I stopped by the lawn and garden section mainly out of curiousity . I needed a
prime mover for my generator project and wanted to look over a few prospects.
What happened when I got there was the furthest thing from my mind. It went something like this:
I asked an attendant about some used lawnmowers he had in a corner of the yard. The attendant told
me that all of the lawnmowers were in need of repair. I offered to buy a couple of them
and the attendant told me that If I could take all 5 lawn mowers, I could have them for $20.
I said, "you've got a deal"!
My reasoning is that out of the 5 lawn mowers I purchased, I should get at least one fully functional lawnmower engine.
I picked two of the 500 Series lawn mower engines for my generator project. They are 158cc engines that develop 5 ft. lbs. of torque. That sounds impressive doesn't it? I need to remind myself to ask someone one day just what that means! Anyway, the one on the left has no compression, a blown piston or rod maybe, and the one on the right has a bent shaft of which I hope will be a supplier of good parts.
I started the small engine tear down by removing any remaining oil and then proceeded to remove the oil pans. I exercise care when removing engine parts to avoid damage as much as possible. Some engine parts come away freely while others try your patience. When I looked inside the small engine that had no compression, I was shocked by the devastation I saw in the crankcase.
I'm still scratching my head over this one. The piston connecting rod had completely shattered, I'm talking about bits and pieces people. How could it shatter so violently without rupturing the case or warping the drive shaft? I wonder if someone tried to start this small engine with ether and applied too much? In any case, someone was lucky and, a "Thumbs Up" to the engineers at Briggs & Stratton, the crankcase contained the explosion.
I salvaged the best parts from both small engines and assembled them for the rebuild. I was happy to see that the piston from the bent shaft engine was in like new condition. Neither one of these small engines had been run very long, they just failed from neglect.
Prior to placing the piston in the bore, I cleaned the cylinder wall looking for cracks or other imperfections. This bore is in great shape. I then coated the piston and cylinder wall with plenty of oil before inserting the piston in the bore.
After the piston connecting rod was capped and torqued on the crankshaft journal, I replaced the lifters, camshaft-camgear and the oil slinger. I lined up the timing marks on the camgear and the crankshaft gear for proper timing. I used "Form-A-Gasket" on the oil pan flange to make a fresh gasket and replaced the oil pan.
Not bad for a $20 investment. Actually, it gets even better. Out of the five lawn mower engines I purchased at the shopping center, I have two small engines working, one that needs a piston and one is being converted to work as an air pump. I just can't pass up a deal.