Test drive

After doing some carburetor adjustments and minor hood repairs, I took the Little Mule out for a test drive. The engine ran great! I need to tweak the governor a bit, but that's an easy one. Here she is with everything in place, ready for work.

First start

This was the big moment, just before turning the key for the first time. A sound recorder is set up on the tripod ready to capture the event.

A sound clip of the first start is available here (MP3, 1.9MB). Yeah!

Final installation

After lifting the beast in and loosely attaching the bolts from underneath, the next job was to align the block with the transmission input shaft. I performed a partial alignment only, meaning I just ensured that the crankshaft was pointing in the same direction as the transmission shaft. A full alignment would have also ensured that the engine was at the right height - but I don't have the tools and equipment for that.
In the photo above I've got a level on the transmission shaft (visible to the left) and another level on the cylinder head (at the top right). It was off originally, the engine block was pointing up by about 5 or 10 degrees. This would have been another big contributing factor to the broken spring pin problem, certainly. Using washers at the front of the block, I corrected the angle - it's as close as my simple measuring tools can get it.

Just about everything is in place now, gas tank, cooling shrouds, starter/alternator, clutch is adjusted, new fuel lines. Oh and engine oil too (very important).

Linkage confusion

I installed the carburetor and some of the linkages that go along with it, then became stumped again. I wish I had taken a photograph of how it all was assembled originally, but I hadn't. I'm going from memory of years ago when I worked on a similar engine on our farm. Oddly though the memories came back and the mechanisms were familiar.

I picked up the new oil pan gasket today with the clutch parts, and torqued-in the pan. The engine is now ready to go back in to the tractor.

Parts in! -> clutchwork

I picked up the clutch parts today and was able to re-assemble it. The picture above may help to describe what I was trying to explain in one of the recent posts - you can see the three new "special bolts" as well as the shiny new thrust button in the centre. This was just a trial fit to make sure that the new parts mated up properly with the old stuff.


The first piece to go on is shown here - the crank pulley/clutch receiver. This is the part that was damaged, but happily it seemed to go back just fine. To locate the pulley on the shaft I temporarily installed the starter/alternator, but it's not shown in this photograph. The starter/alternator adds about 20 pounds to the engine which is already a hefty 110 pounds by itself, so I'll install that part as late as possible :)


Next is the clutch support bearing. This is a new part, the old one was in tough shape. You can see the main body of the clutch to the left of the photo. I was a bit stumped here, trying to figure out how this thing was supposed to go back together as I couldn't remember how it came apart! Luckily my brother Dave purchased the operator's manual recently and I was able to refer to it for a picture (sadly though the picture was all it offered to help me, other than to say that owners should refer to a qualified IH shop to service the clutch. LOL! The picture was enough.) Since I just recently held the piston in my hand, I guess I'm about as qualified as we're going to get on this project :)
The way the bearing is mounted is a little bit odd from a traditional mechanical viewpoint, but by process of elimination I think I figured it out.

The photo above shows the PTO clutch fully assembled and ready for work. The tiny thrust button is dying to be pushed.

Stripped threads update

The great service you can get from small local businesses never ceases to amaze me. I spoke to Bill at my favourite local machine shop who do a lot of work for the company that I work for, and he was very accommodating. He said "Heli-coils, in aluminum, holes already there? No problem. When do you need it?" Nice. Very nice. Dropped it off at lunch and picked it up after work. He put inserts in all four holes, in the photo you can see the fresh shiny new threads in one of them on the lower right. Cost? $10. Hard to beat.
When I removed the oil pan, the brand new gasket was destroyed of course, so I can't put it back on until the new one arrives (ordered Tuesday from the local IH dealer, should be in Friday).

Carburetor cleanup

The carburetor combines gasoline with air to create the fuel mixture that burns in the engine. I took it apart today fully expecting it to be full of grime from old fuel sitting in there year after year, but was pleasantly surprised - it was as clean as a whistle! All I had to do was wash off the outside oil and grass grunge that had accumulated, a half-hour job.

