rectifier trouble shooting

[John c 157]

I've got what I think may be a rectifier given up 

 

1978 C101 8spd. K241 engine

 

battery not charging when running, 

12.65vdc when off

12.50vdc when running

12.35vdc running, headlights on

 

Battery is new in good condition, 

 

As close to a manual as I have is one for magnum series Kohlers, based on that I read the following:

 

Neither of the stator leads show shorted or grounded, about 2~3 ohms between them, and 34ish-vac output at full throttle. So I suspect the rectifier is at fault

 

is there a chart showing points to test and values to expect to troubleshoot the rectifier ?

 

I've got others laying around, so how interchangeable are they among other sizes engines

 

Also how can you determine what amperage the stator is rated for ?

 

Thanks, 

 

john

Edited Friday at 08:46 PM by John c

[ri702bill 12,148]

The rectifier housing must be grounded. Over time, oxidation builds up on the two mounting fasteners. Try jumping the housing to ground (not the fasteners) and retest. If it works, unmount it & clean the mounting area. Some of us add a ground wire between the rectifier housing and the screw head....

A freshly painted surface can cause issues too if the rectifier is attached to it...

[John c 157]

OK, I'll try that tomorrow, this old machine has plenty of rust all over it, so this may be something. 

 

So is there a way to tell the rating of the alternator ...that doesn't involve taking the flywheel off the engine ?

[Achto 31,830]

27 minutes ago, John c said:

So is there a way to tell the rating of the alternator ...that doesn't involve taking the flywheel off the engine ?

 

The spec number on the engine should help get you this information.

 

 

[John c 157]

the spec number on the engine is 46766d, anybody have a chart explaining what the number means ?

[953 nut 66,211]

The Spec. Number is located on the engine data plate, once you have that number you can be sure what parts are correct. Unless you are absolutely sure the engine is the one kit left the factory with you can't be sure just by using the year of the 

 

[gwest_ca-(File Mod) 12,244]

That specification number is assigned to identify how the engine was configured for the intended Kohler customer. The K241 engines have their own series of spec numbers.

When you go to the parts list you will see in this case there are two different stators illustrated in it but only one is listed in the list - the one that the spec number specified.

https://www.partstree.com/models/k241-46766-kohler-k-series-engine-made-for-wheel-horse-10hp-7-5kw/breaker-ignition-3/

Another way to identify the stator is to look at the location of the regulator terminals and their relationship to each other. The 10 amp and 15 amp are different.

 

Here is where the original illustrated parts lists started. Take your spec number with you

 

 

[953 nut 66,211]

                Your engine Spec Number shows it being a 1979 K-241 which is correct for the '79 C-101.

Going into the K-241 parts manual Groupe 18 (charging and ignition) we find the number 114 applies to all components related to charging for that engine.

You have a 15 amp charging system and the parts illustrated below are correct for your engine. We know that your stator is working properly based on the test you have done. Your voltage regulator / rectifier should be a 15 Amp unit. It has three tabs in an "L" pattern. I have attached a link to the parts manual for you.

Edited yesterday at 12:25 PM by 953 nut
add photo

[pfrederi 20,584]

[John c 157]

Mine has the "L" shape connector plug, indicating a 15A charging system then I guess.

 

So I started with simply adding a battery ground connection to the case of the rectifier with so change seen in voltage, so then I took it off completely cleaned all the electrical connections with fine sandpaper, contact cleaner and compressed air, also took the 3 wire connector plug apart and did the same thing. I added a wire from battery ground to under the bolted connection that holds the rectifier to the frame. Once back together I was seeing 13.65vdc with the engine running, but not a steady state 13.65, it slowly fell back to about 12.40, Once there it would maintain that level when adding load to it (headlights) 

 

The fact it holds voltage under load makes me think it's working, but then why won't it hold 13.5 +, and then the 12.4vdc looks to me like the ignition is running on the battery alone. 

 

Does my new ground sound sufficient and I do in fact have a defective rectifier ?  Or should I add a tapped screw to one of the cooling fins on the rectifier to make grounded connection

 

Any of you guys been down this path before ?

Edited 21 hours ago by John c

[pfrederi 20,584]

Sounds like time for a new rectifier....

[John c 157]

that's what I'm thinking too, 

 

How much interchangeability is there among these things, I've got several on hand, I suppose they're rated in amps or maybe watts ?  Anybody know ? Since the plug configuration is dependent on the rating, maybe anything with an "L" shape plug should be compatable ?

 

I'll dig through the junkyard in a little while and see what I have

[pfrederi 20,584]

The big finned ones are usually  either 10 or 15 amp just match the terminal pattern.

[John c 157]

I took one off of a B80 exact look alike, does the exact same thing. 

 

Now is probably the perfect time to wonder if the ammeter delete would affect the recifier.....

[pfrederi 20,584]

Have you load tested your battery?

 

So many problems in the electrical forum resolve to bad grounds or a bad battery

[John c 157]

No I've not, not really certain how to, besides taking it to the auto parts store. I could put the battery in another tractor and take some readings there, I've also got another recifier from a B100 I could try. 

 

Is the ammeter crucial to the proper operation of the charging system, the one that was in the C101 was kind of suspect, it looked like a ground fault waiting to happen, so I by passed it.  Isn't there a diode inside the harness coming from the alternator, could that have a hand in this you think  

[pfrederi 20,584]

Poor mans not so accurate load test. Hook up your multimeter ..should be 12.6 volts.  Start cranking in voltage drops below 9 bad battery.

[John c 157]

The battery I'd thought was good, may well be NFG, yeah it was bought new last november, but it's layed around the shop all winter in and out of various machines and not much down time on charge. I'll move it into a machine and verify charging before hand to see how it responds.