Home » Public Forums » GMCnet » Onan Adventures (Swaping out Onans)
| Onan Adventures [message #318374] |
Fri, 02 June 2017 12:33  |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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About a year ago, Steve Ferguson put out a notice on Facebook that he had a 6KW power drawer that had been completely reconditioned by an Onan dealer, that he wanted to get out of his garage. He explained that the generator came from Kerry Tandy's coach after he had been having trouble with it, and had it replaced with a new one. Kerry, so the story goes, then pointed to the removed Onan and told them to "make that one like new" I got too good of a deal on it to pass it up.
A couple of weeks ago, I decided it was time to do the swap, and drug the 'new' generator out of my garage for a test run. The night before, I had pulled the spark plugs and sprayed a healthy dose of Sta-Bil Cylinder Fogger into the spark plug holes. Saturday morning, I rigged up a gas can, and after correcting a mis-wired fuel pump, hooked it up to the coach batteries with jumper cables, and fired it up. It started almost immediately and upon checking it out, I found that is was producing a nice steady 120 volts of AC power.
I then set about removing the old Onan, using an engine hoist, and although not an easy task, had it out in a few hours. I then worked on some peripheral stuff (rebuilt the macerator, removed the batteries and Ragusa Battery tray, etc. and started re-lining the generator compartment with some two pound foam/sound deadening insulation I had gotten from Jim Bounds. I finished that all up during the evenings of the next week and was ready to stab the new generator into the hole on Memorial Day weekend.
I had it all ready to go in when my son arrived to help at about noon, and after removing a few more parts (the battery cable and fuel connection on the bottom of the drawer) we had it bolted in. We then wired in the 12 volt starting cables and the 120 volt AC connections and tried to fire it up. it would turn over very slowly, but not start. After checking the voltage draw on the starter, we decided there was something wrong with it and pulled it off. The starter had evidently been wet and the brushes were rusted into the brush holder , so we put the starter from the old generator on it. It then started okay, but still turned over somewhat slowly.
After checking the voltage and making a few small adjustments, I turned on both air conditioners. It handled them just fine, even after the compressors kicked in. I then loaded it up with the water heater, and although we could tell there was a load on it, it handled that as well (something that my old high hour unit could not do). The voltage and hertz never changed appreciably from the unloaded condition.
I worked on it some more on Sunday trying to wire in the remote panel. Covered under another thread, we had to make a few wiring corrections to the control board and trace the wiring to the remote switch, but finally got it.
Next issue was the starter. Although the old Onan's starter was adequate to crank the tired old engine, it lacked the poewer to turn the new one over at enough speed to start it. I took the water damaged starter to a local re-builder (sorry Jim K, the shipping would have killed me) and they turned it into a work of art for $88.18. I thought 'if this thing works as well as it looks, it should start it with no problem'. I installed the rebuilt starter and hit the switch and the generator fired off immediately on the first stroke.
I'm still working on a few details, which I hope to have finished up this weekend, but overall I am very pleased with the swap. Here's hoping it works out well in the long run.
I guess the cost of a full recondition of this Onan wasn't a factor for Kerry, but I've often wondered why we don't see more of that going on. Are the parts prohibitively expensive or just not available? The Power Drawer was specifically designed for the GMC and is therefore a perfect fit, so it made sense to me, to stick with it. Besides, a new one costs ~$3500.00.
My old Onan, although a high hour machine (probably 0ver 3,000 hours, the Hobbs meter was broken when I got the coach) has always been dependable with the only issues, ever, being fuel pump problems. It will be for sale if anyone needs one.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Onan Adventures [message #318376 is a reply to message #318374] |
Fri, 02 June 2017 16:07  |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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What are your thoughts as to the improvement of the sound with the smoother running and the 1 pound sound material as compared to a week ago with your other one?
I am trying to find time to de-carbon mine. No idea if it needs it, but that is about the last item to address on
My onan.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Onan Adventures [message #318380 is a reply to message #318376] |
Fri, 02 June 2017 17:08 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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lqqkatjon wrote on Fri, 02 June 2017 14:07What are your thoughts as to the improvement of the sound with the smoother running and the 1 pound sound material as compared to a week ago with your other one?
I am trying to find time to de-carbon mine. No idea if it needs it, but that is about the last item to address on
My onan.
