the task for the day

[Maxwell-8 4,270]

Got to repair this AC Delco generator/starter from a K301A Kohler.

The complain is that the starter does not has the power to spin the engine over the compressionstroke. 

Disconnect it spins nice and high. 

Before I go an open it what should I like for? possible wear points?

Has been sitting for a while.

Bearings are noisy. have some experience rebuilding starters and alternators but not stuff that has both combined. 

 

[squonk 38,936]

How do we know it's the generator that's the problem. What kind of shape are the starter switch, battery and cables in? How clean are the grounds? An 8 HP engine requires about 65 amps to crank. If it's only getting 30 it aint gonna crank. Clean all the spots on those mounting ears. On my engine test stand, with one generator I only got a click, cleaned the ears and away it went. Clean up those rusty posts too. You'd be surprised.

 

Edited October 1, 2021 by squonk

[Maxwell-8 4,270]

10 minutes ago, squonk said:

How do we know it's the generator that's the problem. What kind of shape are the starter switch, battery and cables in? How clean are the grounds? An 8 HP engine requires about 65 amps to crank. If it's only getting 30 it aint gonna crank. Clean all the spots on those mounting ears. On my engine test stand, with one generator I only got a click, cleaned the ears and away it went. Clean up those rusty posts too. You'd be surprised.

 

I directly put power to it. Cause the cables are indeed in bad shape.

[squonk 38,936]

3 minutes ago, Maxwell-8 said:

I directly put power to it. Cause the cables are indeed in bad shape.

Where did you attach the ground? 

 

[pfrederi 17,147]

Manual section if it isn't a bad ground /connection issue..(also does engine turn freely???)

 

 

[Maxwell-8 4,270]

50 minutes ago, squonk said:

Where did you attach the ground? 

 

The body after sanded that spot.

 

42 minutes ago, pfrederi said:

also does engine turn freely

yes

 

turns over the engine slowly a get's stuck on the compression stroke and then suddenly goes over the point and then again it's stuck.

Edited October 1, 2021 by Maxwell-8

[squonk 38,936]

Auto compression release not working? You said bearings are noisy. Replace them and brushes. Clean commutator. That's about it.

[pfrederi 17,147]

curious did the S/G operate properly charging the battery??  In cranking mode both field coils work  in charging only one.  So if the series coil is bad it would not charge and the cranking force would be low...

[Handy Don 10,605]

10 minutes ago, Maxwell-8 said:

The body after sanded that spot.

 

yes

 

turns over the engine slowly a get's stuck on the compression stroke and then suddenly goes over the point and then again it's stuck.

Not enough energy going into the starter (bad connections, worn brushes) or too much being absorbed (bad bearings, misaligned belt path, improper belt tightness)

[Maxwell-8 4,270]

3 minutes ago, Handy Don said:

too much being absorbed (bad bearings, misaligned belt path, improper belt tightness)

bearings are noisy but roll free, belt is perfectly aligned and just tight enhough.

 

3 minutes ago, Handy Don said:

Not enough energy going into the starter (bad connections, worn brushes)

I suspect brushes cause the connectionshave been sanded

 

For what is that big screw on the top in pic 3

Edited October 1, 2021 by Maxwell-8

[rjg854 10,737]

Is the belt slipping on either the generator or the engine. I had that problem on a Commando 8, tightened the belt more and never had that problem again.

[Handy Don 10,605]

17 minutes ago, Maxwell-8 said:

I suspect brushes cause the connectionshave been sanded

Be sure, as well, to gently and carefully clean between the copper contacts on the commutator on the shaft of the S/G -- if there is conductive material (metal filings, brush residue) in there it bleeds current from one contact to the next which lessens the current going to the desired part of the winding.

Edited October 1, 2021 by Handy Don

[pfrederi 17,147]

two big screws one on each side hold the shunt and series coils.  I would read up a bit before just taking things apart....

[squonk 38,936]

I just took this genny apart. Cranked fine but no chargie. Coil burnt. Pretty Stinky too! 

