This is a 3-part video on my friend and I repairing our first blown engine. We got it for free from our school’s automotive program because it didn’t run. I can’t guarantee everything we did was correct or to standard, but the engine is now running very nicely. You can see that in Part 3.
Part 1: Now Watching
Part 2: https://www.youtube.com/watch?v=KEWP8xYGr5A
Part 3: https://www.youtube.com/watch?v=mrejFn7nv1c
Our diagnosis was that the engine had a broken connecting rod because when cranking the engine, the piston did not move. Upon tearing it apart we confirmed that, and had to decide whether or not it was reasonable to fix it, due to the damage and cost of repairing it. The connecting rod wasn’t too badly damaged, and the end of the cylinder wall had a slight ding. Other than that the engine was very clean and appeared to have a fairly low amount of hours on it, so we decided to buy a connecting rod and sump cover gasket and attempt to fix it. Everything went pretty well, until upon starting the engine we realized that the governor system was not controlling the engine speed. Eventually I remembered to check the adjustment at the governor arm. We speculated that this unadjusted linkage may have cause the engine failure because the RPM’s were not being limited. After adjusting that, the engine ran great on its own. We also found that after testing the pump, it had a bad unloader valve, so the pump needed work as well.