It IS quieter with the new insulation. Of course the old stuff had large pieces missing from it, so it is probably due to having full coverage now. Also, the newer generator is not as noisy mechanically as the old one. My generator compartment is aluminum as well. Jim Bounds seemed surprised by that, stating that most are plywood or fiberglass.
I had spent quite a bit of time replacing gaskets and seals and even adjusted the tappets on the old one, but it still made more noise from the valve train, and maybe the bearings, than the new one.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Onan Adventures [message #318434 is a reply to message #318380] |
Sat, 03 June 2017 22:35 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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"I guess the cost of a full recondition of this Onan wasn't a factor for Kerry, but I've often wondered why we don't see more of that going on. Are the parts prohibitively expensive or just not available? The Power Drawer was specifically designed for the GMC and is therefore a perfect fit, so it made sense to me, to stick with it. Besides, a new one costs ~$3500.00"
Maybe this part got lost in the other long post, I'm hoping to hear from some of the Onan experts as to the feasibility of rebuilding one of our Power Drawers. We spend big bucks on rebuilding engines (even conversions) and transmissions, why not the Onan?
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Onan Adventures [message #318436 is a reply to message #318434] |
Sat, 03 June 2017 22:45 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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Read here
http://gmc49ers.blogspot.com/2015/09/onan-gmc-propane-conversion.html
Just run it
On Sat, Jun 3, 2017 at 8:36 PM Carl Stouffer wrote:
> "I guess the cost of a full recondition of this Onan wasn't a factor for
> Kerry, but I've often wondered why we don't see more of that going on. Are
> the parts prohibitively expensive or just not available? The Power Drawer
> was specifically designed for the GMC and is therefore a perfect fit, so it
> made sense to me, to stick with it. Besides, a new one costs ~$3500.00"
>
> Maybe this part got lost in the other long post, I'm hoping to hear from
> some of the Onan experts as to the feasibility of rebuilding one of our
> Power
> Drawers. We spend big bucks on rebuilding engines (even conversions) and
> transmissions, why not the Onan?
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
> Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive,
> Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American
> Eagles,
> Solar battery charging. GMCSJ and GMCMI member
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
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Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] Onan Adventures [message #318445 is a reply to message #318436] |
Sun, 04 June 2017 07:06 |
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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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This whole thing with the Onans is kind of a mystery to me. I have worked with this family of engines for years and the only one I saw scrapped go run out without oil. Yes, parts are expansive, but go buy Honda parts.
Now, I have seen more than a few that were a slimy, nasty and miserable mess. I bought one for its value in scrap metal. Disassembled it and resealed it with gasket goo and sold it.
The neighbor has one that he gave up on. It was in his lawn tractor. When he got the price for a rebuild kit, he found that he could buy a new Kawasaki engine and an adapter kit for his tractor for less, but that is not a possibility for our application.
I'm going to keep changing the oil in mine. It does run even better with the right spark plugs. It did have the wrong number for years, but one source gave a different number that I finally tried. It had the plugs for an NH in it.
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] Onan Adventures [message #318457 is a reply to message #318374] |
Sun, 04 June 2017 12:58 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
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Senior Member |
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On Jun 2, 2017, at 1:33 PM, Carl Stouffer wrote:
> I guess the cost of a full recondition of this Onan wasn't a factor for Kerry, but I've often wondered why we don't see more of that going on. Are the parts prohibitively expensive or just not available? The Power Drawer was specifically designed for the GMC and is therefore a perfect fit, so it made sense to me, to stick with it. Besides, a new one costs ~$3500.00.
I’ve worked on powerdrawers for almost 10 years now and I continue to marvel at the bad things people say about them and how frustrated owners can be - to the point of pulling out perfectly serviceable units and replacing them with some discontinued Honda or some other brand of 3600 RPM hack job. Granted, different users have different desires - some don’t care about noise, some don’t care about complexity and multiple failure modes - plus many on this list are more than capable of Macguyvering any machine to run in an emergency so a non-Onan is just perfect for them.
OTOH - the OEM Onan is a picture of simplicity - the prime mover is a rock solid, 8000 hour design that will last far longer than that with just basic care and perhaps a crank seal every couple of decades. The wasted-spark ignition system is dirt simple (what could be simpler than breaker point ignition?) and the fuel delivery and carburetion system is about the most trivial design possible. The starter is simple to work on and can be completely rebuilt by an amateur mechanic for less than $15 in parts. And that’s not to mention how much quieter it is at 1800RPM...
