Engine Failure!

ARB

Hey all,

After being serviced last year, my 7-year old Troy-Bilt push mower with a Briggs & Stratton engine has been running great... Start with a single pull, etc. Today, after a few minutes of mowing, the engine seemed to slow down a bit for a few seconds but then it seemed OK. Then, a few minutes later, it abruptly seized and the blade fell off (along with the thing that hold the blade on...it was if it had simply come loose).

I went to put the blade back on, and I noticed that the two little things that hold the blade in position (sorry for not knowing the names of all the parts) were, for the most part, sheared off. I figured I'd try to see if I can get the blade secure enough to finish the lawn and then I'll replace that part another time.

After securing the blade back on, I go to pull the cord... It pulls a little and then stops abruptly. I turned it over and tried turning the blade by hand and get the same result... It stops as if something inside the engine is hitting something. When I turn the blade the other way, it goes a little ways and then abruptly stops again. (It turns about about 60 degrees shy of one complete rotation.) It appears that something inside the engine has broken and is preventing the engine from cranking. I'm not going to have time to pull the engine apart until next weekend, but any guess as to what it might be? Any chance that I won't need to get a new lawn mower? (BTW, I checked the oil... It was a little low not dry or alarmingly low.)

Thanks!

joecaption

Take spark plug out and try to pull it over.
Remove the cover on the pull start and see if the key for the flywheel has sheared.

ARB

Thanks, I'll check it out next weekend... Can a sheared flywheel key cause symptoms this severe, though?

BigJim

My guess would be a broken rod or a busted piston.

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Jim

joecaption

Not likly but it's free to check.
What I was hoping was it was throwing off the timing.

del schisler

sound's like the rod is broken. that hold's the piston and is conected to the crank shaft. That would only let you turn tell it hit the broken rod in both direction's . good luck

ARB

Thanks for all the replies thus far... If it does end up being a broken rod, will I probably find other collateral damage as well, or is there a decent chance that I could pop in a new rod and be good to go?

del schisler

won't be able to tell you take it apart. It could score the rod journal or even bend rod?? if it was running slow you may be ok. if running wide open than different story . good luck

DrHicks

My experience with small engines leads me to two conclusions:
1. Most likely - as others have said - you've got a broken piston rod. It was just time, and there's not much you can do about it.
2. It is definitely NOT worth trying to rebuild the engine, even if you can find parts. Being a push mower, it's probably not more than about a 5 hp vertical shaft engine. You can buy new engines fairly cheap.

ARB

Thanks for tbe insight... Curious though: if it is, in fact, a broken piston rod, are you saying that the repair would likely involve a lot more than simply replacing that one part?

DrHicks

Absolutely!

A broken piston rod is almost sure to be the result of "bearing" failure on the crankshaft. Lack of lubrication led to overheating which led to melting the rod. For sure, your crankshaft would need to be replaced (truing the journals is not feasible). Also, the crankshaft carriers are almost certainly damaged. And it's entirely possible that the breaking piston rod cracked the "block" of the engine.

In addition, even if you were to get it fixed, you've still got an older used engine.


Can you give us a make & model number for that engine? Horsepower, etc.? Thanks!

BigJim

Just a guess, but I would say the engine was running pretty high RPMs if the blade sheared the pins and the blade spun off. I would say the inside of the engine is damaged to the point of not being able to repair or not worth repairing.

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Jim

ARB

Hey Doc,

It's a Briggs & Stratton 125K02-0281-E1. I believe it's 6.75 HP.

OK, so I get that I shouldn't attempt to repair it. What would you suggest? Should I buy a new short block? An entire new engine? (An entire new mower?! )

Thanks again for your (and everyone's) help!

DrHicks

Does this engine look like yours?
http://www.smallenginewarehouse.com/...e%20for%20Toro

If that's the one, it's $120 through that internet outlet place - which means you could probably get it somewhere local for about $150.

If it were my mower, and I wanted to keep using the mower itself, I'd get an all new engine. Don't even mess with any of the parts of the old one.

Then... I'd tear the old engine apart, because my curiosity would not allow me to leave it in one piece!

ARB

Makes sense... At that price, an entire engine is barely more than the cost of a short block...

Not sure if that's the *exact* one in the link, but it's certainly very similar... This one is 6 hp and has a tapped hole for Toro, whereas mine's 6.75 hp and is on a Troy-Bilt. Will check it out... Thank you again!