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upstatemike

K301 connecting rod

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upstatemike
The oil slinger in the K301 on my 712H broke again. When I got this machine the rod was shot, so I had the crank ground and got an undersized rod. When I put it together, I carefully torqued it to spec and placed the oil hole in the right position. When taken apart, the nuts were loose. QUESTIONS: 1) Did the nuts loosen before or after the failure? 2) If before, should I have used Loctite? 4) What other precautions can I take to prevent another failure of this sort? Any input will be greatly appreciated..Thanks..

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acjohn
Mike, Replacement rods from Kohler use posilock rod bolts. They tell you not to re-use them after they have been torqued once. You should have the rod sized with the proper clearance for the crank, install and you should be Ok. How long did the replacement rod last? I don't think you need to use loctite.

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upstatemike
John, I was very careful about the torque spec and only torqued/used nuts once. The machine shop got the proper rod to match their work(.10 under ?), but didn't assemble, and also said everything else looked ok for its age. I used it for + - 25 hrs. I also changed the oil after 1 hr run time. The current oil still looked good, except for the frags. I think this time I'll go the route as discussed by members previously and have the shop do a full overhaul; bore, piston, rings, bearings, valves, etc. and pick it up complete.

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powerking_one
Mike, Do you know the calibration status of your torque wrench? Is it possible you crossed up your numbers between ft-lbs and inch-lbs? Match marks should face the flywheel bearing plate. Are you sure the engine isn't experiencing an over-revving condition? I rebuilt lots of those K series singles in my younger days and never had a loose rod failure. It (the problem) should not be this nagging. Good luck, Tom(PK)

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upstatemike
Tom, My torque wrench only has ft lbs, so I went to my buddy's sled shop & borrowed his in lbs tq wrench, but I can't verify the calibration status. The marks were aligned properly. As for over revving, I might be guilty.. I was pushing some very large banks. Would that cause them to come loose?? I did follow the advice given in the post below & removed the counterweights... http://www.simpletractors.com/club2/topic.asp?TOPIC_ID=10058

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dvogt
If you had the Kohler rod with the studs & nuts there is a first use torque 260 in lbs for the first time you use it & a reuse torque of 200 in lbs. if you ever take it apart & reuse the rod. do you remember which torque you used? the torque wrench accuracy was also a good place to check. also torque wrenches are not the most accurate if you use them at their lowest or highest settings. its usually recomended to use a torque wrench that puts you with in the spec a little.

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charby5
Hi Mike. Inspect your crank journal.Is there more aluminum on the top of the journal (at TDC) than on the bottom? If there is. It is most likly a oil problem...inspect the dipper.was it a clean break or did it hit something to get knocked off..I have seen dippers just break off for reasons unknown..if your rod was not the posilock style rod the nuts on the rod can come loose from the hammering of the bearing babbit being spun out..as far as the balancers go.I run all my pulling motors without the balancers and have never had any problems.we run some pretty high rpms on stock rods and cranks too.up around 5500 with load so i doubt if it was from pushing high banks of snow unless you were on a incline like a hillside..hope you get it straightened out. Marc

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UCD
Counter weights are put in an engine for a reason not just for the fun of it. When they were done away with the reason for them being there was all so gone. Engine vibration can do funny things to internal parts. Don't try to out smart the engineers that put them there.

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dvogt
The balence weights were only put in for operator comfort. less vibration felt by the opertator. they really do nothing else. I've spent alot of time with kohler singles on a dyno with a vibrometer. there is very little difference in vibration between a counter balence engine and a non counter balenced engine.when Kohler did away with them many garden tractors were going to rubber mounted engines to deal with the problem of operator comfort. Kohler was starting to find out that the balence gears were starting to become high maintanace in the feild already and took them out. I deal with pulling engines also & have been working on harmonic problems for about a year that is breaking crankshafts. we used a speacialy designed harmonic balencer that we helped design. this truely does something with the harmonics of the engine. the counter balence gears just off set weight (or create a out of balence) to try to cancel out the firing of the engine. we also balence single cylender engines . there is no difference in the balence of a kohler engine that has balence gears vs. the ones that do not have them. Kohler engines are pretty poorly balenced from the factory. if they had paid more attention to that they would have never had to put balence gears in. even their flywheels (which have drill holes from balenceing) are really off.

