Home » Public Forums » GMCnet » Oh no Onan
| Oh no Onan [message #133609] |
Thu, 07 July 2011 02:09  |
jtblank
Messages: 237
Registered: June 2007
Location: Tulare, CA
Karma: 1
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I've always loved my 6K onan as it has always performed like a champ... until last weekend when I needed it the most.
I just replaced the oil pressure switch and was pleased as it fixed the oil leak and ran it about 3 hours and no oil leak, so off the the coast we went to escape the 105 temp. Two more hours and getting off highway 41 to US 101 I noticed that the rear airs were not running so I pulled over on the 101 onramp to investigate. The air wasn't running as the generator had quit, pushed the start button and a rather slow turnover but it did start for a second then surged from almost normal speed to almost stopped. Did this a couple times and finally when pushing the button no starter noise. Figured I'd give it a rest and continued on the our distination 45 minutes away and a pleasant 65 degrees. Three days later preparing to come home I pushed the start button and only a faint click, did that a couple more times and went to check out generator. Upon pulling it out it was obvious the problem was the small wire going from the positive starter lug to the solenoid was burned up. I fashioned a quick jumper with appropriate guage wire and pushed the button again, this time no click but the replacement wire got hot, so pushed the onan back into its spot and off we went back home to the 105 temp without the aid or rear air.
I haven't done any more troubleshooting as it's still in the 100's, I'm thinking the starter has either locked up or shorted internally. I'm looking for suggestions as to minimize my exposure to heat, it's midnight and still 88 with 49% humidity.
Thanks
John Blankenship
'76 Palm Beach
Tulare, CA
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| Re: Oh no Onan [message #133623 is a reply to message #133609] |
Thu, 07 July 2011 07:43  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| jtblank wrote on Thu, 07 July 2011 03:09 |
I've always loved my 6K onan as it has always performed like a champ... until last weekend when I needed it the most.
I just replaced the oil pressure switch and was pleased as it fixed the oil leak and ran it about 3 hours and no oil leak, so off the the coast we went to escape the 105 temp. Two more hours and getting off highway 41 to US 101 I noticed that the rear airs were not running so I pulled over on the 101 onramp to investigate. The air wasn't running as the generator had quit, pushed the start button and a rather slow turnover but it did start for a second then surged from almost normal speed to almost stopped. Did this a couple times and finally when pushing the button no starter noise. Figured I'd give it a rest and continued on the our distination 45 minutes away and a pleasant 65 degrees. Three days later preparing to come home I pushed the start button and only a faint click, did that a couple more times and went to check out generator. Upon pulling it out it was obvious the problem was the small wire going from the positive starter lug to the solenoid was burned up. I fashioned a quick jumper with appropriate guage wire and pushed the button again, this time no click but the replacement wire got hot, so pushed the onan back into its spot and off we went back home to the 105 temp without the aid or rear air.
I haven't done any more troubleshooting as it's still in the 100's, I'm thinking the starter has either locked up or shorted internally. I'm looking for suggestions as to minimize my exposure to heat, it's midnight and still 88 with 49% humidity.
Thanks
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John,
I have never been inside an Onan starter, but I have been inside enough others to know that this can happen when:
A - The starter load wiring is not capable and so the only power to the starter is through the start switch. (I can show you why with a good diagram.)
B - There is a problem with the solenoid that prevents it from making the main contacts.
So, I very much doubt that it is a locked up starter. Check out the conductors to the the starter first. If you don't find it there, then take the starter down.
Remember that the starter cable comes through a bulkhead fitting on the back of the power drawer.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Oh no Onan [message #133628 is a reply to message #133623] |
Thu, 07 July 2011 08:14 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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With all the recent Onan discussions, this link may prove useful:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=39734&title=kh-redrawn-onan-schema&cat=5813
http://goo.gl/sNJc8
When I had an Onan, I didn't like the OEM schematic, so I redrew it to
suit myself; perhaps it will be better for others also. It's marked
4kW, but the 6kW is identical. While the diagram's already posted
elsewhere, this is a better format, pdf.
The same album also has the details of a control board tester I made.
Not obvious is the fact that there was a Fast-On terminated lead for
each of the control board terminals and a 4-bolt temporary mounting
location for the test board. Monte Jestes now has the one I built.
HTH someone.
Ken H.
On Thu, Jul 7, 2011 at 8:43 AM, Matt Colie <matt7323tze@gmail.com> wrote:
>... (I can show you why with a good diagram.)
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Ken Henderson
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www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: Oh no Onan [message #133666 is a reply to message #133609] |
Thu, 07 July 2011 14:08 |
Don A
Messages: 895
Registered: October 2008
Location: Dallas, TX
Karma: 0
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Senior Member |
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Does this starter problem explain why the Onan quit running?
Seems to me maybe the Onan doesn't want to turn?? therefore the starter overheats trying to make it?
[quote Upon pulling it out it was obvious the problem was the small wire going from the positive starter lug to the solenoid was burned up. [/quote]
Don Adams Dallas, TX
'76 26' Glenbrook, '90 Sidekick
rebuilt by R Archer, powered by J Bounds, Koba
[IMG]http://www.gmcmhphotos.com/photos/data/6109/G2.jpg[/IMG]
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| Re: [GMCnet] Oh no Onan [message #133748 is a reply to message #133628] |
Thu, 07 July 2011 21:30 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| Ken Henderson wrote on Thu, 07 July 2011 09:14 |
With all the recent Onan discussions, this link may prove useful:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=39734&title=kh-redrawn-onan-schema&cat=5813
http://goo.gl/sNJc8
When I had an Onan, I didn't like the OEM schematic, so I redrew it to suit myself; perhaps it will be better for others also. It's marked 4kW, but the 6kW is identical. While the diagram's already posted elsewhere, this is a better format, pdf.
The same album also has the details of a control board tester I made. Not obvious is the fact that there was a Fast-On terminated lead for each of the control board terminals and a 4-bolt temporary mounting location for the test board. Monte Jestes now has the one I built.
HTH someone.
Ken H.
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Ken, that sure is more clear than the one in the Onan books.
The only suggestion I might offer (particularly and issue in this case) is a note the the windings (K) are not identical and (K) between S and contact K is very low impedance and is only supposed to be a "pull-in" winding for the solenoid.
But, if that is the biggest confusion it allows, I'll buy it. (I did actually, I pulled it in and put it in the GMC directory.) I wish I had had it when I had to trouble shoot a stupid problem I just had with mine. (A bad connection for the remote start. . . )
I really like the full nomenclature on the contactors. (The original did sort of suck in that area.)
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Oh no Onan [message #133763 is a reply to message #133748] |
Thu, 07 July 2011 23:14 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Matt,
I didn't change the starter area at all because it didn't confuse me, but
you're right about that being a poor representation. Why am I not surprised
that you're the only one to mention it during the past 10 years?
Since you're so darned smart: What's the other error (that I've known about
for years)? (Small hint, check pins 5 & 8.) No one's ever caught that one
either. And I don't even remember now whether I intentionally did it or
not, though I probably did to simplify the wiring when I replaced it all
(eliminating at least 2/3 of the total length of wire) -- doesn't matter in
"real life".
Ken H.
On Thu, Jul 7, 2011 at 10:30 PM, Matt Colie wrote:
>
> ...
> Ken, that sure is more clear than the one in the Onan books.
> The only suggestion I might offer (particularly and issue in this case) is
> a note the the windings (K) are not identical and (K) between S and contact
> K is very low impedance and is only supposed to be a "pull-in" winding for
> the solenoid.
> ...
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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