I need to rebuild the engine on the '39 H my grandfather purchased new. One of the cylinders has no compression and thought this would be a good project with my 2 boys. Where can I find info on what is required to do this? Do I need to split the tractor in half? Where do I buy the parts. Is there a site dedicated to this subject? Thanks
No compression could be something as simple as a stuck valve. How's the other cylinders' compression? and how's the exhaust manifold look inside? full of tar or clean? There are a few sites much more focused on old tractors than this site. It should be a piece of cake to come up with the answers you need. You shouldn't have any trouble buying new engine parts, just a little time looking and waiting for delivery.
The engine was rebuild in the early 70s and very little time was put on it. When I took it out in the mid 80's for a few tractor pulls (running on the good cylinder) the cylinder had no compression and I didn't have enough engine experience to address at the time. In retrospect, I should have checked the simple stuff. I do plan on doing a leak down test prior to opening it up. I stopped running when I found 2 1/8" to 1/4" ball bearings in the oil the last time it was drained. As this was before the internet, I had no easy way of identifying where these could have come from. I realized this may not be the best site for this tractor; however it is great for my Case580.
A stuck valve is sounding like a better guess. That's the only way I know of that an engine can lose compression from being stored, unless it was full of water and froze. Possibly even more likely in a rebuilt engine that's not broken in. I don't know the poppin Johnys, but there should be a valve cover to check the valve operation. If one of them isn't operating then it's fairly simple to get them loose, it's only the spring that closes them, and they weren't too worried about somebody floating the valves... According to googley, the H has ball bearings for the cam (and an eccentric cam bearing mount that adjusts the gear lash!) so that's my guess where the balls came from. Some Farmall's had ball bearing on the crank, but I don't think Deere's did that. In either case you probably don't want to run it if there's a ball bearing coming apart. I think there's a crankcase cover on top that lets you access and maybe see what's loose. Also, the leakdown test on a horizontal cylinder might not work to add oil to check the rings.
A better place to search might be www.ytmag.com in the John Deere section. Lots of info and experience there.
Here's another resource you can check... http://www.tractorbynet.com/forums/john-deere-vintage-tractors/ Some good folks over there...
To buy the parts I'd go through your local Deere dealer. But I'd go with the aftermarket parts offered through Deere. Also, maybe sunscribe to http://greenmagazine.com/ or http://www.two-cylinder.com/ which has tons of information and parts resouces. I'd take the valve cover off and go from there like mentioned. You do not have to split the tractor to do an overhaul. The crank case cover is the plate with bolts on it right in front of the gear selector/transmision cover and steering column. Two cylinders are fairly simple and can be fun projects!
Thanks for the all the helpful info and links! I think I will go out with the boys (9&12): 1: Put low pressure compressed air into the bad cylinder and find out if it leaks through the intake, exhaust, or crankcase at TDC. 2: Pull valve cover if leaks out valves and inspect. 3: Pull crankcase cover and governor, inspect to find out where the balls came from. If all goes well, put it back in the annual tractor pull.....