Onan Restoration Comments

[duane m simmons]

Arch
For an Onan that has set for several years w/o operation, I would do the
following after changing the Oil, Oil Filter & Air Filter: NOTE: DISABLE
ONAN POWER FROM ENTERING THE COACH POWER SYSTEM UNTIL VOLTAGE IS SET AT
PROPER LEVEL.
1) Remove the cover over the control board & spray all board & wire
terminals with an Electrical Cleaner (2-26 at home center, electrical
dept.). Spray all Onan wire terminals in sight. Wait for cleaner to
work, about 1 hour (WD 40 can be used, but not as good.
2) Remove carburetor to Fuel pump hose. File off brass crimp sleeve &
find barb fitting. Replace w/fuel hose (3/16" I Think).
3) Remove Carburetor & clean (Existing gaskets should be OK to reuse).
4) Clean all Onan Battery cables, both ends.
5) Now that the cleaner has had time to work, it is time to evaluate if
you fuel system is functional. Jumper board terminal 9 to 5 & you should
hear fuel pump & see fuel coming from pump. Got to achieve this step
before anything else (Need Fuel to function).
6) For test purpose, remove the following wires from the Control Board:
All wires on upper board terminals & terminal 12.
7) Reassemble fuel line & carburetor & jumper board terminal 9 to 5 &
let pump operate for a few seconds. Hit the start button & she should
run.
8) Adjust carburetor Hi speed jet (lower side of bowl) for smooth
running. Monitor the Onan output voltage & adjust the Governor shaft nut
for 125 to 125 V AC w/o load.

Now you should be ready to connect Onan Power to coach for evaluation
under load.

Hope this helps you get started on Onan restoration
Duane Simmons
714-633-4731

 

[bdub]

Hi Duane

Great list!

Please do continue with part 2: ...connect Onan Power to coach for
evaluation under load.

Thanks
bdub

>Arch
>For an Onan that has set for several years w/o operation, I would do the
>following after changing the Oil, Oil Filter & Air Filter: NOTE: DISABLE
>ONAN POWER FROM ENTERING THE COACH POWER SYSTEM UNTIL VOLTAGE IS SET AT
>PROPER LEVEL.
>1) Remove the cover over the control board & spray all board & wire
>terminals with an Electrical Cleaner (2-26 at home center, electrical
>dept.). Spray all Onan wire terminals in sight. Wait for cleaner to
>work, about 1 hour (WD 40 can be used, but not as good.
>2) Remove carburetor to Fuel pump hose. File off brass crimp sleeve &
>find barb fitting. Replace w/fuel hose (3/16" I Think).
>3) Remove Carburetor & clean (Existing gaskets should be OK to reuse).
>4) Clean all Onan Battery cables, both ends.
>5) Now that the cleaner has had time to work, it is time to evaluate if
>you fuel system is functional. Jumper board terminal 9 to 5 & you should
>hear fuel pump & see fuel coming from pump. Got to achieve this step
>before anything else (Need Fuel to function).
>6) For test purpose, remove the following wires from the Control Board:
>All wires on upper board terminals & terminal 12.
>7) Reassemble fuel line & carburetor & jumper board terminal 9 to 5 &
>let pump operate for a few seconds. Hit the start button & she should
>run.
>8) Adjust carburetor Hi speed jet (lower side of bowl) for smooth
>running. Monitor the Onan output voltage & adjust the Governor shaft nut
>for 125 to 125 V AC w/o load.
>
>Now you should be ready to connect Onan Power to coach for evaluation
>under load.
>
>Hope this helps you get started on Onan restoration
>Duane Simmons
>714-633-4731

 

[olin r. boyer]

Speaking of evaluation under load ---

My Onan has just been gone over (60 hours or so ago) by
bona-fide Onan professionals at Emergency Power Systems here
in Tulsa. In addition to installing a new starter bracket,
they put some parts in the carburetor, o-rings etc. and also
pulled it apart and did what they called a "de-carb" on the
engine. I had them install an electronic ignition kit, and I
think they may have "knurled the valves" (or the valve
guides! -- whatever it is that they knurl to relieve a
little "slop" in the fit!).

The technician who worked on it told me that it was really a
remarkable piece of machinery. He said that it was really
conservatively rated, and just might put out as much as 8K
if you really needed to call on it to do that. Not too many
of the new units, including the Marquis that would really
out perform the old "Power in a tray".

I would very much like to see the next chapter of
"Restoration Comments", because I am having a problem with
evaluation under load.

The unit starts well, after cranking a while to allow the
electric fuel pump to prime the bowl. (Guess I need to
install a prime circuit with a push button). The unit
stabilizes quickly, and I can immediately switch on a roof
AC unit, which the generator seems to pick right up. With
one roof AC and the inverter/charger load, it will run fine,
seemingly hour after hour. When I turn on the second roof
AC, it seems to pick it up OK, but after just two or three
minutes, it will begin to surge. When it slows, it will
usually trip one or both breakers on the AC units. Sometimes
it will continue to run after the breakers drop the load,
and sometimes it will just die completely.

After I start it back up (it seems to start quickly) I can
again load it with one roof air, but it still will not carry
two for any period of time at all.

Do I have a fuel problem or what? If Duane isn't ready with
chapter two, I'd like to hear from anyone on this problem.
Feel free to jump right in!

Olin Boyer
77GMCPB
Tulsa, Oklahoma

 

[bob mclaughlin]

Olin,
Mine was doing the heavy load surge bit. I played with the carburetor
settings and even put in a new fuel pump to no avail. I finally changed the
fuel line after finding some rubber cracking. Works great now. HTH.
Bob McLaughlin

- -----Original Message-----
From: owner-gmcmotorhome
[mailtowner-gmcmotorhome]On Behalf Of Olin R. Boyer
Sent: Sunday, July 16, 2000 9:16 PM
To: GMCnet
Subject: Re: GMC: Onan Restoration Comments

Speaking of evaluation under load ---

My Onan has just been gone over (60 hours or so ago) by
bona-fide Onan professionals at Emergency Power Systems here
in Tulsa. In addition to installing a new starter bracket,
they put some parts in the carburetor, o-rings etc. and also
pulled it apart and did what they called a "de-carb" on the
engine. I had them install an electronic ignition kit, and I
think they may have "knurled the valves" (or the valve
guides! -- whatever it is that they knurl to relieve a
little "slop" in the fit!).

The technician who worked on it told me that it was really a
remarkable piece of machinery. He said that it was really
conservatively rated, and just might put out as much as 8K
if you really needed to call on it to do that. Not too many
of the new units, including the Marquis that would really
out perform the old "Power in a tray".

I would very much like to see the next chapter of
"Restoration Comments", because I am having a problem with
evaluation under load.

The unit starts well, after cranking a while to allow the
electric fuel pump to prime the bowl. (Guess I need to
install a prime circuit with a push button). The unit
stabilizes quickly, and I can immediately switch on a roof
AC unit, which the generator seems to pick right up. With
one roof AC and the inverter/charger load, it will run fine,
seemingly hour after hour. When I turn on the second roof
AC, it seems to pick it up OK, but after just two or three
minutes, it will begin to surge. When it slows, it will
usually trip one or both breakers on the AC units. Sometimes
it will continue to run after the breakers drop the load,
and sometimes it will just die completely.

After I start it back up (it seems to start quickly) I can
again load it with one roof air, but it still will not carry
two for any period of time at all.

Do I have a fuel problem or what? If Duane isn't ready with
chapter two, I'd like to hear from anyone on this problem.
Feel free to jump right in!

Olin Boyer
77GMCPB
Tulsa, Oklahoma