Test of Rebuilt Onan B43G 18HP on Homebuilt Stand

A slideshow of pics followed by the first two tests of the flat 2 cylinder Onan engine my dad rebuilt this summer. The engine is from a John Deere 318 garden tractor.



25 thoughts on “Test of Rebuilt Onan B43G 18HP on Homebuilt Stand

  1. Hi, Great job!

    I am looking for a straight crankshaft for a P218g Performer. It was a tapered crankshaft. Is it possible to change it to a straight shaft crank?

    Do you know where I might find one?
    Also looking for the rear plate and bearing with shims for end play adjustment.

    I got the Onan off a welder at the scrap yard and some how the person who owned it before broke the shaft OFF at the rear plate and that also was broken during the incident!



  2. A good source for Onan parts is Onanpartsdotcom. They have mostly new, and some used parts available. Tulsaenginewarehousedotcom has Onan crank diagrams on their web site. Ebay is another good source for Onan parts.
    Many can be found under John Deere 318 since thousands of these tractors were built with Onans. Other Ebay searches such as Onan parts, Onan P218, etc. also produce good results. Good luck with your project, these are fine engines that when properly rebuilt will last for years.

  3. Have an 18 horse Vanguard in my 314, my Dads 317 has the original 17 horse Kohler both twin cylinders and good engines. However, you can't beat the sound of an Onan 18 horse. Sweet.

  4. Running very smooth I just uploaded a video of the 20 hp Onan we put on a Case 446 Lawn tractor. Could you tell me from looking at the ignition plug on my video which wires on the plug in are the ignition switch wire?

  5. @jenniferheisecarver Thank you for your information. I also wondered is the cut off diode necessary to run it with just a key switch. I think that part is still on the craftsman. we may have to find it.

  6. @4dairyairs
    I have a question for the Onan expert here. I have 16hp, 18hp and 20hp engines. All pistons come up to the deck, or just below except the 18hp. They come out of the block about the thickness of the gasket. Bore is standard, everything is original as I can see. Is this normal for the 18's?
    Thank you for your time.

  7. Nice job. My uncle's 318 had the B43G engine in it until about 10 years ago, when my cousin and I overheated it and it almost blew up. He dropped a replacement Linamar LX770 engine in it and the tractor runs much stronger and hasn't given him any problems.

  8. I just spoke with an old man I have known for a while. He owned a small engine repair shop his entire life. I had one question for him. "What is your favorite small engine", he did not hesitate. 18hp Onan from a John Deere 318.

    I need one of these for a project, so if any one knows where I can get one I would appreciate it.

  9. Good question. I don't think it has run since these tests in 2009. My dad is currently building a new garage that will give him more room for his projects, such as restoring the body of the John Deere 318 that this engine is intended for.

  10. I have a P216G and I desperately need a muffler. I got the engine for free and it is practically new, been ran about three times. I just need a muffler for it and can't find one. Do you know where I can look?

  11. super engine…….just a piss poor design for the starter setup in it. it has a bad cheap starter, will bust the casting on the block over time…

  12. My John Deere 318 wont pump fuel at high rpm any ideas will pump at low idle fine Has a Briggs fuel pump will it work if I put another Briggs pump or should I just put a onan pump on It

  13. Where can i find a 2 port coil for this engine? 2 port meaning 2 spark plug wires coming out of it, plus the positive and negative posts (for the ignition) coming out of it….

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