ONAN starting about 2 K windings

[Matt Colie]

> I have been looking at Ken H's wiring diagram. Someone is going to have to explain to me how the starter solenoid / relay works as shown. I see
> 2 coils labeled only as K It seems to me that the lower (right) coil would be energized by K1 and in turn would close the K contact to power the
> starter.
>
> What confuses me is the other K coil (wired vertically in the diagram). It appears to me when voltage to the K solenoid from k1 is dropped, then
> the to two solenoid K coils are now in series with +12 and power is being applied by the closed K N/O contact. If this is true, we would have some
> voltage other than +12 or 0 at the K1 N/0 contact that he is reading.
>
> What am I missing here?
>
> Do we have a diode missing in the diagram?
>
> Is the diagram wrong?
>
> Ken B.

Kens et al....

The diagram is accurate. But I just read my explanation twice and I don't understand it so we are going to add something.
Print the picture:
Mark the contacts inside the solenoid Ks.
Mark the K winding in the vertical Kh.
Mark the K winding in the Horizontal Kl.

This is the way starter solenoids are built. The vertical Kh is a very high current winding that is essentially in series with the starter motor
until the contact Ks closes. Then it is by-passed. That leaves the horizontal Kl winding to hold the contacts while the starter is cranking. If you
disconnect the starter from the solenoid, the horizontal Kl winding may not have enough power along to pull the Ks contacts and make the machine
crank. So, the Kh winging gets full battery until Ks closes. Then it is by-passed.

I hope I explained that well enough.

If the Kh winding goes bad, the solenoid will often not make at all, but it will draw current.
If the Kl winding goes bad, the solenoid will chatter (and battery voltage looks good?).

Care to guess how I learned all about this???

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[william shourt]

Matt and Ken I have read this several times and i am not able to get my head around what you are saying, I plead old age.
I just tried it again but this time I read the voltage at the start solenoid where the wire from K1 hooks on. When the starter is cranking 12.5 volts, engine starts, starter keeps running and meter shows 8.3 volts. When I disconnect wire at K1 voltage drops to 0 and starter disengages.
Do you think that the 8.3 volts is leaking from the board-K1 side or the starter side or ???

>

>> I have been looking at Ken H's wiring diagram. Someone is going to have to explain to me how the starter solenoid / relay works as shown. I see
>> 2 coils labeled only as K It seems to me that the lower (right) coil would be energized by K1 and in turn would close the K contact to power the
>> starter.
>>
>> What confuses me is the other K coil (wired vertically in the diagram). It appears to me when voltage to the K solenoid from k1 is dropped, then
>> the to two solenoid K coils are now in series with +12 and power is being applied by the closed K N/O contact. If this is true, we would have some
>> voltage other than +12 or 0 at the K1 N/0 contact that he is reading.
>>
>> What am I missing here?
>>
>> Do we have a diode missing in the diagram?
>>
>> Is the diagram wrong?
>>
>> Ken B.
>
>
> Kens et al....
>
> The diagram is accurate. But I just read my explanation twice and I don't understand it so we are going to add something.
> Print the picture:
> Mark the contacts inside the solenoid Ks.
> Mark the K winding in the vertical Kh.
> Mark the K winding in the Horizontal Kl.
>
> This is the way starter solenoids are built. The vertical Kh is a very high current winding that is essentially in series with the starter motor
> until the contact Ks closes. Then it is by-passed. That leaves the horizontal Kl winding to hold the contacts while the starter is cranking. If you
> disconnect the starter from the solenoid, the horizontal Kl winding may not have enough power along to pull the Ks contacts and make the machine
> crank. So, the Kh winging gets full battery until Ks closes. Then it is by-passed.
>
> I hope I explained that well enough.
>
> If the Kh winding goes bad, the solenoid will often not make at all, but it will draw current.
> If the Kl winding goes bad, the solenoid will chatter (and battery voltage looks good?).
>
> Care to guess how I learned all about this???
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
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[Ken H.]

William,

It's about as much of a WAG as anything else, but at least it's based on a
little-known fact:

When you say you measure "at the start solenoid where the wire from K1
hooks on", I take it to mean at terminal "S" on the diagram and the
solenoid. Correct?

If so, and disconnecting at K1 means disconnecting the wire leading to "S",
then my hypothesis could be correct.

Unlike any other solenoid relay I've ever seen, the K1 relay has an
internal flexible (woven) jumper wire from one of its control terminals to
the main contact disc which makes the connection between the battery
terminals. That jumper does not appear on any Onan drawing I've seen, but
I added it to my re-drawn version. You can see it as a very thin line on
"KH Onan Wiring 170723". My hypothesis is that due to an internal failure
of some sort, that jumper is continuing to conduct after KI is
"disengaged". Since it's a small wire, it has a much higher resistance
than the main contacts, so only partial voltage is applied to the starter
solenoid, but enough to keep the already-engaged starter solenoid closed.

I'd start by measuring the open circuit resistance across the K1 relay's
main contacts. Then, I'd probably disassemble that relay, as I did to
learn of the jumper back in 2000 or so, to see if everything's kosher
inside.

Rots a Ruck!

Ken H.

 

[terry1]

I guess since they configured the solenoid the same way that pinball flipper solenoids are setup they anticipated you would be cranking for an
extended period :lol:
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

 

[Ken B]

I think that I understand Matt's posting on how this is suppose to work.

Ken H,

What I think you are saying is that the K1 contact is indeed 2 contacts with a common bar or disc shorting across them when the coil is energized. In
your scenario I believe you are stating that the right side only (and not the left) contact fails to break when power is removed from the K1 coil. So
the circuit travels through the internal K1 wire and the right side contact.

I'm still thinking about other possibilities:

1. The electric choke or the horizontal wired K coil. I see a possible path to ground for the vertical wired K coil if the choke or horizontal K
coil has an internal partial short to ground.

2. The vertically wired K coil could possibly cause the same thing to the horizontal K if it had an internal short.

3. Is there a wiring error or partial short to +12 v on the wire going to the electric choke.

None of my above scenarios explains why the starter stops when the wire on terminal S is removed. This fact leads more to your explanation being
the correct one.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[william shourt]

Ken I will check that out, hell at this point I will try anything.
Terry thanks for giving me a laugh.

Sent from my iPad

>
> I guess since they configured the solenoid the same way that pinball flipper solenoids are setup they anticipated you would be cranking for an
> extended period :lol:
> --
> Terry Kelpien
>
> ASE Master Technician
>
> 73 Glacier 260
>
> Smithfield, Va.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Ken B]

If the failing component is as Colonel Ken is suggesting, what About removing the internal jumper inside the solenoid? I do not see how that would
hurt anything. I would not try it without Colonel Ken's blessing unless it can be easily reinstalled. I have no idea as I have never seen it.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[Ken H.]

If my WAG is correct, it should be obvious when K1 is disassembled. As I
said, neither Duane nor I could figure any reason for the jumper's
existence, so I don't think removing it would be a problem. In fact,
others have replaced that solenoid relay with an ordinary "Ford" relay with
no reported problem.

Ken H.

> If the failing component is as Colonel Ken is suggesting, what About
> removing the internal jumper inside the solenoid? I do not see how that
> would
> hurt anything. I would not try it without Colonel Ken's blessing unless
> it can be easily reinstalled. I have no idea as I have never seen it.
> --
>