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Onan Generators

Onan 2.7AJ-1P/12020M new to me generator


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  #1  
Old 11-21-2016, 09:53:01 PM
77Impala 77Impala is offline
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Default Onan 2.7AJ-1P/12020M new to me generator

I have a Onan 2.7AJ-1P/12020M generator serial # G760155415. I am looking for any and all information available for it such as parts, owners, repair, and wiring manuals and such. Also where to find parts for this critter. I know it needs motor mounts. I will send my email by PM upon request.

I need to take more pics of it for all I have is the name plate information pics I took. But the unit is from an old RV from about 1955 or 1956 from what I have gathered from the serial number. It is currently on a homemade 3 wheel cart with a battery box. I need to replace the battery box and add a fuel tank which I have from a china made blown generator that I found had a burnt armature before I acquired it.

Before I start it I will be getting a battery for it and see if I can clean the armature and brushes or see about replacing the brushes. It appears to have three sets of brushes, but I am not sure.

From what I have been told it ran last about 2 years ago and may have been loaded up to 4kw. That is 1.3kw more than the little critter is rated for and had been run that hard for about 8 hours.

My plans are to use it for power outages to run the fridge and one window AC plus phone/tablet chargers and recharge my ham radio station back up battery. And use it when doing yard work to power my AC powered yard tools such as electric chain saw and pole saw.

Appreciate any and all help on this.

---------- Post added at 07:53:01 PM ---------- Previous post was at 07:50:44 PM ----------

Forgot to add that I will also do an oil change and replace the spark plug before starting it.
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Old 11-21-2016, 10:08:00 PM
yellowlister yellowlister is offline
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Default Re: Onan 2.7AJ-1P/12020M new to me generator

Built 7 of 76.. good tiny loud generators perfect for a tight spot in a rv.. other than that. Be careful removing the brush holders as there a hard type of plastic and can pop there your sol.. as I found out the hard way.. I have one that runs but the gen stator has alot of rust damage and will not make voltage..

I do not think you can buy brushes.. will have to have them.made.. but may be able to find some from onanparts.com or from ebay..

I.would not.be to.worried about it being loaded up to 4kw.. it will do it, or it will shut down.. or.possibly overheat the windings on the gen.. but you will have to.ohm the windings out or just start it and see what happens

Same thing with motor mounts.. can probably find some similar from mcmaster carr.

You can find manuals from http://www.twinslan.net/~n0nas/manuals/onan/
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Old 11-21-2016, 10:11:44 PM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Onan 2.7AJ-1P/12020M new to me generator

It was made in July 1976. Can pull around 25 amps. Might pull 4 for a very short time. But not for eight hours. Sending the wiring print. Go to twinslan.net onan for the manuals.
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Old 11-22-2016, 08:25:47 AM
77Impala 77Impala is offline
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Default Re: Onan 2.7AJ-1P/12020M new to me generator

Thanks guys, I printed out the wiring schematic. And will look into the manuals later today or by the end of the week.

On the last owner run on it the RV's AC and fridge plus lights and TV were on all the time and the microwave here and there. So I can see the 4kw being only part time.

I will leave the brushes alone for now and see what she can do when I am ready to start her up. And I am fair at custom engineering so I will see what I can do for new motor mounts.
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Old 11-24-2016, 07:38:29 PM
77Impala 77Impala is offline
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Default Re: Onan 2.7AJ-1P/12020M new to me generator

Here are a few pics of the generator.




And the fuel tank I will be installing on top of the cart.


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Old 07-01-2017, 09:57:24 PM
77Impala 77Impala is offline
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Default Re: Onan 2.7AJ-1P/12020M new to me generator

Well an update that is long overdue. Not ready to start it back up yet. I did have to order new motor mounts for all four of the originals were sheared. I have removed the old ones but need to get a a-frame to help lift the gen set as I mount the new ones. I acquired a battery for it that is in decent shape. And I have most of the parts I need to mount and hook up the new fuel tank for it.

Forgot that I have replaced the air filter as well.
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Old 07-02-2017, 11:19:33 AM
Max Thompson Max Thompson is offline
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Default Re: Onan 2.7AJ-1P/12020M new to me generator

Quote:
Originally Posted by 77Impala View Post
I acquired a battery for it that is in decent shape.
The AJs are exciter cranked, they take a pretty good battery to spin them over.
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Old 07-02-2017, 11:23:12 AM
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Default Re: Onan 2.7AJ-1P/12020M new to me generator

Do not tighten the motor mounts down to much. There needs to be some movement. To tight and things break.

I used to go up your way all the time. Loews HighPort,Catfish Bay,Soldiers Creek and a few more I can't think of. Is there any open land between Texoma and Dallas. When I left up there 75 was a nightmare and the towns were growing together.
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Old 07-02-2017, 11:52:32 PM
77Impala 77Impala is offline
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Default Re: Onan 2.7AJ-1P/12020M new to me generator

There is some land left between Sherman and McKinney. But things are growing pretty quickly. Highway 75 is still widening out north of McKinney. Highway 289 will take you directly from Highway 380 all the way up to Lowes High Port Mariana now.
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Old 08-11-2017, 06:53:40 PM
77Impala 77Impala is offline
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Default Re: Onan 2.7AJ-1P/12020M new to me generator

First I need to say sorry to anyone who wants to see pics of my progress. Photobucket decided that I needed to pay them $40.00 a month to allow my pictures to be view on the forums I sometimes frequent and that is not worth it to me at all.

With that said my progress so far is that I have the new motor mounts installed and I did have to use a battery boost charger to get the gen to turn over. Have not added fuel to the mix yet because I wanted to first know if the engine would still turn since I found very little oil in the crank case. Also with the heat and my work I did not have time or energy to proceed from there.

I did talk to the previous owner and he did inform me that the last time he had the motor running that it did not make power. I am concerned about that.

I have not installed the fuel tank yet but will run a gas line to a fuel can to get the gen running and see what voltages it can make. The time he did over run the power it was still producing power when he shut it down. And did not make power on the next restart after that.
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Old 08-12-2017, 12:40:54 PM
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Default Re: Onan 2.7AJ-1P/12020M new to me generator

Well sad news, the brushes on the 120 volt side are bad. Only got 50 volts ac. Lots of sparking going on on the armature. I have a video of it running 300 watts of work lights and no stability on the out put. On the 12 volt dc side it only produced 12.7 volts of charging power back to the battery. Don't know if that is good or not since I still had to use the battery booster to get the gen set started.

Due to lack of available parts such as the brushes and brush caps I am done with this one. If anyone is interested and wants to pick it up you can PM me. Asking $40.00 to help cover parts I have bought for it (motor mounts, air filter, bolts, nuts, washers for fuel tank mounting). I would include the fuel tank from a previous gen set. No battery.
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