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Discussion Starter #1
I got an 86 318 with 1634 hours on it. It smokes on start up and does slowly burn oil. Takes me about 2 hours to mow the lawn and I have to add oil every few times mowing. Tractor runs pretty good but do get a slight surging around 1/4 throttle but that's about it. I've had the carb partially apart and pulled the float, needle, and pilot jet out and soaked up all the gas in the bowl and cleaned it out the best I could. Dumped seafoam in the bowl and let it sit a bit and put it back together and started it up and smoked pretty white till it burned the seafoam out lol. I do run it in the gas sometimes too to help clean the carb. I tried spraying carb cleaner around the intake gasket to check for leaks but engine rpm didn't seem to change so I'm assuming that's ok. Anyways, I guess what I'm wondering is do I re-ring it or new rings and pistons or just keep running it the way it is and if it craps out , repower it? I'd rather not spend over a grand on a full rebuild kit. Thanks in advance for any help.
 

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have you removed the engine tins and cleaned the cooling fins? if it gets too hot oil will burn

at your hours it might need to be bored out for larger piston and rings but you wont know until you remove the heads and mic it out

my onan has over 2000 hours and burns oil and if I rebuild it some day it will be with new rods, pistons and bored out.
 

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Discussion Starter #3
I had the motor out and cleaned under the tins like a year and a half ago. Lots of crud in there.
 

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I had a 318 that I did a ring job due to oil usage. Pulled the pistons and measured everything up. Found out that everything was ok with the exception of the ring gaps which
were out of tolerance. Excessive ring wear. Ordered a ring set, honed the cylinders to get a good cross hatch, put it back together and the oil usage stopped. Sold the tractor and from what I have heard still runs beautifully and doesn't use any oil. It had approximately 1000 hrs on it and likely got dusted due to poor maintenance and infrequent air filter changes from the previous owner.
 

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Discussion Starter #5
I could pull the heads and try to get the measurements of the cylinders. Check for scoring or anything and then also decarbon the heads.
 

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I had a similar problem, burned 8oz. of oil every mowing of 2 acres. New oil was became black, full of carbon soot and thick after one mowing. But the B43g engine ran great and had plenty of power. My neighbor who owns a repair shop told me it sounds like worn oil rings and to open it up, and if all looks ok inside just do a ring job. Spent $22 for each ring set and $9 for an oil pan gasket. Bought 0.010" over rings and ground the end gap to spec. The new oil rings are a 3 piece. Each wiper moves independently and I feel they are superior to the originals. I have two mowing seasons and one plowing, about 200 hrs. on it and all is good.
 

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I had really high compression and oil use. Did basically what Mike and Andrew did; pulled it out, opened it up and measured everything. Replaced rings, valve springs and one valve. Was done in two couple hour sessions and for under $200. Runs great, no excessive oil use and compression is back to normal after decarboning the heads.
 

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I had a similar problem, burned 8oz. of oil every mowing of 2 acres. New oil was became black, full of carbon soot and thick after one mowing. But the B43g engine ran great and had plenty of power. My neighbor who owns a repair shop told me it sounds like worn oil rings and to open it up, and if all looks ok inside just do a ring job. Spent $22 for each ring set and $9 for an oil pan gasket. Bought 0.010" over rings and ground the end gap to spec. The new oil rings are a 3 piece. Each wiper moves independently and I feel they are superior to the originals. I have two mowing seasons and one plowing, about 200 hrs. on it and all is good.
No valve job or valve guides? No other gaskets needed? Got by pretty cheap and looks to be fixed.
 

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Discussion Starter #10
whats the diameter of the cylinders? The upstairs neighbor builds race car engines so I'm sure he'll have a mic to check it for me
 

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No valve job or valve guides? No other gaskets needed? Got by pretty cheap and looks to be fixed.
The compression was about 100psi. each side and visually the valve contact to seat looked good. My plan was to take a chance by doing rings and see what happens. Originally thought maybe a stuck oil ring. I even reused the head gaskets since they were on and off several times for decarboning. I know I will need a complete valve job eventually and even thought about buying all the parts now before they are unavailable. I see no reason to open it up again at this point since it is running so good. But I know that time will eventually come.
 
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