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Discussion Starter · #1 ·
Hey folks
I've got a 318 that has burned some oil since I got it. No biggie, it's an older tractor.

Since spring it's gone from a quart per 4-5 hours (monitored and topped off per mowing, at about an hour each mowing) to the last time I mowed, I topped it off, mowed and rechecked it and it was down an entire quart in just that hour of run time.

Obviously something has headed for it's end of life and this motor isn't going to make it much longer. So it's time to take action before this thing blows up mid mowing or when the snow flies.

When the consumption started to increase, I tried to be pro-active and picked up a P220 that was a back up oil pump for the quenching area of a forging plant. It was only used when the power went out. They would run it up to operating temp monthly and change the oil every 6 months as PM. The gentleman I got it from said the hour meter where it was installed was under 250hours. (243 is his recollection)

Perfect for a new motor for my 318! Till I got it home and pulled the hydraulic pump off. It has the wrong crank. Damn, there goes my easy button.

OK, well I have a "spare" P218 motor that has the right crank, but had low compression. So I pulled that motor down this weekend to get the crank out to swap out. The crank looks good, but I need to make a puller to get the cam drive gear off. When I pulled it down the top ring on both cylinders was broken. That explains the low compression. Bores look pretty good, and the pistons look good. I could probably, hone, re-ring it, and it would be good to go. BUT... I haven't measured the bores. They could be egg shaped, and I wouldn't know yet.

My question..... I have a gasket set, but no rings. I didn't try, but I'm 90% sure that if I left the heads on the P218 I tore down there is NO way that I could have gotten the crank out of the parts motor.
That being the case, I'm going to have to pull the pistons on the P220.

Should I do it "right" and hone the cylinders, and install new rings.... or can I get away with a light deglaze/hone, clean the pistons and rings and reinstall the pistons/rings as is?


I'm not looking to spend a bunch of money on this thing. It's a good tractor, but I'm missing the accessories I want for it (FEL, larger deck, tiller, rear pto, 3pt) so I'm planning to buy a 1025R in about a year. (Thanks TTWT and GWT! lol) In an emergency I could probably pull the trigger on that purchase now, but I'd like to get a few of my financial things squared away first.
 

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Typically, if you hone and just throw rings at it, it will last a couple years.

Call Boomer he's a wealth of knowledge and sells stuff pretty cheap.
 
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I would pull engine, then pull the heads, inspect the pistons (are they original, or stamped with some numbers (previous bore job done), check valve for need of adjustment, or wear in the stems or guides, measure the cylinders in lots of places, look for egging of the cylinders. That will help to determine if a bore job is needed or it is past saving block. Boomer may have a short block available, besides all the pieces for a rebuild.

Or buy a re-power kit
 

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DDood, We can "suggest" for pages and pages, but until you open engine up and inspect sizes, we can't give you the correct answer! Follow Blood's idea and inspect, THEN post questions if unsure. Bob
 
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Discussion Starter · #6 ·
Basically I'm asking if I should for sure re-ring it or if I can reuse the existing rings in the low hour 20hp motor when I pull it apart. For the $50 I'll probably just order rings.

I NEED to swap the crank because the PTO end is different.
 

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If bores are not worn oversize or out of round...determined by measuring bores... and rings are not worn... determined my measuring end gap... everything will be fine with a quick honing. Without the actual sizes, I can't say what will be OK and what won't be OK.

If you don't have the skills or tools to do the measuring yourself, go to a local machine shop... probably for a cost... or a local high school/trade school with an auto shop or a machine shop... typically free! Bob
 

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Are you doing all the oil level checks with the engine cold?

"I topped it off, mowed and rechecked" suggests that maybe it is sometimes getting checked and topped off when hot/warm?

Have you changed the oil you are using?
 

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Discussion Starter · #9 ·
Are you doing all the oil level checks with the engine cold?

"I topped it off, mowed and rechecked" suggests that maybe it is sometimes getting checked and topped off when hot/warm?

Have you changed the oil you are using?
I typically check it before I start it each time. So in this case, I checked it STONE cold (sat for 3 days) and topped it off. I mowed, then went inside for an hour and rechecked it before I restarted it to give my son a ride in the wagon and found it another quart low.
 

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Discussion Starter · #10 ·
If bores are not worn oversize or out of round...determined by measuring bores... and rings are not worn... determined my measuring end gap... everything will be fine with a quick honing. Without the actual sizes, I can't say what will be OK and what won't be OK.