 

 

 

[Maxwell-8 4,270]

1 hour ago, squonk said:

I just took this genny apart. Cranked fine but no chargie. Coil burnt. Pretty Stinky too! 

 

 

Intresting, It looks like one of mine have been replaced. The bottom one is rusty, the top, covered in Gunk.

 

 

Lots of dust came out but everything looks fine. Maybe the brushes are short but that wouldn't effect cranking.

Maybe the cleaning and lubing will get here going right!

 

[Jeff-C175 7,195]

While this unit may in fact be 'weak', it's always good practice to measure the voltage AT THE STARTER with an ANALOG voltmeter (so you can see at a glance rather than wait for a digital display to update).  This will pretty much tell you right away if there are deficiencies in the cabling to the starter (and the keyswitch / solenoid, etc).  As a youngster not knowing any better I once replaced a perfectly good starter because of a bad ground cable.  I learned that lesson over 50 years ago! 

 

[Handy Don 10,605]

1 hour ago, Maxwell-8 said:

Intresting, It looks like one of mine have been replaced. The bottom one is rusty, the top, covered in Gunk.

 

Lots of dust came out but everything looks fine. Maybe the brushes are short but that wouldn't effect cranking.

Maybe the cleaning and lubing will get here going right!

That "dust" may have been impeding rotation or preventing good contact between the brushes and the commutator. There sure is a lot of it.

[953 nut 51,720]

6 hours ago, Maxwell-8 said:

Bearings are noisy.

 

2 hours ago, Maxwell-8 said:

Maybe the brushes are short but that wouldn't effect cranking.

Short brushes will reduce spring tension resulting in poor contact with the commutator, and bad bearings will add drag reducing cranking power. Clean everything well, add new brushes and bearings, @squonk has NAPA part numbers, should do the trick.

One little trick I've learned is to use a short piece of PVC ( 1 1/4" I think) to hold the brushes in the spring holders while assembling the S/G.

[Snoopy11 5,713]

@Maxwell-8... you da man! I would not have enough patience to take that apart and fix... 

 

Don

[Maxwell-8 4,270]

9 hours ago, Jeff-C175 said:

While this unit may in fact be 'weak', it's always good practice to measure the voltage AT THE STARTER with an ANALOG voltmeter (so you can see at a glance rather than wait for a digital display to update).  This will pretty much tell you right away if there are deficiencies in the cabling to the starter (and the keyswitch / solenoid, etc).  As a youngster not knowing any better I once replaced a perfectly good starter because of a bad ground cable.  I learned that lesson over 50 years ago! 

 

Did put direct power to it. cause the cables let current trough even if the key was out the ignition.

That stuff will be complete renewed.

[Skipper 1,788]

Hi Max

 

You could measure if you get the right OHM in the right places. If yes, then do as 953 says. Clean up on isle 4 - New bearings and brushes, and you are good to go

 

Let's know how it went

Edited October 2, 2021 by Skipper

[Maxwell-8 4,270]

4 minutes ago, Skipper said:

Hi Max

 

You could measure if you get the right OHM in the right places. If yes, then do as 953 says. Clean up on isle 4 - New bearings and brushes, and you are good to go

 

Let's know how it went

I love the easy repairability on this old stuff, apart from the rust, can't get to the bearing as the Shaft-key is rustwelded in place.

 

 

 

 

Other side is just a plane bushing that needs to ge tlubed every 100 hours, but the cab is rustwelded in place too.

 

[Skipper 1,788]

Soak in penetrating oil/rust dissolver

[Maxwell-8 4,270]

45 minutes ago, Skipper said:

Soak in penetrating oil/rust dissolver

Il' try. But the key has swallowed a lot as can been seen from the inside of the shaft. so let's hope.

 

[953 nut 51,720]

3 hours ago, Maxwell-8 said:

the Shaft-key is rustwelded in place.

Take a Dremel with a cut off wheel and cut the key lengthwise then remove the two halves.