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| Re: Roof A/C out at 104F (of course) [message #318004 is a reply to message #317864] |
Thu, 25 May 2017 08:59   |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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You would think the compressor since it was running and not in a locked rotor situation could easily tolerate a brief Onan overspeed. Excess heat should have been removed by the R22 circulation. I think they get a lot worse torture in most camp grounds with big power swings and soft voltage sags at startup and long periods of near brownout voltages. I suspect a bad connection at one of the faston terminals that was marginal previous or a failed relay or cap. A good DVM in Ohms performing a series of unenergized continuity tests and then in ACV to get readings when energized will tell the tail. But first a simple visual inspection may show the issue under the units metal electrical box cover.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Roof A/C out at 104F (of course) [message #318006 is a reply to message #318005] |
Thu, 25 May 2017 11:51 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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The mechanical governor on the Onan N series engine is driven by 10 ball
bearings on inclined ramps located inside the engine on the camshaft gear.
As centrifugal force slings them outward, they travel up the ramps, forcing
a swash plate forward on a shaft. That shaft has a yoke attached to a right
angle shaft that emerges from the camshaft cover, veritcally. It has a
spring loaded belcrank arm swedged onto the yoke shaft. Over the years,
that swedging can become loose, allowing the belcrank arm to move
independently of the shaft. If that is what is happening in your ONAN, it
will cause the governor to "hunt", or cycle slightly faster and slower,
hunting for the spot where spring tension matches governor torque output.
NO AMOUNT OF CARB ADJUSTMENTS, DIFFERENT HOLE PLACEMENT OF THE GOVERNOR
SPRING ON THE BELCRANK ARM, OR ANY OTHER ADJUSTMENTS WILL FIX HUNTING. The
only fix is to re-swedge the end of the yoke shaft, or, if you are feeling
really lucky, sting it with a wire feed welder. But know this. This method
(welding) has been known to cause more problems than it fixes. EZ check
for this is to wiggle the belcrank arm slightly back and forth while
looking at the swedged joint. This should be done with the engine not
running.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On May 25, 2017 9:17 AM, "A." wrote:
> Luvn737s wrote on Thu, 25 May 2017 00:07
>> Yep A/C working, but Onan surging.
>
> There are several causes of Onan surging, in addition to governor linkage
> and spring anomalies there are assorted fuel system possibilities. Do you
> have the Onan 6k manual?
> --
> 73 23' Sequoia 4 Sale
> 73 23' CanyonLands Parts Unit 4 Sale
> Upper Alabama
> "Every day I become more convinced that I am the only person left on the
> planet that recognizes nonsense for what it is."
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: [GMCnet] Roof A/C out at 104F (of course) [message #318012 is a reply to message #318006] |
Thu, 25 May 2017 14:16 |
GMC.LES
Messages: 505
Registered: April 2014
Karma: -2
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Senior Member |
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The inclined races that him just mentioned can also be worn severely, causing erratic governor issues. I have seen an Onan that would hold a stable no load RPM, but would hunt erratically when the load exceeded a certain point. After much fiddling, we pulled the engine apart to inspect the governor and found heavy grooves worn in the governor cone surface where the balls run.
The wear was in the area where the engine spent most of its running time, which was with light to no loads.
I don't recall the details, but my dad was able to readjust the governor so the balls ran in a different plane on the cone, while still being able to run at the required governed RPM. This was on an old miller weld & power portable unit with a CCK Onan.
Les Burt
Montreal
> On May 25, 2017, at 12:51 PM, James Hupy wrote:
>
> The mechanical governor on the Onan N series engine is driven by 10 ball
> bearings on inclined ramps located inside the engine on the camshaft gear.
> As centrifugal force slings them outward, they travel up the ramps, forcing
> a swash plate forward on a shaft. That shaft has a yoke attached to a right
> angle shaft that emerges from the camshaft cover, veritcally. It has a
> spring loaded belcrank arm swedged onto the yoke shaft. Over the years,
> that swedging can become loose, allowing the belcrank arm to move
> independently of the shaft. If that is what is happening in your ONAN, it
> will cause the governor to "hunt", or cycle slightly faster and slower,
> hunting for the spot where spring tension matches governor torque output.
> NO AMOUNT OF CARB ADJUSTMENTS, DIFFERENT HOLE PLACEMENT OF THE GOVERNOR
> SPRING ON THE BELCRANK ARM, OR ANY OTHER ADJUSTMENTS WILL FIX HUNTING. The
> only fix is to re-swedge the end of the yoke shaft, or, if you are feeling
> really lucky, sting it with a wire feed welder. But know this. This method
> (welding) has been known to cause more problems than it fixes. EZ check
> for this is to wiggle the belcrank arm slightly back and forth while
> looking at the swedged joint. This should be done with the engine not
> running.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>
>> On May 25, 2017 9:17 AM, "A." wrote:
>>
>> Luvn737s wrote on Thu, 25 May 2017 00:07
>>> Yep A/C working, but Onan surging.
>>
>> There are several causes of Onan surging, in addition to governor linkage
>> and spring anomalies there are assorted fuel system possibilities. Do you
>> have the Onan 6k manual?
>> --
>> 73 23' Sequoia 4 Sale
>> 73 23' CanyonLands Parts Unit 4 Sale
>> Upper Alabama
>> "Every day I become more convinced that I am the only person left on the
>> planet that recognizes nonsense for what it is."
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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