IMO the two things that every Onan should have done to it:
1. At a very minimum - immediately overhaul the breaker point ignition system and LEARN HOW IT WORKS. Better yet, replace it with Onan’s electronic ignition module. Best of all: Pertronix (but if you do a Pertronix, keep the breaker points in place as a backup and learn how to hook it back up - it is only one wire that needs reconnected). This latter hint saved my bacon on a trip one time when my pertronix mount broke off.
2. If you have an OEM control board then get rid of it and replace with a Dino. I’ve worked in the electronics design and testing business long enough to know that the OEM boards are on borrowed time and Murphy will fail yours when you need it most. If you can’t bring yourself to buy a Dino then buy two alligator clip leads and learn how to jumper battery+ to coil+ with one of them and then jog the starter with the other - the engine is more than capable of running without any control board in this manner.
The other observation I’ve made is that people panic when their onan acts up and they immediately start flailing around - hoping in desperation that they’ll find a solution by trying random things - jumping this pin to that, de-carboning heads, tearing into the carb before confirming that there’s enough fuel in their tanks, etc. The only way to solve Onan problems is methodically - a step at a time - by ruling out only a few potential problem sources.
The only other aspect of the Powerdrawer is the alternator section - of which most all problems can be solved. Just like the prime mover, the alternator is a dirt-simple design with only two semiconductor components in it - one of which is trivial to replace and other I’ve never seen go bad on any unit. The alternator, due to its simplicity - is FAR less likely to let you down than a system with a complex excitation and voltage regulation system.
—Jim
Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: [GMCnet] Onan Adventures [message #318466 is a reply to message #318457] |
Sun, 04 June 2017 13:40 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Jim,
I totally agree and have always thought that the Onan was a far superior unit compared to all other offerings. I guess the main issue for most people is reliability which can be kind of sketchy if the machine has not been maintained correctly.
Again, the ONLY reason I replaced my old, high hour machine was that I got a great deal on this 'fully reconditioned' one. I hope it was the right decision because it was a LOT of work.
One thing I had happen, that kind of puzzled me, was that under the initial testing, it would handle the load of both air conditioners and the water heater, but yesterday, after running it for about half an hour, it would bog down when the second AC unit came in. The only difference was that I had adjusted the carburetor a little richer. Upon further investigation, I found that it would handle the additional load if I leaned out the carb to the point of 'lean best mixture'. What was happening is that the governor was opening the throttle and the engine was loading up instead of just taking the load and then evening out again. Am I missing something, or did I just screw up the carb adjustment?
This new unit has an electric fuel pump that puts out 5 -9 PSI. Is that too much pressure? Could that be causing it to run a little rich? It also has the Onan electronic ignition on it, and starts instantly.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Onan Adventures [message #318472 is a reply to message #318466] |
Sun, 04 June 2017 14:01 |
Jim Miller
Messages: 501
Registered: March 2008
Karma: 10
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On Jun 4, 2017, at 2:40 PM, Carl Stouffer wrote:
> I found that it would handle the additional load if I leaned out the carb to the point of 'lean best mixture'. What was happening is that the governor was opening the throttle and the engine was loading up instead of just taking the load and then evening out again. Am I missing something, or did I just screw up the carb adjustment?
I’d say you just had the carb off a little. Load it up to the max with both A/C compressors on and the electric hot water heater and then slowly adjust toward rich until it just starts to stumble - then back off perhaps 1/4 turn until it is stable. Then shut off an A/C and bring it back online 5 minutes later and see how the unit picks up the load when the compressor starts. After that test then unload the unit completely and then re-add load in increments to see how it acts.
IMO the carb adjustment isn’t too critical as long as it handles full load properly. Personally, I favor the adjustment toward rich rather than lean.
> This new unit has an electric fuel pump that puts out 5 -9 PSI. Is that too much pressure? Could that be causing it to run a little rich? It also has the Onan electronic ignition on it, and starts instantly.
I measured the OEM pumps at around 2 PSI and I think that is more than sufficient. 5-9 PSI is probably a little much - but if your machine acts OK and doesn’t have fuel pouring out the bowl vent then keep it!
