WallaceRoger
Member
- Joined
- Apr 26, 2020
- Threads
- 5
- Messages
- 14
I had an interesting experience with a Lawn-Boy series F engine from a mower built approx 1989. The mower itself was in really nice shape physically and came to me at very low cost as nonrunning, so I figured probably just old gas in the carb. Sure enough I cleaned that up, replaced a leaky fuel line and it started up and ran after a few pulls. Ran nice. Shut it down and put the bagger chute on. I started it up again next day and heard banging, so figured the blade is maybe hitting the chute somehow. Checked that and it was (chute is from another Lawn boy), so I modified it a bit to fit. Started and ran good, tested on the lawn too. I figure well enough so I listed it for sale.
I did a final check morning of the sale and it was suddenly running like crap and the banging was back! It then totally died. Tried pulling the cord a bit and it's not moving... not good. Anyway, after determining the pullstart is fine and the safety brake isn't engaged, I pull the engine and remove the bottom of the case, one of the needle bearings and some other junk falls out (not a great sign), and I see the engine is now stuck. There's a ton of slop in the crank and I also see the connecting rod bolts are loose! initially I thought maybe someone else was in there before me because they're hex bolts and I've never heard of using hex bolts in this application... usually it's machine bolts with locking plates. But watching some teardown videos on Youtube shows they indeed used hex bolts on series F engines for this. Pretty dumb in my opinion.
What are my likely culprits? The engine wasn't especially dirty when I got it, so although I'd suspect overheating at some point in its past, I don't think that's it. Would running straight gas cause this? I can't decide if it seized first or if the loose bolts caused it to seize. I was using a normal 32:1 mix in it, the tank was bone dry when I brought it home.
I did a final check morning of the sale and it was suddenly running like crap and the banging was back! It then totally died. Tried pulling the cord a bit and it's not moving... not good. Anyway, after determining the pullstart is fine and the safety brake isn't engaged, I pull the engine and remove the bottom of the case, one of the needle bearings and some other junk falls out (not a great sign), and I see the engine is now stuck. There's a ton of slop in the crank and I also see the connecting rod bolts are loose! initially I thought maybe someone else was in there before me because they're hex bolts and I've never heard of using hex bolts in this application... usually it's machine bolts with locking plates. But watching some teardown videos on Youtube shows they indeed used hex bolts on series F engines for this. Pretty dumb in my opinion.
What are my likely culprits? The engine wasn't especially dirty when I got it, so although I'd suspect overheating at some point in its past, I don't think that's it. Would running straight gas cause this? I can't decide if it seized first or if the loose bolts caused it to seize. I was using a normal 32:1 mix in it, the tank was bone dry when I brought it home.
