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| Onan [message #112458] |
Thu, 20 January 2011 08:13  |
2-4 the road
Messages: 145
Registered: June 2009
Location: Fulltimers
Karma: 0
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Senior Member |
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This will be my last post on this topic unless it is to say fixed!
Review: Onan runs quiet and smooth for the first 15-20 mins. then dies. On restarts it dies after 3-4 secs. Seems hot.
We have the paper manuals and Tom Lins' CD and have went through everything in them.
In the last year we have replaced the board, fuel pump, fuel lines, spark plugs,air filter and air cleaner, changed oil, exhaust system with extended tail pipe (onan ran fine the first 5 days out)Cleaned and set point gap ( no access to new) and fine tuned the fuel mix. Shrouding has been removed to check for nests or anything that might impede cooling.
Oil is checked before each start and we bypassed the LOP switch in our trouble shooting efforts.
Any new suggestions before it hits the ocean (we are in the Everglades).
JoAnne
2-4 the road
77 Kingsley 455
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| Re: [GMCnet] Onan [message #112464 is a reply to message #112458] |
Thu, 20 January 2011 08:48  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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JoAnne,
The Onan in Double Trouble ran great the first year we had it. The second
year it started out OK but developed the same problem yours has. While I was
at Tom Hamptons up in Ohio we trouble shot the thing and found that the coil
was breaking down when it got hot.
Go a local Harley shop (preferably an aftermarket type shop not a Harley
dealership) and ask them if they have any second hand 12vdc coils to sell.
Harleys coils have two spark plug leads on them and they fire the plugs at
the same time. It's called a waste spark system. The coil fires the cylinder
on the compression stroke and the other cylinder on the exhaust stroke.
One of the common mods to the ignition system is to convert to a "single
fire" ignition system. Those systems use a special ignition module and two
coils siamesed together, however, each one fires one plug only.
You should be able to get one cheap. A new replacement coil from Onan is
REALLY expensive and it is not a bolt in replacement. You'll have to do a
bit of minor engineering to attach the HD coil too.
Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of JoAnne Bissell
Sent: Friday, January 21, 2011 1:13 AM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] Onan
This will be my last post on this topic unless it is to say fixed!
Review: Onan runs quiet and smooth for the first 15-20 mins. then dies. On
restarts it dies after 3-4 secs. Seems hot.
We have the paper manuals and Tom Lins' CD and have went through everything
in them.
In the last year we have replaced the board, fuel pump, fuel lines, spark
plugs,air filter and air cleaner, changed oil, exhaust system with extended
tail pipe (onan ran fine the first 5 days out)Cleaned and set point gap ( no
access to new) and fine tuned the fuel mix. Shrouding has been removed to
check for nests or anything that might impede cooling.
Oil is checked before each start and we bypassed the LOP switch in our
trouble shooting efforts.
Any new suggestions before it hits the ocean (we are in the Everglades).
JoAnne
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Onan [message #112475 is a reply to message #112458] |
Thu, 20 January 2011 09:42 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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JoAnne,
Mine had the same issue and it absolutely kicked Mr. Onan's butt a few
years ago at a rally. Would run perfect for a while, then shut down. Start
& run perfect, then shut down. After about 4 hours, Duane called it quits.
I got it home, adjusted the timing and it has never had a problem since. I
have no explanation for it's behavior and it flies in the face of common
sense, but that's what it was. It had the Pertronix unit installed at the
time.
On Thu, Jan 20, 2011 at 7:13 AM, JoAnne Bissell <joanne.bissell@gmail.com>wrote:
>
>
> This will be my last post on this topic unless it is to say fixed!
> Review: Onan runs quiet and smooth for the first 15-20 mins. then dies. On
> restarts it dies after 3-4 secs. Seems hot.
> We have the paper manuals and Tom Lins' CD and have went through everything
> in them.
> In the last year we have replaced the board, fuel pump, fuel lines, spark
> plugs,air filter and air cleaner, changed oil, exhaust system with extended
> tail pipe (onan ran fine the first 5 days out)Cleaned and set point gap ( no
> access to new) and fine tuned the fuel mix. Shrouding has been removed to
> check for nests or anything that might impede cooling.
> Oil is checked before each start and we bypassed the LOP switch in our
> trouble shooting efforts.
> Any new suggestions before it hits the ocean (we are in the Everglades).
