ray...
The happy Nada Farmer, finding new ways to make the same mistakes for 57 years.
Keep coming back , I'm sure I'll screw up something else soon.
Poor Old BobCat !
Well, at least the Kohler Twin Engine.
The Bobcat Skid Steer is under the wrench again. This time, due to a big bang and a severe lack of power, which was caused by another thrown rod. It happened in such a way that the engine, a twin cylinder, would still run. But obviously, it wasn't good for it, and it had a terrible lack of power. So when I finally got to a point that I really needed it to work, I took it apart to find out what was wrong with it, and get the parts to repair it. This is probably the last time this engine will be rebuilt, the parts are getting hard to find, and the expense is getting into the neighborhood of a new machine. Or at least a replacement engine. The explaination was getting so detailed, as to warrant it's own page, so here we are.
Continued from Farm Page 52, Some close-ups of what stopped me the night before the pour. There is a crack here In line with the wrist pin. I didn't find it, until I had the magnifiers on. This alone is scary enough to warrant the replacement of the piston itself. But I have a hard time convincing myself to spend the money, until I remember what a pain it is to disassemble the tractor enough to get to this point of access to the engine. I am suppossedly in possession of the last two rods for this engine that will work with these pistons. And again I am going to have about $700.00 dollars in this old Kohler twin engine. But if I do this right this time, it should outlive me. Which would be just great. But, we will see how that works out.
This crack (below) was pretty obvious, but I hadn't thought to look for it , but it became noticeable due to a deformity I noticed in the side of the piston. There is an obvious scrape where the crank hit it at some point. At the end you can see the aluminum deposited on the crank.
The bottom of the piston that keeps it from wobbling in the cylinder is called the skirt, for rather obvious reasons when you look at the design of the entire piece. The initial damage I noticed was due to the broken rod getting whacked into the inside of the piston, when it was chopped off by the turning crank. I was checking for the required clearance on the old pistons, which showed some wear in this area, to see if it was within the tolerance for the skirt clearance to prevent "piston slap".
Below are a couple pistons that are representative of the rods that have been shortened in this engine over the years. The rod on the left, stopped the engine when it broke. The rod on the right got chopped off and the engine continued to run.
The chopped off aluminum rod has hit the skirt hard enough to leave a mark inside and noticeably deformed the piston's skirt.
The crank has aluminum imbedded in it from whacking the piston skirt. I spent a couple hours cleaning the journal, removing the "friction welded-on" aluminum residue from the rod.
So using the expertise I developed during the small engine building for the volkswagens and the go karts, I hope this engine will be much more durable and effective this time around.
Click here to go back to FARMPAGE 52! As Promised.
Man, are we happy out here!
