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Onan 20hp issue- UPDATE


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#1 DZG OFFLINE  

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Posted September 09, 2016 - 03:18 PM

Ok guys, i got this tradesman for free and decided to hook some jumpers to it to see what would happen...

<iframe width="560" height="315" src="https://www.youtube....bed/5wcx5vlfuUo" frameborder="0" allowfullscreen></iframe>

All i got was this. It acts like a low battery, but once it gets to that point its damn near impossible to spin back by hand, then it busts free and moves good. But it only goes that far...

So...is the motor actually seized? Ive never had one seize then be able to spin ok once you roll it back...

Orrrr is it a crappy battery issue that im worrying to much about?

Or 3 is it possibly a pulley underneath, i havent unhooked the belt to try it yet, but it does it clutch in or out.

Input?

EDIT.
can someone embed my video? Im not good at that stuff

Edited by DZG, September 10, 2016 - 04:14 PM.


#2 crittersf1 OFFLINE  

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Posted September 09, 2016 - 03:30 PM

Low battery, weak starter, bad connection (ground)



#3 Eric OFFLINE  

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Posted September 09, 2016 - 03:33 PM

I agree with above, unhook pulley from it if it has belt drive and pull the plug and then turn it all the way through to see if it is seized

#4 DZG OFFLINE  

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Posted September 09, 2016 - 04:02 PM

Ok i will do that. When i yank the plugs would it be worth dumpin some atf or motor oil down in it?

#5 olcowhand ONLINE  

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Posted September 09, 2016 - 05:16 PM

Could be carbon that broke free & piled up against the head.  Sometimes backing up the piston, then back again gets it to move the carbon moved enough to get past it.  Had this happen just as you described.



#6 chieffan ONLINE  

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Posted September 09, 2016 - 05:28 PM

Look at the top of the piston through the plug hole if you can.  If it looks bad may want to pull the head and see what it really looks like in there.  If an engine has been sitting any length of time I pull the starter and check it out, lube it and most of the time if it bench checks OK I put it back on and go.  Nobody thinks about lubing a starter till they quit.  Should be done at least once a year. if it is used much.


  • Bmerf said thank you

#7 EricFromPa OFFLINE  

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Posted September 09, 2016 - 06:14 PM

Sounds like weak battery and dry starter bushings.Take the blower housing off and make sure there is no Mouse nest material and while your in there spray down the starter real good with PB Blaster or WD 40.Doesn't hurt to spray down the ring gear on the flywheel.Spraying down the ring gear Helps the starter gear retract if both are a bit rusty.

 

Heck while you have the blower housing off I would pull the heads and de-carbon the combustion chamber.

Engine could be partly seized from swelled carbon deposits.Every onan I've worked on that has sat for a few years has had rather large carbon deposits and aluminum corrosion in atleast 1 cylinder.



#8 olds45512 OFFLINE  

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Posted September 09, 2016 - 07:52 PM

I had a magnum 18 that was locked solid, turned out to be the blower housing was fill to the top with acorns.

#9 olcowhand ONLINE  

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Posted September 09, 2016 - 08:45 PM

After watching the video, I lean toward starter being in poor condition.



#10 DZG OFFLINE  

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Posted September 10, 2016 - 04:01 AM

Thanks for the input guys. Hopefully today i can get it wheeled in the shop and really get into it. Ill throw a charger on the battery and yank the plugs and belts and try spinning it by hand, and see where im at.

Are onan headgaskets hard to come by if i have to pull the head?

#11 DZG OFFLINE  

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Posted September 10, 2016 - 04:15 PM

Spins over free now.



I unhooked the deck belt, set the parking brake and spun it, then i hooked the belt back up, released the brake, and it still spun...wtf??




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