> JoAnne
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Steve Ferguson
Sierra Vista, AZ
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| Re: [GMCnet] Onan [message #112485 is a reply to message #112475] |
Thu, 20 January 2011 10:39 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Steve,
Was that the Onan-labeled Pertronix or the Gaskins mod using a standard
Pertronix?
Ken H.
On Thu, Jan 20, 2011 at 10:42 AM, Steven Ferguson wrote:
> JoAnne,
> Mine had the same issue and it absolutely kicked Mr. Onan's butt a few
> years ago at a rally. Would run perfect for a while, then shut down.
> Start
> & run perfect, then shut down. After about 4 hours, Duane called it quits.
> I got it home, adjusted the timing and it has never had a problem since. I
> have no explanation for it's behavior and it flies in the face of common
> sense, but that's what it was. It had the Pertronix unit installed at the
> time.
>
>
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List Information and Subscription Options:
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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 [message #112496 is a reply to message #112458] |
Thu, 20 January 2011 11:42 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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On Jan 20, 2011, at 7:13 AM, JoAnne Bissell wrote:
> This will be my last post on this topic unless it is to say fixed!
> Review: Onan runs quiet and smooth for the first 15-20 mins. then dies. On restarts it dies after 3-4 secs. Seems hot.
> We have the paper manuals and Tom Lins' CD and have went through everything in them.
> In the last year we have replaced the board, fuel pump, fuel lines, spark plugs,air filter and air cleaner, changed oil, exhaust system with extended tail pipe (onan ran fine the first 5 days out)Cleaned and set point gap ( no access to new) and fine tuned the fuel mix. Shrouding has been removed to check for nests or anything that might impede cooling.
> Oil is checked before each start and we bypassed the LOP switch in our trouble shooting efforts.
> Any new suggestions before it hits the ocean (we are in the Everglades).
> JoAnne
Electrical connections sometimes go bad when they heat up. I would suggest that you first check you oil level and make sure that it is full. Then attach a lead from terminal 9 to terminal 5 on your control panel that is mounted on the side of the Onan. This bypasses the control board and also the oil pressure safety switch. That is why you must check your oil level first.
Start and run the Onan. If it will now run for more than the 20 minutes and not die you probably have a connection on the control board that is loose or corroded. It could also be a capacitor on the control panel. These will also sometimes open when they heat up.
If you find out its the control panel you can get one from Jim Kanomata or have Duane Simmons swap it out with a rebuilt one. I believe that Jim gets them from Duane.
If it still cuts out when running for over 20 minutes then I would suggest that you check all the other terminals. Here is part of a message that I posted in 2001:
------------------------------
While under the Onan I accidentally discovered that a lead going to the rectifier was very loose at a connection and would not hold together. There are two male/female spade connectors going from the field windings to the + and - terminals of the rectifier. Each set is in its own approximately 2" long plastic insulating tube. The connectors are made of brass and I found that there was very poor contact as the brass female connector had lost its tension. When it would heat up it would lose its connnection. I attempted to squeeze it with some needle nose pliers and it immediately cracked. I then soldered in a new steel female connector, coated it with dielectric grease and plugged in back to the male connector in the tube. I checked the other connector and found that it also was making very poor connection and was also loose in the tube. I replaced that connector as well.
I then noticed a paragraph in the maintenance manual about the linkage adjustment (from the carb throttle to the ball on the governor arm). I had never adjusted that so I decided to check it. Following the instructions, with the Onan off, I popped it off the ball joint and held the carb wide open against its stop and checked the end against the ball joint. I found the linkage to be about 1/4" too long. I rotated the end until it just fit over the ball stud. I then restarted the Onan and readjusted the carb and governor until I again had 126 volts at no load. I then started to turn on electrical equipment and found that the voltage never dropped below 120 volts. I started with the water heater, added the coffee pot, the air conditioner heat strip and even the microwave and it would still hold at 120 volts. I calculate that I had about a full load of 6000 watts on the Onan. It has never done this before in the 20+ years that I've had the GMC.
I had never thought to adjust the linkage arm before. In fact, the factory paint was still on the threads when I turned the end to shorten it. It apparently had never been set properly by the factory.
I also noticed that there are two more of the connectors in the same type sleeves on the left top of the Onan in the wires going to the fuel pump and to the solenoid. I checked these but they were tight. Apparently the heat from the engine and generator caused the lower brass field wire connectors to loose their temper and thus cause a loose connection.
I would suggest that everyone check these two connectors and the carb linkage on their Onan. There was nothing wrong with the compounding reactor. I believe that my initial problem was occurring because of intermittent contact on the field windings.
