Broken connecting rod?
 

Was having a bad day with my 126 yesterday. Doing a little food plot plowing and weld broke on my plow sleeve hitch. Started heading home and made it almost to the shed when it started blowing white smoke and losing power then a bang and it died. Turns over freely but the piston doesn't move. Any free download links for tearing the motor apart? How does it unhook from clutch? After I unbolt the 4 mount bolts under neath will it slide forward and pull out from clutch or is there more to it then that?

Download the service manual found on this site. Besides the 4 bolts you have to disconnect the throttle cable, choke cable, etc etc.

ok thanks. Any idea what would cause the rod to break besides old age? It was only being ran at half throttle.

No oil......

I bought a 129 a few years back that had had the engine replaced with a black 12 hp Kohler engine. I assumed it was a service replacement. The dealer said the engine was put in the tractor the year before so it wasn't an old engine.

I took the engine apart. The rod was broken just above the big end. Crankpin was perfect so I don't think the rod broke from lack of lube. I really have no idea why it broke unless the rod was just defective.

I put a new rod in it, put it back together and it's run great for years.

well I checked the dipstick and it has oil but is a little low. I have been searching this site for the downloadable manual for the engine but I can't find it even with the search feature so If someone has a link to it I would appreaciate it. Going out now to see what I can figure out without the manual.

It's in the technical section. Under "tractors" 3rd page. Kohler "K" series engine.

Here, just so you don't have to look again.
http://www.onlycubcadets.net/forum/s...ead.php?t=4646

Thanks for all the help. I got the engine out and oil pan off. The connecting rod is broke and it did leave some burrs on the crankshaft. If I lightly sand the burrs down with a dremel is it possible it will still work with a new rod? I didn't see any stamping on the piston top so I am thinking it is stock bore and the cylinder walls are scratch free. The engine is a K241AS I was told it was not the original engine. I see the 241 is a 10hp is it possible that the flywheel cover with the model number was from a 241 but the rest of the motor is a 301 or would it not fit? If it is the 10hp it has plenty enough power for me I just need to know what model I need to order parts for. Is there a number on some other part of the block I can look for? I did download the manual and am reading that also.

If the big end of the rod broke and it banged the crank journal, you may get away with knocking off any HIGH spots and be good to go. If that big end seized due to lack of lube, you may not be so lucky. Measure the crank pin and see if it's still round.

I'm sure you'll get other advice.

Please, don't use a dremel on your crankshaft....... just take it somewhere and get it cleaned, measured, ground if necessary, or polished. You nick that crank with the dremel just right, and you'll be back where you started with a broken/ seized rod.

It could be a 10hp or a 12. The tins and blocks are same size, just different bore and crank. The block is "stamped" (raised cast numbers actually) on the PTO end either with a K241 or K301. Be careful though, there are some 10hp motors (K241's) that are marked K301. So, your better off using crank numbers, or measuring the bore.

Also, Roland says that rods can break just from age and fatigue.
:bigthink: Hmmm, that sounds like me! :biggrin2:

thanks I think it was due to low oil tho judging by the crank. Unfortunately I already cleaned up the crank bets I could before I read the post not to. I really don't know how to take the crank out anyway and I have been trying to view the pdf manual but my computer keeps freezing up and won't load the pages so no luck there. Am I wasting my money by just replacing the connecting rod if the crank is slightly out of round or not polished completey smooth?

I'm sure others will disagree, but I say yes. I've built a lot of motors, and with the price of Kohler parts..... I wouldn't do it. Now, I'm not going to preach about the "right" way to rebuild at this time, but if the crank is out-of-round or has any burs on it, it's just going to eat that new rod. And that, is a fact. If this motor had a pressurized lube system, you might get away with it. But, if there is anything a "splash lube" motor needs, it's a tight, true and clean rod journal!

I agree!...

X3 on the rebuild. It's one of them "You never got time to do it right but you always have time to do it over" things. My shop teacher in high school back in the 70's used to preach that to us all the time.

Only thing I would add to your shop teacher's sermon is, with experience comes a determination of what will go and what won't. The money difference can be huge.

It is very easy and safe to preach what is the "right" way. Unpopular to preach a "maybe".

Niteblaster I don't know where in NY you live but I have a 241 block that has a good crank and rod in it. It is yours if you want to pick it up.

when a engine is run low on oil to clean the alum off the crank use muridic acid then mic it to make sure its in spec

X2

Dremel is a big no-no on a crank journal.

Thanks again everyone and Cubs-n-Bxrs I sent you a private message I am interested in that 241 block that you have. Please let me know if you did not get my private message.

Well its up and running again thanks to cubs-n-bxrs !

Great news! :beerchug:

X2!:beerchug:

I'm glad the engine worked for you. Just curious how does it run? Always nice to help out a fellow cubber.

Seems to run ok. No smoke and idles nice and the oil is full!