186 electrical problem

Mike 186 · Dec 26, 2009

I got a 186 hydro. The problem is the alternator doesn't charge at low idle. The volt meter gauge stays in the green if you rev it up a little but still acts erratic or it doesn't charge like it should. alternator is only 2yrs old. I was wondering if I need to change the belt. I don't have a warm shop so any pointers would be greatly appreciated.

Owen Aaland · Dec 27, 2009

(quoted from post at 21:26:34 12/26/09) I got a 186 hydro. The problem is the alternator doesn't charge at low idle. The volt meter gauge stays in the green if you rev it up a little but still acts erratic or it doesn't charge like it should. alternator is only 2yrs old. I was wondering if I need to change the belt. I don't have a warm shop so any pointers would be greatly appreciated.

Certainly check the belt but if I had to make a guess as to what the problem is I would say that vibration has shorted out the stator in the alternator causing it lose a lot of its' output amps.

A lot of rebuilt alternators have the stators reused when they are rebuilt. On tractors and other farm equipment the heat and vibration is usually what kills the alternator. Most stators use paper spacers to keep the stator windings from rubbing on the stator laminations. The heat dries out the paper causing it to become brittle and loose and then vibration wears the insulation off the windings. If part of the stator windings have turned black it is an indication of them being shorted out. They change color when they are overheated.

The other problem that is real common is the brushes wearing out in the holders and sticking. Your tractor should have a 10SI, type 116 which has swing style brushes instead of sliding ones. That change eliminated a lot of brush problems on the tractors.

Brownie 450 · Dec 27, 2009

First place I'd look is the diode trio. One or two sections of the trio are open. As Owen has pointed out, the brushes can be worn or loaded with dirt to the point of not making good contact with the slip rings on the field.
Last fall, our 1460 had 2 of the strips out [melted] on the diode trio, & it would only charge as you have described. I have done many of these Delco alternators that have had bad trios. Check them with an analog meter on low ohms. One lead to the single terminal --the other lead to each of the other 3 terminals --one at a time. They should all read ~35 ohms or infinity. Reverse leads & check again. Readings should be opposite this time. If any of the 3 sections don't read the same, the trio is bad.
Same for the stator--check all 3 sections [wires] to ground [steel] part of the stator with the ohmmeter on Rx1 scale. This will tell if any of the sections are shorted out. Do this test on the rectifier bank while you have it apart--only you will have to check both sections to the threaded studs [total of 6 checks].

Brownie 450 · Dec 27, 2009

I should have said that the rectifier bank will test like the diode trio---~ 35 ohms one direction & infinity with leads reversed.

186 electrical problem

Mike 186

New User

Owen Aaland

Well-known Member

Brownie 450

Member

Brownie 450

Member

Similar threads