My question is a hybrid of lawn tractor / engine repair.
I was given a 12-1/2 hp Craftsman lawn tractor with a 38" deck. I had one almost identical to it years ago; I gave it away. Now I need one, and one has appeared! (In case anyone cares, it's a Briggs & Stratton engine in a Model 917.252450 tractor.)
Anyway, the tractor had two known problems (and maybe a third). It was leaking oil like crazy, and subsequently would not crank or start. There may also be an ignition timing issue -- more on that later.
The electrical problem was too trivial to even enter. It starts and runs.
The leak: This is a vertical shaft engine, bolted to the frame at four corners. An assortment of machine screws hold the two halves of the crankcase together. One screw has loosened. It's the rightmost, rearmost one, pretty much next to the dipstick. I tightented it up, put oil into it, started it up, and it seemd ok. I went and mowed for a while in front of the barn, and then looked under the hood. Lots of oil. The screw had loosened again.
So here's the thing: That screw is captive. I can't take it out, because there is not enough clearance between the crankcase and the frame. Not enough thread shows when it's loose to be able to put threadlocker on the threads -- the ones that you can see are never engaged, I believe. Now, the tapped hole on the other crankcase half -- the upper one -- is a through hole. I'm thinking that I could get the screw close to seated, then pour loctite into that hole, then finish tightening it. There's probably so much oil on the threads that nothing will grip -- but who knows?
Alternatively, I can remove the engine from the frame, and then either clean it up, apply threadlocker, and torque it to an appropriate value, or split the cases and replace the gasket, or loosen the cases and slip in some 'gasket in a tube' RTV product, or permatex, or ??
Any suggestions? What good solution am I overlooking? What would you do if it was yours (and paying someone else to do it was not an option)?
The other half question is about ignition timing. I've never fooled with the timing on an engine like this. How do you check the timing? I have a sense that it's too advanced. I'm old, and that's mostly 'intuition.' It kind of hammers when I advamce the throttle, and it kind of hammers when it gets loaded (driving fast into tall grass). I suppose one test would be to put some higher-octane fuel into it and see if it gets better. I haven't blown a hole in a piston since 1969, and I'd like to keep my record intact!
Thanks in advance for any and all insights,
Paul in Wisconsin