—Jim
Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: [GMCnet] Onan Adventures [message #318474 is a reply to message #318472] |
Sun, 04 June 2017 14:53 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Jim Miller wrote on Sun, 04 June 2017 12:01On Jun 4, 2017, at 2:40 PM, Carl Stouffer wrote:
> I found that it would handle the additional load if I leaned out the carb to the point of 'lean best mixture'. What was happening is that the governor was opening the throttle and the engine was loading up instead of just taking the load and then evening out again. Am I missing something, or did I just screw up the carb adjustment?
I'd say you just had the carb off a little. Load it up to the max with both A/C compressors on and the electric hot water heater and then slowly adjust toward rich until it just starts to stumble - then back off perhaps 1/4 turn until it is stable. Then shut off an A/C and bring it back online 5 minutes later and see how the unit picks up the load when the compressor starts. After that test then unload the unit completely and then re-add load in increments to see how it acts.
IMO the carb adjustment isn't too critical as long as it handles full load properly. Personally, I favor the adjustment toward rich rather than lean.
> This new unit has an electric fuel pump that puts out 5 -9 PSI. Is that too much pressure? Could that be causing it to run a little rich? It also has the Onan electronic ignition on it, and starts instantly.
I measured the OEM pumps at around 2 PSI and I think that is more than sufficient. 5-9 PSI is probably a little much - but if your machine acts OK and doesn't have fuel pouring out the bowl vent then keep it!
--Jim
Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH
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Thanks Jim. I'll follow that procedure. I thought it would run better on the slightly rich side too, but it doesn't. The carb does not have fuel pouring out the fuel vent, so I guess it's OK. My old one has a low pressure Mr Gasket pump on it after the stock pump slowly failed. I think I'll pick one of those up as a spare and if it acts up, I'll install the lower pressure one.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Onan Adventures [message #318476 is a reply to message #318457] |
Sun, 04 June 2017 15:10 |
Richard Denney
Messages: 920
Registered: April 2010
Karma: 9
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Senior Member |
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Jim, I feel this need to defend the decisions of those who replaced their
Onans. There really are quite a lot of people who were more than systematic
in their attempts to make the Onan reliable, and still invested more time
in it than anything else on the coach only to find that it had simply
suffered too much neglect to ever work reliably.
I replaced mine before the oil leaking from the crank seals caught fire on
the muffler, or the exhaust jet from the crack in the exhaust manifold
charred all the way through the wood compartment (instead of just partway
through), or some other unknown problem appeared after spending the dollars
and hours to correct those problems. Bringing a high-hour, long-neglected
Onan up to a state of good repair so that it will be reliable is a hobby in
its own right--that wasn't my hobby and I didn't have time for it to be.
Forget trying to find anyone else who will actually repair it with
expertise and for a reasonable price rather than just throwing money at it
and letting me be the test facility.
Had I not had those issues, or had a 4K Onan that was really right been
reasonably available for a reasonable price, I might still be using an
Onan. But despite the one (frustrating, to be sure) issue I've had with the
Generac I installed, it's been reliable, and while I read about others
fighting strange issues with their Onans, I've been generating electricity.
I don't think removing the extra 250 pounds did the coach any harm, either.
But it certainly depends on the starting point.
I've had the Generac for a dozen years and it has all of about 130 hours on
it. 8000 hours of reliability isn't one of my requirements. :)
Rick "who didn't really want ten years of experience working on Power
Drawers" Denney
On Sun, Jun 4, 2017 at 1:59 PM Jim Miller wrote:
> On Jun 2, 2017, at 1:33 PM, Carl Stouffer wrote:
>
>> I guess the cost of a full recondition of this Onan wasn't a factor for
> Kerry, but I've often wondered why we don't see more of that going on. Are
> the parts prohibitively expensive or just not available? The Power Drawer
> was specifically designed for the GMC and is therefore a perfect fit, so it
> made sense to me, to stick with it. Besides, a new one costs ~$3500.00.
>
> I’ve worked on powerdrawers for almost 10 years now and I continue to
> marvel at the bad things people say about them and how frustrated owners
> can be - to the point of pulling out perfectly serviceable units and
> replacing them with some discontinued Honda or some other brand of 3600 RPM
> hack job. Granted, different users have different desires - some don’t care
> about noise, some don’t care about complexity and multiple failure modes -
> plus many on this list are more than capable of Macguyvering any machine to
> run in an emergency so a non-Onan is just perfect for them.