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: [GMCnet] Onan [message #112503 is a reply to message #112496] |
Thu, 20 January 2011 12:22 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Onan warriors, I have had considerable experience with the Onan cast iron
CCK as used in the GMC as well as the Aluminum block BF engines used in many
garden tractors. I have found more than a few failed ignition coils on both
models. The symptoms are similar. The engine will start fine when cold and
run well enough until a heavy load is placed on it and the coils become
heated up. The engine will surge and pull hard against the governor and
eventually quit. No amount of coaxing will convince it to run until it is
cooled off. Behaves very much like an out of gas or vapor lock situation.
Cummins/Onan is very proud of their ignition coils. I have not checked
lately, but company Napa stores used to carry a line of small engine parts
and listed a replacement coil for the Onan twins at a more acceptable price.
A simple test is to take an old sparkplug and either hose clamp or weld a
large alligator clip onto the metal body of the plug and then open up the
electrode gap to about .100". Clip the plug to a place where it can be
visually observed, attatch either spark plug lead to the plug and crank the
engine. If it will jump the .100" gap in open air, it should work in the
engine and you can rule out a failed coil. These engines are sensitive to
oil residue on the points as well, and the pertronics module will solve that
problem. Be advised, the pertronics modules can and do fail as well. The
spark check will verify whether the problem is electical related in any
case. JWID
Jim Hupy
Salem, OR
78 GMC Royale 403
On Thu, Jan 20, 2011 at 9:42 AM, Emery Stora <emerystora@mac.com> wrote:
>
> On Jan 20, 2011, at 7:13 AM, JoAnne Bissell wrote:
>
> > This will be my last post on this topic unless it is to say fixed!
> > Review: Onan runs quiet and smooth for the first 15-20 mins. then dies.
> On restarts it dies after 3-4 secs. Seems hot.
> > We have the paper manuals and Tom Lins' CD and have went through
> everything in them.
> > In the last year we have replaced the board, fuel pump, fuel lines, spark
> plugs,air filter and air cleaner, changed oil, exhaust system with extended
> tail pipe (onan ran fine the first 5 days out)Cleaned and set point gap ( no
> access to new) and fine tuned the fuel mix. Shrouding has been removed to
> check for nests or anything that might impede cooling.
> > Oil is checked before each start and we bypassed the LOP switch in our
> trouble shooting efforts.
> > Any new suggestions before it hits the ocean (we are in the Everglades).
> > JoAnne
>
> Electrical connections sometimes go bad when they heat up. I would suggest
> that you first check you oil level and make sure that it is full. Then
> attach a lead from terminal 9 to terminal 5 on your control panel that is
> mounted on the side of the Onan. This bypasses the control board and also
> the oil pressure safety switch. That is why you must check your oil level
> first.
>
> Start and run the Onan. If it will now run for more than the 20 minutes
> and not die you probably have a connection on the control board that is
> loose or corroded. It could also be a capacitor on the control panel.
> These will also sometimes open when they heat up.
>
> If you find out its the control panel you can get one from Jim Kanomata or
> have Duane Simmons swap it out with a rebuilt one. I believe that Jim gets
> them from Duane.
>
> If it still cuts out when running for over 20 minutes then I would suggest
> that you check all the other terminals. Here is part of a message that I
> posted in 2001:
> ------------------------------
>
> While under the Onan I accidentally discovered that a lead going to the
> rectifier was very loose at a connection and would not hold together. There
> are two male/female spade connectors going from the field windings to the +
> and - terminals of the rectifier. Each set is in its own approximately 2"
> long plastic insulating tube. The connectors are made of brass and I found
> that there was very poor contact as the brass female connector had lost its
> tension. When it would heat up it would lose its connnection. I attempted
> to squeeze it with some needle nose pliers and it immediately cracked. I
> then soldered in a new steel female connector, coated it with dielectric
> grease and plugged in back to the male connector in the tube. I checked the
> other connector and found that it also was making very poor connection and
> was also loose in the tube. I replaced that connector as well.
>
> I then noticed a paragraph in the maintenance manual about the linkage
> adjustment (from the carb throttle to the ball on the governor arm). I had
> never adjusted that so I decided to check it. Following the instructions,
> with the Onan off, I popped it off the ball joint and held the carb wide
> open against its stop and checked the end against the ball joint. I found
> the linkage to be about 1/4" too long. I rotated the end until it just fit
> over the ball stud. I then restarted the Onan and readjusted the carb and
> governor until I again had 126 volts at no load. I then started to turn on
> electrical equipment and found that the voltage never dropped below 120
> volts. I started with the water heater, added the coffee pot, the air
> conditioner heat strip and even the microwave and it would still hold at 120
> volts. I calculate that I had about a full load of 6000 watts on the Onan.
