green/yellow I think. Cut the wire 6 or 8 inches from plug and solder in the new wire. Noiw take some fine emery cloth or sand paper and make sure the connectors at dash are good and clean. This should solve the problem. Another cause of a tach bouncing is if you have the cold start package (dual battery) and one of the batteries is dead or almost dead it will cause an erratic tach.

 

[gabtrac]

Thanks!

 

[dgb]

I trouble shot my 91 K last fall when I bought it for this problem, found the W wire was broke/melted 4" from the alt. so soldered a new wire from the break with a spade to the alt. and then the dash rpm and charge would work when rpms increased to 3/4 throttle or more and remain working at any rpm until I shut it off for the day. Recently, after sitting for a few weeks, it will not work again so finding this old post is great for the new investigation. thank you 2

 

[gabtrac]

It seemed like the only way to be able to keep track of it and not lose the post, was to respond... with a thank you. Cheers.

 

[dgb]

yes, it would be nice to have a save option for relative helpful info on here. I printed the page to add to my book notes. I just checked the W terminal and only have .037 ac V so seems the alt. is bad, going to have it checked. I think there must be a connection in the alt. that corrodes from sitting ?? I will post later on the test and fix.

 

[dgb]

I took the alt. to a ele. motor place and after testing it on a machine confirmed it was dead. Don't know why it took so long to finally burn out.. He also hooked up the new one and it showed a good charge, 14+ v. He said the AC volt @ the W terminal will be half of the output DC voltage. But, hooked up the new one to the hoe and it also would not charge or run the tach, none or very little AC volt at the W terminal, Until I sped up the idle to almost full and then it kicked in.. Wondering now if this is normal for these to only start to work when rpm's are high? I will ask the ele. guy tomorrow.

 

[Tinkerer]

There are self-exciting regulators available for Bosch alternators that eliminate the need to speed up the motor to start charging.
I don't about your particular one.

 

[dgb]

Ok thanks, on a sidenote, when I brought the alternator in for testing the first thing the guy said is where is the fan? Apparently previous owner replaced it with one that didn’t have a fan. Also, to get that pulley off the alternator, he took a socket and hit it very hard with a hammer three times before it would loosen There is a retainer inside the pulley that prevents it from coming off or loosening . I am very sure I would have ruined that pulley if I had tried it myself with a puller. So that’s the good, bad, and here’s the ugly. It wasn’t until I got home and looked online for that alternator and the very same thing on eBay sells for $80 with shipping. I paid $195.

 

[gabtrac]

There are self-exciting regulators available for Bosch alternators that eliminate the need to speed up the motor to start charging.
I don't about your particular one.

Hey Tinkerer, thanks for this. Would you by chance know the part number of the Bosch that would fit my 90's 580SK? Cheers.

 

[Tinkerer]

Case #A187623 is the Bosch OEM.
They are used on Case, John Deere, Caterpillar, Ford and a lot of other mfr's of equipment.
Less than $80.00 for an aftermarket brand on eBay.