If you don't have the skills or tools to do the measuring yourself, go to a local machine shop... probably for a cost... or a local high school/trade school with an auto shop or a machine shop... typically free! Bob
Of course without measuring there is no real knowing. I do have the equipment and knowledge to Measure everything. (I have micrometers, including bore mics)

The reason I ask is, in higher speed/RPM applications they say if the ring comes out of the bore after it has been ran it is junk and needs to be replaced. I wasn't sure if anyone around here had reused rings on an Onan. Technically it is a low speed engine, but is air cooled, and may have higher cylinder temps causing the rings to be more tempered, which... would then cause issues.

After thinking about it the last few days, and seeing that rings are easy to obtain (2 years ago they were not when I looked for a different motor) and cheap, I'll just replace them and not worry about it.

But I do agree, without measuring the bores with the proper equipment, it really is impossible to tell. I would think that with the low hours this 20hp motor has, that everything should be good to go with a light hone and a set of rings.
 

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Opening it up and doing the measurements will also tell the truth on hours or hard use. Any oil leaks (breather into air box, crank seals (blower/PTO sides), oil pressure switch, oil filter mount, oil pan) that would also lead to oil loss?
 

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Discussion Starter · #12 ·
Opening it up and doing the measurements will also tell the truth on hours or hard use. Any oil leaks (breather into air box, crank seals (blower/PTO sides), oil pressure switch, oil filter mount, oil pan) that would also lead to oil loss?
The motor in the tractor needs to stay alive till I get the P220 running and ready to drop in.
Allegedly the P220 is low hours (under 250) if the crank was correct I'd drop it in place of the B43G and never look back. . Thankfully I have a "parts motor" (P218) that has the correct crank that I can pull the crankshaft out of, then swap the crank into the P220 and then I can drop it into the tractor. (Yes there is 3 different motors at play here... Motor in the tractor B43G, parts motor P218, and the replacement motor with the wrong crank P220)

After I discovered the lack of oil, I checked for leaks, and I didn't find any leaks. I suspect that it's worn and has a bunch of blow by causing it to consume oil that way, or possibly stuck oil control rings. Either way, the consumption has made a quick jump from a quart every 4ish hours to a quart every hour.
 

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Can't you swap the entire P220 engine into the 318? If I remember correctly, the P220 is the later engine for the 420, with 20 hp instead of 18hp. I have a 1984 318 which has a B48 engine, the early 420 motor, in it. I had to look at the engine plate to be sure, I thought mine had the original engine in it, but someone had swapped the larger displacement engine in at some point, and it looks to be a direct exchange. Only difference is bore and stroke.
 

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Discussion Starter · #14 ·
Can't you swap the entire P220 engine into the 318? If I remember correctly, the P220 is the later engine for the 420, with 20 hp instead of 18hp. I have a 1984 318 which has a B48 engine, the early 420 motor, in it. I had to look at the engine plate to be sure, I thought mine had the original engine in it, but someone had swapped the larger displacement engine in at some point, and it looks to be a direct exchange. Only difference is bore and stroke.
The 220 I have, as I noted, has the wrong crank on the PTO side. So this requires the crank to be changed.

The difference between a 218 and a 220 is the cam and carb.
 

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Hmm, OK, sounds like you know your way around engines and have the needed skills & equipment. I'm gonna take a different approach here!

By the time you get rings, pull engine, install rings, and reinstall engine, you're looking at prolly a week and $100 (??) for rings, gaskets, etc. That'll buy you a LOT of oil to keep existing B43 engine going for another week or 2. Start on crank swap NOW and you may have it ready to go in by this time next weekend! Bob
 

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Discussion Starter · #16 ·
Hmm, OK, sounds like you know your way around engines and have the needed skills & equipment. I'm gonna take a different approach here!

By the time you get rings, pull engine, install rings, and reinstall engine, you're looking at prolly a week and $100 (??) for rings, gaskets, etc. That'll buy you a LOT of oil to keep existing B43 engine going for another week or 2. Start on crank swap NOW and you may have it ready to go in by this time next weekend! Bob
That's my exact plan! My worry is that this B43 is going to give up the ghost before I get the cranks swapped over!
If that happens... I may be "forced" to stop at the dealer and pick up a 1025R...that's a future plan...so hopefully I can get this swapped over so I don't have to make that step earlier than planned.
 

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Stick with your plan! Your B43 may self destruct the next time your turn the key or 1000 hours later! Monitor oil level, warm for 2-5 minutes after starting, and hope for the best! Nothing else you can do. Bob
 

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Discussion Starter · #18 ·
Stick with your plan! Your B43 may self destruct the next time your turn the key or 1000 hours later! Monitor oil level, warm for 2-5 minutes after starting, and hope for the best! Nothing else you can do. Bob
I'm hoping that the B43 stays together, then I can rebuild it properly for a 317 I have that needs a motor.
 
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