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Discussion Starter · #1 ·
I have just replaced the pistons and rods in my Onan because one of the rods was broken into dozens of pieces when I bought the machine. I bought used parts offline and they were in perfect condition for what I was doing. There did not seem to be any damage to the crank other than some minor scoring and I put everything back together using proper tools, techniques, and assembly lube. The only issue that concerns me at this point is when I turned the engine by hand to make sure everything was right, it hangs just a bit at one point. It will turn, but just gets difficult. This is my first rebuild so I'm curious if this is something to worry about or if it will work itself out.
 

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I have just replaced the pistons and rods in my Onan because one of the rods was broken into dozens of pieces when I bought the machine. I bought used parts offline and they were in perfect condition for what I was doing. There did not seem to be any damage to the crank other than some minor scoring and I put everything back together using proper tools, techniques, and assembly lube. The only issue that concerns me at this point is when I turned the engine by hand to make sure everything was right, it hangs just a bit at one point. It will turn, but just gets difficult. This is my first rebuild so I'm curious if this is something to worry about or if it will work itself out.
Tell us about that crank journal with minor scoring and no damage, spin it over a few rounds by hand and then take that rod cap off and take a look at the surface area.
 

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Discussion Starter · #3 ·
the crank turned just fine on it's own. it wasn't until i got the new pistons in that there was any resistance for part of the turn. you can turn it all the way around by hand, just difficult at one point
 

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the crank turned just fine on it's own. it wasn't until i got the new pistons in that there was any resistance for part of the turn. you can turn it all the way around by hand, just difficult at one point
I am not jerking you around, I am an engine builder for 68 years of my 83 years, lack of lube is what pops the rods in an onan, never saw one popped with out some damage, you may not know what to look for, how much aluminum was there on the rod journal, some times the aluminum will smooth out and not be visible to an untrained eye, the journals must have a mirror finish all way around, start by taking the piston and rod back out of cyl. in question and try a test turn, if necessary take out the other one and try, Is cam and valve train complete, if not a complete take down, may be a chunk of rod up behind cam. engine building is not a fun and games, serious work, PS did it get the oil tube
 

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Discussion Starter · #5 ·
The oil tube was fine and i checked everything to make sure I got all the pieces of the rod out. The journal in question was fine except for a line scratched in it all the way around
 
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