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Spencyg

Engine Rebuild Time....bummer!

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Spencyg
Well fellas...the little tractor that could...can't. I knew I was in trouble this winter when I topped off the engine maybe a bit too high and had really bad blow-by with oil smoke spewing out of the muffler. Since then the crankcase can't be filled past 1/2 of full capacity without it blowing past the rings, and when its loaded down it also smokes blue. I was considering tearing my entire tractor down this spring to sandblast the metal and repaint, and now it looks like I'll also be overhauling the engine as well. Should I just do the rings with a light cylinder hone, or an oversize piston set? I don't know what the ring wear on the cylinder walls is yet, but what amount of wear dictates an overbore(measured by piston ring gap difference)? I also think I should update the gaskets at least, and possibly the valve springs. Anything else I should do while I'm in there? I don't to spend a ton of money onf this engine...its hard enough keeping myself from buying a 20hp V-twin instead of rebuilding, and economy is the swing vote. By the way...the engine is a Briggs 326431, 16hp horizontal single cylinder. Thanks Spence

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JP
Hi Spence, Ahh... The old "Starve a cold or Feed a fever" (or is it Feed a cold & starve a fever??) LOL. In this case, 'Should I just put in rings' or piston/bore & rings (valves figure in there too!). I usually mic everything up to see where I'm at compared to specifications. If the piston tolerence is more than %50 out & if there's any scoring/damage to the cylinder - piston & bore. If not, check the ring end gap with a new set of rings & compare that to spec. There's not any more shortblocks available for those Briggs. I opted to just do the shortblock a few years back, it WAS cheaper. Switching to a newer engine will pose a few challenges in terms of adapting the 'new' to the old setup (PTO's & drive & electrical systems) and the biggie, not cheap! Keep us posted on what you're going to do. There's enough knowledgeable people aroud here to keep ya on track! Take Care, JP

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Spencyg
I pulled the head last night, finding raw oil all over the top of the piston and the combustion chamber. It is definately time for some fixin'. There is only a thousanths of an inch or so of ring wear in the cylinder wall, so I'm going to hone the bore and throw in a new set of std. bore rings. I also have a gasket set coming, along with valve springs and a few other things. My big problem at this point is getting the old exhaust off. I'm going to fabricate new exhaust once I put the rebuilt tractor back together, so salvaging what I've got isn't the issue...its the rust that has welded the outlet pipe to the cylinder that is the problem. Doh! I'll figure it out eventually... Spence

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PatRarick
Did the problem start suddenly? If so, I would check the breather. If it is plugged, it will cause enough crankcase pressure to push the oil up past the rings. If the valve inside the breather is broken or stuck open, it will suck oil through the carb and into the cylinder. Pat

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Spencyg
Yes it was quite suddenly that this stuff started happenning. I've almost got down to the breather with the teardown, so I'll know for sure. The engine has never been rebuilt, and since its 25 years old than I'd say its time anyway. Oh and by the way...after liberal amounts of penetrating lube, I was able to completely disassemble the exhaust without any damage...so yes...loosening the muffler bearing was the key to the whole thing :) Spence

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Spencyg
I pulled a good portion of the engine apart last night (as much as I'm intending to pull at least) and discovered that the top compression ring had broken in 3 places. This being the case, the cylinder bore is scored where a small piece of the broke ring (~1.25") had been resting. I think the depth of the scores are around 0.005". The piston is also messed up on the side that was closest to the valves...looks like it was worn away probably 0.020" between the top of the piston and the 2nd ring landing. The rod seems fine, as well as the wrist pin. With so much distruction in the upper end, but also so little "tractor money" available (followed by a need for the tractor in a couple weeks), I've decided to just clean up the piston as much as I can, agressively hone the bore, throw in new rings, and reassemble. I can't justify spending money on an engine that is already outdated and worn out. I'll plan on rebuilding the tractor this fall with a 20hp V-twin and hydraulics. Son of a Gun. Spence

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PatRarick
Just a suggestion, but I would have the block rebored and install an oversize piston. Rings are going to cost you about $25. The oversize piston with rings will be about $100, and the rebore about $30, so you will have an additional expense of about $105 by going this route. This engine has already lasted about 25 years, and with a rebore you should get another 25 years out of it. The V-twin is nice and does make a fine upgrade, but it is hard to match the torque of the 16 horse cast iron that you now have. I have a few V-twin conversions in my stable, all upgrading in power from the original engines. My experience has been that I see a power increase when pulling, but a slight decrease in the operation of all PTO powered equipment with the exception of the roto-tiller. You will easily bypass the $105 additional expense of a rebore by converting to the V-twin. Pat

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Spencyg
Pat, you are right. I have changed my order to a +0.020" piston/rings, and a gasket set. The machine shop will doa .020" overbore for $40. I'll be spending double what I originally thought I would, but the engine will also last many more years. The original piston is so trashed that my new rings would probably break the first time I ran it. Of course, it has been running pretty well for quite some time, and from the looks of it, this havn't been in one piece for quite awhile. So who knows...I'll at least have the peace of mind that it was done right...and I cna get back to other more important matters...3 point hitch:) Spence

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