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Discussion Starter #1
Hi all,

New to the forum, I have a 1993 318 with has been used in the northeast year round mowing grass, blowing snow and moving mountains of firewood. It operates anywhere from 90 to -20 degrees. The Onan motor has started banging very loudly like a bad bearing or some else which sounds serious. The oil and filter is changed religiously every spring, as well a tune up as needed. The local repair shop did not advise putting any more time or money into the motor. The engine has around 1400 hours. What engine life should I expect from the onan? 1400 hours seems to soon for major engine issues. What is your experience?

Dano
 

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Have you being doing the de-carbon of heads/valves every 200+ hours? (Depends on fuel with or without ethanol). Without a tear down of heads and oil pan removal for a formal inspection, it is all guess work. You have something wrong and it needs attention. I was able to rebuild mine for $1800 (parts & labor) with my supervision. That is with everything check at a local machine shop and re-bore of 0.020 over due to egging of the cylinder, happens on horizontal piston engines versus vertical. Otherwise it is a re-power and finding either a complete kit (wiring, PTO, drive shaft, mounts, exhaust mods, etc). Again if you can do the work, you save money. Or buy a new tractor.:gizmo::gizmo::gizmo:
 

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Hiya,

Did you check the driveshaft to the hydrostat pump? You have been pulling the screen and greasing those U-joints every 50 hours of service correct?

1400 hours on an Onan is getting up there when you would be thinking about a teardown to inspect and freshen things up. They tend to be a bit smoky and have that "Onan smell" around that time from the loss of oil control by the rings and guides. Parts for the B or P series are still fairly easy to get although they are going up in price as time goes on. The B&S or Honda conversions are quite popular and a great alternative for the DIY. (I prefer the B&S) There are places that sell complete conversion kits that make it a simple bolt on. I would stay away from the Harbor Freight Predator engines, they might be good enough but I suspect they aren't the same quality of the Honda or Daihatsu (B&S Vanguard twins) engines.

If the 318 platform still meets your needs, I would re-power it as to replace it your looking at an X720 which is around the 10K mark, 2K for a rebuild or re-power is a much better deal.

Couple links to re-power places:

John Deere 318 - John Deere 318 Lawn Tractor

John Deere 318 Repower

https://repowerspecialists.com/collections/john-deere/products/johndeere318honda?variant=1861357273111
 

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Discussion Starter #4
Have you being doing the de-carbon of heads/valves every 200+ hours? (Depends on fuel with or without ethanol). Without a tear down of heads and oil pan removal for a formal inspection, it is all guess work. You have something wrong and it needs attention. I was able to rebuild mine for $1800 (parts & labor) with my supervision. That is with everything check at a local machine shop and re-bore of 0.020 over due to egging of the cylinder, happens on horizontal piston engines versus vertical. Otherwise it is a re-power and finding either a complete kit (wiring, PTO, drive shaft, mounts, exhaust mods, etc). Again if you can do the work, you save money. Or buy a new tractor.:gizmo::gizmo::gizmo:
Thank you bloodrunsgreen, this motor has never been de-carboned, shame on me. An engine rebuild is over my head, so that option is out. How many hours on the motor before you did a rebuild? I would like to gauge if my motor died prematurely or if 1400 hours about the average life cycle.

Dano
 

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Discussion Starter #5
Hiya,

Did you check the driveshaft to the hydrostat pump? You have been pulling the screen and greasing those U-joints every 50 hours of service correct?

1400 hours on an Onan is getting up there when you would be thinking about a teardown to inspect and freshen things up. They tend to be a bit smoky and have that "Onan smell" around that time from the loss of oil control by the rings and guides. Parts for the G or P series are still fairly easy to get although they are going up in price as time goes on. The B&S or Honda conversions are quite popular and a great alternative for the DIY. (I prefer the B&S) There are places that sell complete conversion kits that make it a simple bolt on. I would stay away from the Harbor Freight Predator engines, they might be good enough but I suspect they aren't the same quality of the Honda or Daihatsu (B&S Vanguard twins) engines.

If the 318 platform still meets your needs, I would re-power it as to replace it your looking at an X720 which is around the 10K mark, 2K for a rebuild or re-power is a much better deal.
Thanks tomd999,
I do pull the screen every spring and grease the u joints. I have been looking at new JD X series and the price has me thinking of repowering. Honestly, the 318 still meets my needs, even though the thought of a new tractor is appealing. I will look into the B&S or Honda conversion more closely.
Dano
 

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Thank you bloodrunsgreen, this motor has never been de-carboned, shame on me. An engine rebuild is over my head, so that option is out. How many hours on the motor before you did a rebuild? I would like to gauge if my motor died prematurely or if 1400 hours about the average life cycle.

Dano
Had close to 3000 hours on the engine, that is why it had to be bored. Everything else was well within tolerances. Mine was using a ton of oil/hour, and noticed a loss of power and rough running. So yours may be just banging on the build-up of carbon. Also check the oil pan for sludge buildup (oil flow restriction).

If you go with a repower, make sure that the engine has a 12VDC output rated at 20 Amps for driving the electrical load (PTO, charging battery, lights, aux gears) just like the Onan, otherwise you will run into issues later.
 