>
> OTOH - the OEM Onan is a picture of simplicity - the prime mover is a rock
> solid, 8000 hour design that will last far longer than that with just basic
> care and perhaps a crank seal every couple of decades. The wasted-spark
> ignition system is dirt simple (what could be simpler than breaker point
> ignition?) and the fuel delivery and carburetion system is about the most
> trivial design possible. The starter is simple to work on and can be
> completely rebuilt by an amateur mechanic for less than $15 in parts. And
> that’s not to mention how much quieter it is at 1800RPM...
>
> IMO the two things that every Onan should have done to it:
>
> 1. At a very minimum - immediately overhaul the breaker point ignition
> system and LEARN HOW IT WORKS. Better yet, replace it with Onan’s
> electronic ignition module. Best of all: Pertronix (but if you do a
> Pertronix, keep the breaker points in place as a backup and learn how to
> hook it back up - it is only one wire that needs reconnected). This latter
> hint saved my bacon on a trip one time when my pertronix mount broke off.
>
> 2. If you have an OEM control board then get rid of it and replace with a
> Dino. I’ve worked in the electronics design and testing business long
> enough to know that the OEM boards are on borrowed time and Murphy will
> fail yours when you need it most. If you can’t bring yourself to buy a Dino
> then buy two alligator clip leads and learn how to jumper battery+ to coil+
> with one of them and then jog the starter with the other - the engine is
> more than capable of running without any control board in this manner.
>
> The other observation I’ve made is that people panic when their onan acts
> up and they immediately start flailing around - hoping in desperation that
> they’ll find a solution by trying random things - jumping this pin to that,
> de-carboning heads, tearing into the carb before confirming that there’s
> enough fuel in their tanks, etc. The only way to solve Onan problems is
> methodically - a step at a time - by ruling out only a few potential
> problem sources.
>
> The only other aspect of the Powerdrawer is the alternator section - of
> which most all problems can be solved. Just like the prime mover, the
> alternator is a dirt-simple design with only two semiconductor components
> in it - one of which is trivial to replace and other I’ve never seen go bad
> on any unit. The alternator, due to its simplicity - is FAR less likely to
> let you down than a system with a complex excitation and voltage regulation
> system.
>
> —Jim
>
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
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| Re: Onan Adventures [message #318477 is a reply to message #318374] |
Sun, 04 June 2017 15:55 |
SpookyEng
Messages: 208
Registered: June 2016
Location: Navarre, FL
Karma: -5
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Senior Member |
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The Onan in our coach fires right up, and has no issue carrying a load. However if you try to run it in the coach it over heats in about 5 minutes. Unfortunately the coach got hit before I was able to troubleshoot it.
JD Lisenby- USAF Ret
1978 Royale-455
MacDash, Manny Tranny, FI-tech, 3.70 etc etc
Navarre, FL
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| Re: [GMCnet] Onan Adventures [message #318690 is a reply to message #318474] |
Wed, 07 June 2017 21:58 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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I got to the bottom of the Onan running issues. I ran it again this evening, and the longer it ran, the worse it ran and the less electrical load it would take, leading me to think it was overheating. I checked the timing and it was off quite a bit. As I moved the electronic pick-up one way, it ran worse and the other way, better.
Got out the timing light and got it set to the 20 degrees BTC that it's supposed to be at, then re-set the governor speed and it ran 100% better and handled all the load I could put on it. I also took the bowl off the bottom of the carburetor and cleaned a little bit of junk out of it and made sure the jets were all clean. Crossing my fingers.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Onan Adventures [message #318706 is a reply to message #318696] |
Thu, 08 June 2017 00:16 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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hal kading wrote on Wed, 07 June 2017 22:57Carl,
With electronic ignition Ken B, IIRC, advises about 27 degrees advance for the best running Onan.
Hal Kading 78 Buskirk Las Cruces NM
I am running 26 BTDC.
The original spec for the Onan with points was 25 BTDC. Onan had a few engines returned with detonation problems and so they reduced the spec to 22 BTDC. Then in another later move they changed the spec to 20 BTDC. Depending on when your flywheel was made, you can find any one of the 3 marks. The problem was not with their timing spec. It was with the push rod operated points on it. That push rod system caused the static timing to jump all over the place causing some situations where the timing advance was more than the engine could handle. So rather than fix the mechanical points design problem, they took the cheap way out and simply reduced the timing spec.
