john deere b

[Jerrymouse41]

Hi i am wondering how to tell if piston rings are bad. the ones on the pistons now are sharp on all edges feel like they r new. Also wondering a little about the push rods, valve stems and springs, how to tell if they need replacement as well.the connecting rods both seem to be pretty dinged up along with the piston pins. Im planning on replacing both connecting rods and piston pins. Is there anything else i should be paying attention to while im at this stage of the repairs. thanks for any input. already i find this site a big help.

 

[kseaton65]

jerry was there a large ridge at the top of the cylinders, if so the engine has some wear, may need just a hone and re-ring if your in there at least, probably dont need to replace connecting rods, unless there bent, are they babbited or insert bearing type, i would say you would be wise to measure and make sure the cylinders are round, also it is a good idea to get the head inspected, known to crack and the valve seats to wear, if the valves can be ground that is good, i dont beleve you would need to replace the springs the engine doesnt really spin that fast and i dont think they really get too bad, really you have to look at what you are going to do with this tractor, parade it or work it, i am in the process of rebuilding a 49 john deere and have had to rebabbit the rods and mains, replace piston pin bushings, bore block 90 over and new pistons, as well as get a remain head do to a crack (cheaper to buy a remain than get the local machine shop to weld it for me) and new valve, engine should be it top shape when im done though

 

[Jerrymouse41]

kseaton65, there was not a large ridge, i was amazed at how easily the pistons slide out after removing the steering pedistal you suggested. As far as the connecting rods i am not sure the difference between the babbitt or the insert type bearing? Any info how to tell i'd appreciate. I plan on putting the tractor to work around here for now restore later. as far as measuring the cylinder i can use calipers to do this? The tractor doesnt look bad. i dont see any major wear on cylinders just on the inside of theconnecting rod and cap. The cap on both rods had a little brass shim that was on the bolts. The tractor is a 1952 B. Sounds like you are having fun with yours. This is the first for me i saw a good old tractor that was in the need for some attention and picked it up out of the blue. I wasnt expecting to buy a non running tractor but i did. so far is going well just cant wait to start it up for first time.

 

[Kurt_JDB]

Sound like you have babbited bearings. The shims are used to adjust the bearings as they wear. Unless the bearing material is coming apart, or the crank is bad, you can very possibly reuse your rods and bearings.

It is very important to keep up with the shims, and where they go. John Deere also sells an excellent shop manual for that tractor. This manual is well illustrated and will help you out a lot. A place like Deerly departed will sell you a copy for about half the price of Deere.

 

[Jerrymouse41]

ok i have a IT manual for the tractor, so the gouges and pitting is ok so i can reuse the one connecting rod? The shims are on the bolts that connect the rod with the cap, so this is what they call babbitted? when i bought the tractor it was missing one of the caps to the connecting rod and i figured that i could buy a whole new c rod and then move on.

 

[Paul Gasser.]

Good Question.

 

[Paul from MI]

You need to check a few things. First mike the crank. Rod journals a for the old babbit shimmed rods can be out of round quite a bit(maybe up to .005") if they are smooth. Remove shims to get the correct clearance.
Use a telescope gage or inside mike to check the cylinder for out of round and taper. You can probably get away with about .005-7" taper with a good set of rings. You can check for ring wear by putting the old rings in the cylinders at the tightest spot(usually at the bottom of the stroke). The end gap will tell you how much wear they have, it should be reasonably close to new specs. Considering the low cost of a set of rings, unless they're in really good shape replacement is in order. Next check the piston skirts for wear. If the cylinders are ok, you may be able to knurl the pistons to make up for some wear on the skirts. Don't forget to check the piston ring grooves for wear. If they are worn oversize it's kind of hard on the new rings so you may need to have them re-grooved & use some ring spacers to get the correct fit. Just some things to check before you have a lot of expensive machine work done to a good usable block & pistons.
Paul