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Dano, As appealing as a new tractor may sound, you're NOT going to get the 25 years out of a new tractor that you got out of your 318...I'd say more like 5 years MAX!

As far as rebuilding being "over your head", lot's of people here will help and an Onan Service Manual will walk you through the process. The precision stuff, like measuring & machining can be done by local shops...unless you have access to the equipment. It's just a pile of metal, nuts and bolts. Don't be afraid of it and it'll be a GREAT learning experience for ya. Bob
 

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I had the Onans in my 318 and 420 rebuilt. The 318 was using oil, and the 420 had a broken ring, which kept it from starting. Didn't regret doiing a rebuild in either one. Unfortunately, with the 420, I broke one of the mounting bosses for the starter, and didn't know how to repair it. I repowered with a Honda from Small Engine Warehouse. I later discovered how to repair the starter mount, and sold it to a friend to put it into his 318. Still running strongh today. I since picked up a donor 420 with an Onan that uses oil. I am very much tempted to rebuild it. I was told that the cause of oil consumption was that the end gap on the oil rings opens up with time.

I wouldn't be afraid of finding a good engine shop and haviing them do a rebuild. Pulling the motor is not very difficult. If you do pull the motor, I would recommend changing the u-joints on the driveshaft while you have it out.

As was pointed out, the new X series are very nice, but you won't get 25 years out of it like you have the 318.
Dave
 

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It sounds to me your engine has a rod bearing knock. The Onan is definitely a good engine to rebuild. I was lucky to have had a family owned small business that specialized in rebuilding Onans. Mine was done 5 years ago. Cost me 1,500 dollars. Nice thing about a rebuild is a P218 ends up being a 20 horse instead of 18!

My tractor is a 1987 316. Not much difference from a 318.
 

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Just FYI, but they quit making the 318 in 1992, so if you go looking for parts by year, you will run into issues if you say its a 1993.

1400 is probably about right, considering the lack of decarboning.
Really, thats the big issue with the Onan, along with the over rev due to the internal governor flyball retainer slipping.
In generator service they last an exceptionally long time. Trouble is, generators seem to get a whole lot better service than tractors do.

My 318 was repowered with a P220 at 1250 hours due to the governor issue. At that time I was looking at all the repower kits available.
Back then, the Kohler was the best option. Trouble now is that the company that had the best kits isnt around anymore.
I would still pay more for a Kohler vs the others, but if that wasnt an option, Id certainly take the Vanguard over the Honda. The Kohler over Vanguard is just personal preference. The Honda wouldnt go in my tractor simply due to all the issues they had originally, along with a few other minor things.
When the Honda kits first started popping up, there were quite a few issues with them, from alignment to cooling, requiring the side panels to be left off, which is a poor "fix" to say the least.
Jimsrepair seems to have the best Vanguard kits, or at least hes been around the longest, and has sold quite a few of the kits.

I prefer the Onans torque, even though it uses more fuel, and its sound. Nothing barks like an Onan under a heavy load.

In your case, check the compression, make sure your driveshaft isnt loose on either end or the U-joints arent worn, then go from there.
Its possible you could just replace a few parts and be back in business. Its also possible you could have a hefty rebuild tab too, in which case a re-power would be a cheaper option.
 

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Discussion Starter #11
Had close to 3000 hours on the engine, that is why it had to be bored. Everything else was well within tolerances. Mine was using a ton of oil/hour, and noticed a loss of power and rough running. So yours may be just banging on the build-up of carbon. Also check the oil pan for sludge buildup (oil flow restriction).

If you go with a repower, make sure that the engine has a 12VDC output rated at 20 Amps for driving the electrical load (PTO, charging battery, lights, aux gears) just like the Onan, otherwise you will run into issues later.

Thanks, I would have guessed upwards for 2000 to 3000 hours for the Onan motor. I am looking into re-power and also asking around for a shop to be-build. Who knows, may try it myself.
Dano
 

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thank you

Thank you all for the good advice and sharing your thoughts on the 318 Onan engine. I moved to West Chester, Ohio a couple of years ago and do not have a network of friends or support like I once had in Vermont. If anyone knows of a shop willing to work on this motor in southern Ohio, I would be very appreciative.
I reality, I would much prefer to keep the old 318 over the newer models.
Dano
 

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Hiya,

The only tractor guy I know in Ohio is Jan Peterson at Shearer Deere. Not sure where you are in relation to their locations but if your not too far, give Jan a call, maybe he can help you out or find you a good place. He was very open and honest with me several years ago when I was looking at some used equipment.

Tom
 

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Dano, this is who did my P218. They are good with Onans. They are in Minerva OH.

https://shop.kustomlawnandgarden.com/contactus.sc

They will send you a shipping carton to put your engine in. They paid to ship both ways! I'm not certain things are done the same, but I would call them and get some info.
 

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Update on my 318

Long story short, I am happy to report this weekend by shear accident, I found a shop that specializes in older JD motor rebuilds in central Ohio. The 318 will be picked up this week for the engine re-build. Keep you posted on the results.
Dano
 
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