318 Rehab Help

Petebauer · Apr 19, 2019

Hi everyone - new here.

Long story and I need some help/guidance - bear with me :tango_face_wink:

After years of pestering, I recently received a 318 lawn tractor from my dad. The tractor has always been stored indoors and is in relatively good shape given its age. It originally had the B43G engine in it however dad removed that when he had issues and replaced it with a used P218G that’s in it now - this was done 8 years ago or. Apparently it started running rough and he didn’t want to deal with it (he couldn’t remember what issue it had) so he parked it and didn’t touch it for the last five years or so.

Fast forward to last week when I picked it up. Hauled it home and checked compression 120 psi on each side. Put fresh gas in and with relatively little effort I had it running. It had some surging issues and was burning some oil. I changed the oil with 15W45 and gave it a good seafoam treatment followed by new plugs. Now it starts, runs, idles great but it still smokes quite a bit. Most noticeably on start up and under heavy load however if parked in the sun you can see it’s smoking all the time.

I cleaned the air filter and popped the breather tube off which does not appear to be plugged.

My question for you guys is what’s next? Should I try running heavier oil and see how it goes? Or do I tear into it? (keeping in mind that while I am handy I’ve never tore down an engine past a carburetor cleaning).

Any help would be great.

Thanks,
Pete

Petebauer · Apr 19, 2019

Video of idle now. Cannot see smoke in the video.

https://youtu.be/RqsCiMJ0yGg

Junky · Apr 19, 2019

Well Pete, that smokin may be annoying but then if you live near a swamp it would be good mosquito control. As long as its running fine you can wait to overhaul it but just keep an eye on the oil level. With good compression numbers like that I would guess valve guides are worn.

mrbeef · Apr 19, 2019

How many hours Have you run it under load?

With it sitting 5 years I would recommend throwing the deck on and working it for a few hours and see what that does for the smoking. I've noticed my 318 when it sits for an extended period of time will smoke for a good 30 mins when it comes out of storage. If I use it frequently there is not smoking (maybe a faint puff on start up). I rebuild the engine about 5 years ago and it has maybe 20 hrs on it. (It's a play machine for me)

Country1966? · Apr 19, 2019

Junky said:
Well Pete, that smokin may be annoying but then if you live near a swamp it would be good mosquito control. As long as its running fine you can wait to overhaul it but just keep an eye on the oil level. With good compression numbers like that I would guess valve guides are worn.

I agree with Junky. Mow with it keep an eye on the oil though. if it isn't burning a bunch of oil I would not tear it down.

I seem to remember my 318 smoked a lot too.

Petebauer · Apr 19, 2019

Thanks for the advice. I was thinking about maybe going to a thicker oil as the oil I drained out was def thicker. I just want to be mindful not to get too thick and hurt anything.

mrbeef said:
How many hours Have you run it under load?

Hours are unknown. Dad cannot remember how many were on that P218 when he bought it - I just know it was a used engine.

No real load other than driving up a decent sized hill. I haven't put the mower deck back on yet to try that but certainly could.

rwmeyer · Apr 19, 2019

Pete, Be careful with a heavier oil, you may run into overheating problems. I'd go to a straight SAE 30 and see what happens. If your engine has an oil filter, use a detergent oil. If no filter, use non-detergent oil. Bob

KHodges · Apr 19, 2019

I'd also be cautious about too heavy an oil; stay with what is recommended for the engine under your operating conditions. The smoking is likely due to valve guide wear (especially if it lessens after it's run a few minutes), if not the oil scavenging ring. As long as you don't hear knocking that can be attributed to bearing wear, just keep the oil topped up and use it, since the compression is equal and not all that below new specs.

My '84 318 smokes, sometimes more, sometimes less, but it runs strong and mows great. I've just gotten into the habit of checking the oil every time before I start it, but that's not a bad idea for any machine of any age. I also change it more frequently than the book calls for. Mine had a partial restoration/rebuild (B43 engine), with new rings after a cylinder hone, but no valve work.

PA318Guy · Apr 19, 2019

Well if it sat for 5 years or so, the oil rings may be just "set" and might release with some running. I'd keep straight 30 weight in it and then add a little seafoam to the gas for the next several tanks and see if that doesn't help.

Petebauer · Apr 22, 2019

Quick update.

I changed the oil out for SAE 30 and ran it for a few hours this weekend. No better, maybe slightly worse actually.

Debating what to do next. I'm assuming I have to take the heads off to check and replace the valve guides?

KHodges · Apr 23, 2019

Petebauer said:
I'm assuming I have to take the heads off to check and replace the valve guides?

Yep. Since it's a side valve engine, you have to take the side covers off to get to the valve springs, but to remove the valves and the guides, you have to take the heads off as well.

Unless it's chokingly thick smoke, I'd use it as-is for a while; see how fast the oil level drops before you determine to rebuild the engine. If I were going to do a valve job, I think I'd also do a cylinder hone and new rings (spec the cylinder bore to see if it needs an overbore and new pistons), but if within specs, just hone and new rings. Generally, unless the engine gets oil starved, the bearings will last a long time.

Mine smokes bad enough that you can see it while the tractor is sitting still, but disappears while moving. I can mow a couple of acres before the oil level drops halfway on the dipstick marks (that's half a pint). I can live with that for quite a while, the 318 is my backup mower anyway.

318 Rehab Help

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