> It has never done this before in the 20+ years that I've had the GMC.
>
> I had never thought to adjust the linkage arm before. In fact, the factory
> paint was still on the threads when I turned the end to shorten it. It
> apparently had never been set properly by the factory.
>
> I also noticed that there are two more of the connectors in the same type
> sleeves on the left top of the Onan in the wires going to the fuel pump and
> to the solenoid. I checked these but they were tight. Apparently the heat
> from the engine and generator caused the lower brass field wire connectors
> to loose their temper and thus cause a loose connection.
>
> I would suggest that everyone check these two connectors and the carb
> linkage on their Onan. There was nothing wrong with the compounding
> reactor. I believe that my initial problem was occurring because of
> intermittent contact on the field windings.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Onan [message #112509 is a reply to message #112463] |
Thu, 20 January 2011 13:36 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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On Jan 20, 2011, at 7:47 AM, George Zhookoff wrote:
>
>
> [quote In the last year we have replaced the board, fuel pump, fuel lines, spark plugs,air filter and air cleaner, changed oil, exhaust system with extended tail pipe (onan ran fine the first 5 days out)Cleaned and set point gap ( no access to new) and fine tuned the fuel mix. Shrouding has been removed to check for nests or anything that might impede cooling.
> Oil is checked before each start and we bypassed the LOP switch in our trouble shooting efforts.
> Any new suggestions before it hits the ocean (we are in the Everglades).
> JoAnne[/quote]
>
> Have you tried jumping out the control board?
>
> Disclaimer: I would not run your Onan unattended with this work-a-round. This work-a-round by-passes the safety features of the board. It will NOT turn off power to the fuel pump and points if the motor stops for some reason other than the off switch. It also removes the low oil protections. Your results may vary and do not blame me! 8o
>
> Find the lower pin 6. (It is normally not used.) Use a crimp on connector to jump it to the pin right next to it. (I am pretty sure it is pin 9.) The Onan should start and run normally. It should even stop when you press "off." If the Onan runs when the board is jumped, get another new board.
>
> Also there is an rubber O ring on the main fuel carb adjustment screw. The O ring will wear out / split. Emery has the scope on replacing the O ring. Worked for me.
>
> George Zhookoff
> 78 EL II
> Atlanta
>
You can jump 9 to 6 but that bypasses the fuse in the control panel. If you jump 9 to 5 then the fuse is still in the circuit to protect things in case of an electrical short.
As to the O ring on the main jet, the original is a "square shouldered" O ring. I have found that a round O ring with 1/4" OD and 1/8" ID works fine. I have replaced many of them in other people's Onans at rallies. I carry a package of them in my GMC at all times. I just worked on someone's Onan two weeks ago that would not start at all. We checked several things and finally checked the main jet O ring. It was intact but seemed a bit loose. After putting on the new 1/4" / 1/8" O ring it started right up and ran fine. Obviously it was sucking air past the O ring and the resultant air / fuel mixture just would not allow the Onan to run. I have also found some that would start and run but run badly until that ring was replaced.
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: Onan [message #112522 is a reply to message #112458] |
Thu, 20 January 2011 16:03 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Hey Emery, what was the McMCaster PN for the o ring if in fact that is where you got them. A good item to keep a bag of and hand out as door prizes as well. John.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Onan [message #112531 is a reply to message #112528] |
Thu, 20 January 2011 18:18 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Interesting. I originally installed the Onan-labeled one in 2000, just
before getting on the ferry to Alaska. It failed a couple of years later,
at about the time Lawrence came up with his Pertronix mod, so I was about
the 1st or 2nd one to follow his lead -- thus my photo album:
http://www.gmcmhphotos.com/photos/showgallery.php?cat=3608
Ken H.
On Thu, Jan 20, 2011 at 6:53 PM, Steven Ferguson <botiemad11@gmail.com>wrote:
> Ken,
> It was the Onan.
>
> On Thu, Jan 20, 2011 at 9:39 AM, Ken Henderson <hend4800@bellsouth.net
> >wrote:
>
> > Steve,
> >
> > Was that the Onan-labeled Pertronix or the Gaskins mod using a standard
> > Pertronix?
>
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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