When you replace the points with the Pertronix electronic pickup, you fix the mechanical points problem and the timing will remain stable wherever you set it.
I talked to a retired Onan engineer about 12 years ago. He is the one that gave me the above history. He also stated if the timing was stable that the Onan will easily run at 30 BTDC on 87 octane gas.
So I set mine at a conservative 26 - 27 BTDC. It has been this way for about 12 years with a Pertronix ignition installation.
Do not do set the timing above spec if you have one of the Onan solid state ignitions. That Onan system still uses the push rod and has the stability problem.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
[Updated on: Thu, 08 June 2017 00:21] Report message to a moderator |
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| Re: [GMCnet] Onan Adventures [message #318713 is a reply to message #318706] |
Thu, 08 June 2017 08:19 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Yeah, this one has the Onan solid state ignition, so I'll stick to the Onan spec. The timing mark looked to be pretty steady though.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Onan Adventures [message #318724 is a reply to message #318713] |
Thu, 08 June 2017 12:23 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Steady, but how wide? Let me tell a tale:
On the way to Alaska in 2000, I needed new points for my then-original
4kW. When I went to an RV dealership near Whidbey Island, WA, I found that
they were closing out their Onan inventory, which included an electronic
ignition kit. That cost little more than a set of points, so I bought and
installed it. What a difference! It really did run a LOT better.
Not too long after our return from Alaska, Lawrence Gaskins, a past GMCer
from WV, came up with the idea of using the Pertronix ignition triggered by
a magnet on the flywheel. Several of us, intrigued by the uniqueness of
the idea, possible only because of the distributorless lost-spark ignition
system, immediately followed Lawrence's lead. This album was first
published somewhat earlier than the photo site date indicates; Bobby Moore
wanted it as soon as he heard about it:
http://www.gmcmhphotos.com/photos/g3608-onan-ignition-upgrade-to-pertronix.html
One of the first things we noticed was that the timing mark with either of
the original ignition systems was a blur 1/4+" wide. On some Onans there
would be an occasional flash well outside that blur -- those ran very
badly. With Lawrence's mod installed, the timing mark was exactly the same
width with the engine running or not. That was enough to convince me that
the push rod operation of the OEM systems was introducing an erratic delay
in the timing function.
I, too, have talked to the GMCer (whose name I can't recall) mentioned by
Ken B., who was the Chief Engineer on the NH project. He agreed with our
hypothesis, and told me the same story he told Ken B. about the changes in
the timing spec.
So, keep an eye on that timing mark. If it starts to widen, at least clean
the bore where the push rod rides; changing the oil might help too. Better
yet, spend the few bucks and hour or so installing the Pertronix 1181 (same
as used for the Olds 455).
Ken H.
On Thu, Jun 8, 2017 at 9:19 AM, Carl Stouffer wrote:
> Yeah, this one has the Onan solid state ignition, so I'll stick to the
> Onan spec. The timing mark looked to be pretty steady though.
> --
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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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| Re: [GMCnet] Onan Adventures [message #318733 is a reply to message #318724] |
Thu, 08 June 2017 14:45 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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I tried installing the pertronix system on my old generator. Something, either operator error (likely) or some quirk with my particular generator, or maybe the way it was wired, burned out the pertronix unit immediately (two times). The experience cost me a fair amount of money and a lot of time, and left me frustrated and disappointed. Probably just me being too dumb to make it work, but still the same result. I will just stick to the Onan Solid State ignition system (for now at least).
I will double check the timing this weekend and call it good.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Onan Adventures [message #318738 is a reply to message #318733] |
Thu, 08 June 2017 16:11 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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Call bovie, he has experience with these issues.
On Thu, Jun 8, 2017 at 12:46 PM Carl Stouffer wrote:
> I tried installing the pertronix system on my old generator. Something,
> either operator error (likely) or some quirk with my particular generator,
> or
> maybe the way it was wired, burned out the pertronix unit immediately (two
> times). The experience cost me a fair amount of money and a lot of time,
> and left me frustrated and disappointed. Probably just me being too dumb
> to make it work, but still the same result. I will just stick to the Onan
> Solid State ignition system (for now at least).
>
> I will double check the timing this weekend and call it good.
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
> Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive,
> Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American
> Eagles,
> Solar battery charging. GMCSJ and GMCMI member
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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