I gave quite a lengthy background in ep1 so now I’ll get into the meat of the restoration. I will try to keep this short and focus on the relevant technical aspects so you can learn from my mistakes without wading through verbiage. I have tons of pictures, and will insert the important ones, with the lesser pictures as links only. So don’t forget to click the links!
Disassembling an engine (or other item to be restored) is the number one place to make or break (literally) your rebuild. A few points to remember are:
- Study first - Look closely at each part before you try to pull it off. Sometimes things are not as they seem.
- Mark everything - Score, punch, twisty-tie, tape, bag… location AND position (up/down, left/right, front/back).
- Patience and lots of blaster will free up just about anything
- Use the correct tool for the job! Pliers and vise-grips should not be used on bolts
- Don’t throw anything away till you finish the job.
On to my engine!
The first thing I did was pull the crank cover. From the picture you can see that there is a little bit of rust, but overall just lots of oil residue and some dirt. Not bad for starters. With the crank exposed I punch marked the rod, rod cap, and both mains. I also marked the cam gear and magneto gear, but I managed to forget to mark the crank gear! I will have to set the timing when the engine is together.
Next I pulled the governor and cam side cover plate (Picture) and replaced the screws back into the holes. Putting screws back into their hole is one of the easiest ways to keep from loosing them, as long as they won’t get in the way later on. You can see that there is quite a bit more rust in this part of the engine, but still nothing a wire brush can’t handle. With this cover off, I found the bolts for the magneto. This magneto doesn’t have points in it, the points are actually on a device called an igniter.
The igniter was used before spark plugs, and is basically a set of points inside the combustion chamber. To create the spark, the points are pulled apart at the same time the magneto is passing current through them. When the points break the circuit, the electromagnetic field in the armature windings of the magneto collapses, causing the voltage to spike and send a spark across the points.
The magneto was in need of repair so my grandpa sent it off to a friend of his to restore.
The head was next, and was the first thing that really worried me. The carbon deposits were extensive and the gasket was blown, leading me to believe that the engine may have been worked too hard and failed due to water intrusion into the cylinder. I did not suspect hydro-lock since the rod was fine and the piston was frozen halfway down the cylinder. When I was finished disassembling later on, I turned the block upright and filled the cylinder with a mix of 80% diesel fuel, 20% brake cleaner, and a touch of blaster. (Blaster is too expensive to fill a cylinder with). I then left it for about 3 weeks with the piston soaking.
Now that all the covers were off and all of the pieces that were location critical were marked, I began to remove bolts and work pieces off one at a time. The main bearing bolts were easy and came free with almost no effort. The rod bolts were a little harder, but still didn’t require a breaker bar. I pulled the main and rod caps and set them aside. The piston was stuck, but since it was half way down the cylinder, I was able to rotate the crank and flywheels with little effort and pull them off the block. With the flywheels off I had access to the governor parts. I removed everything down to the fly weight shaft and cam shaft.
This is where I made my first mistake and didn’t study the situation well enough. The nut holding the cam to the cam gear didn’t want to come off. Without thinking, I put a monkey wrench on the fly weights to hold it and tried the nut again. Snapped one of the fly weights right off. I moved the monkey wrench to the yoke and tried again, this time the camshaft broke right at the bottom of the threads. OOPS. A few weeks later when I went to remove the broken shaft from the nut, I discovered that the threads were left handed. It wasn’t even stuck! Mistakes like that can be avoided and I will definitely not assume everything is right-hand threaded. (The John Deere engineers made it left handed because the rotation during operation would naturally keep the nut tight every time the engine fired.)
A few weeks later I attempted to remove the piston. It was still frozen, but I was able to use the “brute force” method to get it out. After cleaning the carbon out above the piston, I used a lever to pry against the bottom of the rod (with a piece of pipe to transfer the force against the inside of the rod bearing seat- not against the outer yokes which would have broken). It took a 6 foot pry bar with the rod a mere 4-5 inches from the fulcrum. Putting 200-300 lbs of force on the end of that pry bar, the piston was getting somewhere between 2500-3500 lbs, and still not wanting to move. I also put an aluminum plug against the top of the piston and hit it with a 25lb sledge hammer as hard as I could. After a few hits from the hammer, I tried the pry bar again, and got the piston to move about 1/2″. From there I was able to alternate between sledge hammer and pry bar, moving the piston up and down in the cylinder until it finally came all the way out the top. I know I have a picture of it, so I will try to find it and update this post later.
With the piston free I pulled the engine block off of the base, removed the gas tank and oil pan and took the base off of the rotted skid boards. The only thing left to take apart was the head, which I left for later.
That’s the end of the disassembly. This is already turning into an epic write-up, and I haven’t even started the repair yet! Well, next up is the oil pan/gas tank repair.