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Onan Generators

Onan 2.5LK-1R Cranking Problem


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  #1  
Old 06-14-2013, 09:04:20 AM
8 Lugs 8 Lugs is offline
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Default Onan 2.5LK-1R Cranking Problem

Hello,
About 12 or 13 years ago I purchased a well used 82 Ford F350 equipped with a Versalift aerial bucket lift/ Reading utility body on it.
After quite a bit of work on the truck and lift everything worked pretty well, good enough for tree and home repairs around the house.
The Onan Genset is the type that has the shaft sticking out of the generator that turns the lift's hydraulic pump for the bucket's operation. It can be started either by a toggle switch on the Genset or remotely from the buckets control panel.
To start the Onan motor, 12 volts is sent from the Genset battery via the set's starting solenoid into the generator turning it into a motor. After starting the engine the switch is released and the Genset puts out 120 volts to the lift's outlets. It has never put 12+ volts back into it's battery after starting and was connected in parallel to the Ford trucks battery, supposedly for the Gensets operational longevity because the Onan motor and the bucket's controls run on 12 volts. This was never a problem for me because I only use it is my yard.
Well, this spring I installed known good batteries in the truck and lift, and went to start the Genset. It cranked very slowly, too slow to start the motor. Pulling the belt off of the lift's drive from the Genset, the motor/ generator turned freely. I pulled the Genset's cover to access the cables going directly into the generator/ motor and measured 11+ volts while cranking at the leaving side of the solenoid and the Genset's metal housing. I connected my HD battery charger onto the battery and switched it to 250 amp start. Putting 15+ volts into the motor/ generator did not, at all increase cranking speed. I pulled the spark plug and it almost came up to normal speed. The only lead that was getting warm was the one from the solenoid into the motor however, not hot enough to even start to smell. Inspecting to brushes in the motor/ generator, I'm going to guess they are about half of the length they started life at and the commutator's notches are getting shallow.
Would anyone out there have any suggestions as to what would be my next move to correct this problem just shy of giving it a proper burial?

Onan Gen Set McGraw-Edison
m. 2.5LK-1R/23436L
s.3820

Thanks,

Steve G.
Easthampton, Ma.
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  #2  
Old 06-14-2013, 09:18:15 AM
Kpack
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Default Re: Onan 2.5LK-1R cranking problem

If you need the service manual for troubleshooting and specs on gen post your email and someone will send it to you. Your problem could be several things I would start by setting the valves to spec. The experts will be along to help you.
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Old 06-14-2013, 02:37:11 PM
8 Lugs 8 Lugs is offline
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Default Re: Onan 2.5LK-1R cranking problem

Yes, I would really appreciate a service manual to help in troubleshooting but I don't think posting my personal email address would be wise.
Is there another way I might obtain one, maybe thru private messaging?

Steve G.
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Old 06-14-2013, 03:32:08 PM
Kpack
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Default Re: Onan 2.5LK-1R cranking problem

Yes you could pm me
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Old 06-15-2013, 11:54:33 AM
Kpack
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Default Re: Onan 2.5LK-1R cranking problem

I've sent you a back private message
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  #6  
Old 06-15-2013, 12:53:26 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 2.5LK-1R cranking problem

Cleaning the commutator where the brushes contact it would be a good start. I will assume the brushes are free in their holders & making good contact with the commutator. Just to eliminate the possibility of a short somewhere, I would also disconnect the output wires form the generator. If there is an electrical load on it while trying to start, it will make it slow to crank. Check the battery cable connections, including the ground wire & if it has one, the ground strap to the frame. As you have found, it takes a bunch of amps to turn the LK past the compression stroke.

Kpack should have the service manual now.
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  #7  
Old 06-16-2013, 09:10:32 AM
Kpack
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Default Re: Onan 2.5LK-1R cranking problem

930-0501 service manual sent
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  #8  
Old 06-19-2013, 10:42:06 AM
8 Lugs 8 Lugs is offline
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Default Re: Onan 2.5LK-1R cranking problem

Thanks Kpack for the service manual. I really appreciate that!
My home computer absolutly refuses to open the file and I am on "Staycation" this week, trying to accomplish my usual 400 tasks I set out to do. When I go back to work next week I will open and print it there.

Also a thanks to Max for the advice!
I had eliminated all of the cables by connecting everything at the motor/ generator where the main positive lead goes into the motor housing, monitoring voltage as it was slowly turning over. It really didn't appear to be drawing much current and took several attempts to get the main positive lead to get warm, almost as if there was another winding that was not being energized.
Hopefully by Friday or Saturday I will have some time to pull the sheave and brushes end off of it and take some sand cloth to the commutator as you suggested. Maybe take a modified hacksaw blade and make the notches a bit deeper.

Again, Thanks for your help and I will let you know how I make out!

Steve G.
Easthampton, Ma.
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  #9  
Old 06-19-2013, 12:28:47 PM
Kpack
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Default Re: Onan 2.5LK-1R cranking problem

https://www.dropbox.com/s/q3a1g5vbc5...%20SERVICE.pdf
See if you can open this . I sent the other staight from the one max sent me.
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  #10  
Old 06-24-2013, 01:23:59 PM
8 Lugs 8 Lugs is offline
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Default Re: Onan 2.5LK-1R cranking problem

I was able to download and print the manual successfully at work.
40 pages of great information, thank you VERY MUCH!
I will let you know how I make out.

Steve G.
Easthampton, Ma.
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