A minor set-back and some perspective

It's worthwhile mentioning at this point that last summer, after an initial investment of just $200, this tractor cut grass nicely. There were a couple of problems with it though. One was that the engine was old and tired: it burned oil, blew stinky smoke out the exhaust, was finicky to start when hot and had an annoying habit of backfiring. Those problems will be solved with the service rebuild I'm finishing up now.
The other problem this tractor had was that the spring pin that connects the engine to the transmission input shaft had a tendency to break. Like every 20 minutes. It even broke while I was driving the tractor home after purchasing it! :) Actually that first time there wasn't a spring pin in there at all but a POB. I replaced it with a spring pin and thought "great - that problem is solved!!". Not quite. The deeper issue became apparent when I removed the engine from the frame last fall - only three of the four bolts that hold the engine in the frame were there, and of those only one was tight. That improper mounting let the engine slop around in the frame and certainly contributed to the broken spring pin problem (I hope that was the only cause, but that remains to be seen).
The set-back was that when I was tidying up the threads in the engine, getting it ready for mounting, I discovered that the threads in one of the holes was totally stripped. Three out of four isn't going to cut it, so the thread has to be repaired. I chose to use a Heli-coil insert (a relatively cheap and better-than-new repair) but unfortunately that means I need to pull the oil pan off the block again (where these threads are) in order to do the work. This will take a few days. Plus I don't have the tools to make the repair myself: I bought a box of inserts today, but after pricing the full repair kit ($90 for a special drill and tap) I couldn't justify that. I'm hoping that my friendly machine shop will do this for me either for free, or for a token fee. Depending on the cost, I may have all four done at once and then the engine will never vibrate loose again.

Tidbit: Did you know that 250,000 Heli-coil inserts are used on each Space Shuttle? Yes, that's one quarter of a million. Same with Boeing's 747's: each one has over 250,000 of these inserts. Cool.

Clutch update

The PTO clutch that drives the mower was one part that I whipped off last year and hadn't paid too much attention to until last night. This part underwent some hardship at some time in the past (recall from an earlier post the picture of the crankshaft end that was all chewed up - that's where this clutch mounts). It's hard to tell what happened, doesn't really matter at this point. No matter how nicely the rebuilt engine runs, if we can't get power to the blades then this whole effort will have been for naught!
I looked more closely at the clutch and noticed that it had been repaired; there are three special bolts in it, each of which has a dish-shaped head that holds a matching lever in precise location. The three levers keep things centred when the clutch is engaged and disengaged. At some point two of these special bolts were replaced with POBs (plain old bolts), and those didn't keep the levers in the right place so only one of them was actually working. Anyway, I ordered a set of replacement bolts ($7 each) and will be able to re-use the levers, they're fine. There is also a "thrust button" at the centre of the clutch that the three levers engage with - this is the mechanism's G-spot, except that when you push on it, the mower stops working. The thrust button fell out when I disassembled the clutch because the threads on it were gone (broken off). I ordered another one of those as well.
All these parts should be in by the end of the week and won't hamper the progress getting the tractor back together.

Getting ready to re-install

The engine is bolted to the frame from the bottom, and two of the bolts are obscured by the front axle assembly so I had to drop it out of the way.



The pressure washer helped to dislodge 35 odd years of accumulated grunge.


This is what the engine looks like now. Flywheel and shroud are back in place. The new replacement hub and grass screen look pretty good against the new paint job.
Valves are back in and adjusted, and the points assembly (lower left) are in and adjusted. The cylinder head is in place but not torqued yet -- I'll wait until the block is in the tractor for that because it'll just be easier.

Ready for the top work

The engine is now ready for its valves. That will happen another day!

Re-assembly: The Heart

Here is the new piston with the rings installed. The picture is blurry, and that's appropriate because that's how my mind felt after trying to interpret the Chinglish installation instructions that came with the ring kit. Yikes! The Kohler manual, unfortunately, doesn't address these details as the rings come in such a wide variety in the "service" form. I think I got it right. I hope I got it right. Nothing good will happen if I didn't.



Here is the rod mated with the piston. Nice and shiny.




And here I'm using my Princess Auto ring compressor to squeeze the rings down to size so I can fit the piston/rod assembly into the block. The ring compressor is one of the few "special" pieces of equipment I had to purchase for this project. Without it, it would have been nearly impossible to get the piston installed without damaging something. This is one part of the rebuild process where you don't want to cut corners.



Alrighty! Piston and rod are in, and the rod cap (with the long oil dipper you can see here) is torqued to spec. I decided to coat the oil pan gasket surfaces with a gasket compound to ensure it doesnt leak. The machined surfaces were quite a bit rougher than I would have liked (though probably still fine). The compound is just cheap insurance. This is the last time most of us will ever see the inside of this engine, I hope anyway :)