Hi everyone
I bought another OC-3 back in November. The tractor had been sitting at least a year, the motor was stuck. I pulled the head and put the mystery oil to it, in about 2 weeks, I put a pipe wrench on the hydraulic shaft , gave it a yank and it broke free. I let is sit in the garage until warm weather came. I got serious about starting it 2 weeks ago, with no luck. I did a leak-down test on it and had air escaping in all the wrong places. I decided that a tear-down was next. The oil rings on the piston were rusted closed and the valves apeared to have rust on the seats.I measured the cylinder walls and got .014 taper from top to bottom. Now here is the question. How much is too much taper, I really dont want to rebuild another motor so soon after doing the one for my farthers tractor. I have used citric acid to clean the rust off the piston rings and can lapp the valves in. Does it make any sence to clean everything up and get a year or so out of it?
Someone else should know about the taper allowance in the cylinders, however I would definitely not use used rings. At least hone the cylinders to clean them up and install new rings. They are pretty cheap.
As far as the valves, I would find a shop that you can take the block to (even if it's still in the tractor on a trailer) and have the seats ground and have the valves refaced. if the valves have rust pits, you'll spend days cleaning them up and they won't seat good. I don't think it will cost much to get them refaced and the seats lightly ground as long as they don't need the seats replaced.
Blake
Blake
I do not have a way to transport the tractor so if I wanted to have a machine shop do the valves I would have to pull the motor anyway. If I go to that point I probably should bite the bullet and bore it out. I was unsure how to get the lapping compound out of the motor if I did it myself, so it really makes sense to let a machine shop do it the right way. I do have a spare motor with .02 oversize pistons in it that I could use, that one will have to go up to the next size anyway. Another question "is the bell-housing the same on the OC-3 and HG"? When I was crawling around under the tractor that I bought I noticed that the bell-housing and the guide supports have been brazed back together. It looks like it must have fallen off a truck or something, this would explain why the fly wheel is off by 180 degrees. I have a spare bell-housing that I believe was from an HG, it looks exactly like the one that is on it. I also have a pair of spare guide supports that I can put on it. Will it be worth all the trouble to replace the guide supports, I assume that it is a big job? If I pull the motor I will replace the bell-housing.
As far as the valve grinding compound, I use the water based stuff and just wipe it off with a damp paper towel. Then, when you are all done, put a film of oil on them so they don't rust right away.
I would take the engine out and make a good inspection. If you have 014 taper and 20 over pistons it will be close if the cylinder clean up at 20. Out of round is a worse condition that taper. How much out of round do you have. Me I would have valve seats put in the block and maybe even save the money and get new valves as more years go by parts will become more expense yet. I would not lap them.
Well I have the motor all but out. The only 4 bolts that i have left to remove are the ones that lie under the guide supports. I was surprised when I found out that i needed to take the supports off to remove the motor. Will probably have it out this week, and into the machine shop to have it bored.
John
While I have the motor out I will plan on doing the valves right , grinding and new seats and will probably price new valves.
I think somewhere along the line someone mentioned what valves will interchange with the IXB valves. It may be a lot cheaper to use different valves that fit, rather than trying to find the exact replacement ones.