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JD4L
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431 Posts
Discussion Starter #1
Hey folks, been a while since I posted. I noticed last year towards the end of the mowing season, my 318 puffs a bit of blue when I go to throttle up... Should I start looking into a rebuild or just wait it out and see where it goes? Also, I only have 750 hours according to the meter. Unless someone fiddled with it! Thanks!

Tonka
 

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JD4L
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431 Posts
Discussion Starter #2
Bump to rid of smoke signals! Where can I get a rebuild kit for this Onan? Just in case...
 

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Super Moderator
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13,363 Posts
Well the first thing I would do is check the compression. Do you have a P218 or B43G in your 318. How involved you get in your rebuild really depends on how the cylinders look and how far you want to take it plus skill level.

Minimum compression is 75, so if you are above that I would wait and just keep the oil changed. Below that and its time to crack it open and take a look-see.

As for hours, it might be correct, the tale tail sign will be any sludge in the oil pan. I pulled one engine apart that had 950 hours on it and there was still cross hatching on the walls. On the other hand, I pulled an engine apart that had 850 hours that was scored, and pretty much shot... the difference.... Oil changes and maintenance. The 850 hour engine was dirty and just in terrible condition. So if you take care of it, it will take care of you.

Tips for your rebuild, get the right piston rings. There are a couple of different styles. If you replace rods or pistons replace them in pairs or find a matching casting number.

As for rebuild kits, I would encourage a look at the engine and then determine what needs to be done, THEN buy the necessary parts. See below for parts sources.

Good Luck!

As a side note:

A couple of misconceptions about these Onan's:
1) Parts are expensive. They are no more expensive than OEM Kohler parts or the like, they are just in different places. Onanparts.com is a great resource along with Boomer_Influence a member here on MTF.
2) Rebuilds are expensive. Not really if an Onan has been taken care of you can rering the engine for less than $200. Now is you want a COMPLETE rebuild be prepared to let go of some Benjamins.... but steps that drastic are typically only for engines that have many thousands of hours on them.
 

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Premium Member
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373 Posts
There are a couple of things you might want to check as well. The heads have a tendency to build carbon deposits, and a leaky valve could cause puffs of smoke. The valves are also supposed to be adjusted every 200 hrs. There are carbon kits - with new gaskets etc available for about $70 - I'd suggest carbon removal and valve adjusting to start with. That will also be a good chance to inspect the internals.
 

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JD4L
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431 Posts
Discussion Starter #5
Sounds good guys! I got a carb rebuild from Boomer for an old Roper I had... I will check into it a little deeper! Thanks again!
 
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