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patrician12
It's amazing how many posts for broken rods for Kohlers.Go on ebay and there are always Kohlers for sale with with guess what?Broken rods!By the conversion kit if necessary,buy a big Briggs for much less and you will be wwwwwwaaaaaaayyyyyyy ahead.

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upstatemike
Don, 260 in lbs was the initial torque, first use. If I recall correctly, it was in the middle of the range, neither high or low end. Keeping the weights out seems to be the concensus. Marc, There does seem to be more aluminum on top. It also looks like a clean break where the slinger comes off the cap, with slight evidence of hammering on the bottom. The rod was posilock. Keith, great point, but I just acquired a K301AQS that runs good on an old Jake. I've got to pull it off and do a side by side comparison to see if it'll mount. I'm going to try to take the cheap route so the kids can still eat this week...lol... Maynard, That's what I figured initally, but after seeing the posts I removed them. It had the same rod failure with the weights in when I got it, so it seems unrelated...

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HubbardRA
My old B/S engine has a thin plate that fits under the rod bolts. Once the bolts are torqued, then you bend the corners of the plate up against the flats of the nuts to prevent them from backing off. You might try to make one of these for your Kohler.

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dvogt
I don't think you want to put the lock plate in , Problem is its hard to determine if the nuts are actually coming loose or if the studs streach a little for some reason then you have the apearence that the nuts are coming loose. if the rod was starting to tranfer aluminum to the crank & it looked like it was hammering the studs could have been streached . it don't take much streach to make the nuts loose.

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arjr111
Mike, I have seen some other posts, addressing the same problem. I have also read, that some people grind a little off the end of the oil dipper, before installation to avoid this problem.

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upstatemike
Rod, Tecumseh uses the locking tabs also. Seems to work well. I've never had this type of failure with Briggs or Tec. Don, Possible timeline of failure: Studs stretch, nuts loosen, slinger hammers & breaks, no oil at rod/crank, excessive friction/heat at rod/crank, aluminum melts ??

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charby5
Mike Alot of the old Jakes/Fords took what I call the (cub style) oil pan and a few models incorped mounting for their front axels in the pans. Ive even seen these pans welded to the frames. If yours is like this, the engine itself will work but you'll need the flat cub oil pan,(the pan bolts upward into the block).You will have to drill new mounting holes and space the engine up enough to align the shaft and get the pan up off the mounting plate of the tractor(not really as hard as it sounds). Simp/AC uses the flange block or what some call the universal block(the pan is threaded and bolts go downward through the flange part of the block)alot of the Wheelhorse used this flange style block also.. hope this helps . Marc.. Marc..

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CarlH
When the flipper broke off the rod cap on my 16 HP Kohler (K341S), the lack of cooling from the oil splash caused expansion of the rings until they went solid, locking up the engine. Fortunately, I had noticed the engine loading up from the tight rings and was in the process of shutting it down when the lockup occurred. The rod didn't seize to the crankpin. It left an unusual horizontal groove in the cylinder wall that required boring to remove. I really have never figured out why the flipper broke. One hypothesis I have is that I had previously mistimed the balance gears since on that rebuild I struggled to get them timed properly. Carl

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dvogt
I've seen Kohler piston skirts break , when the broken part comes down it will usually takes the dipper off if it makes it past the lower part of the cylinder as the rod comes by and the rest is history. the skirts like to break on them when they start to get loose and slap back & forth. its more common on the 16s but I've seen it in 12& 14 hp. Kohler went to the Mahle style piston because it was a better design. I usually buy the Mahle style piston& rings & put them in the older engines as a nice upgrade

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upstatemike
Marc, Thanks for the tips. I'm hoping to get some time this weekend to look at the mounting. Yes, the skirt was broken when I took it apart. Maybe that broke the slinger. Art, I considered grinding some of the slinger off when I last put it together after looking at the prior failure. I think I will this time if I put this back together. Don, Thanks for the piston upgrade tip. Carl, My Son initially took the motor apart when we got it and pulled the counterweights out before I could photo the placement. We left them out when we put it back together. Thanks for all the input. The wealth of knowledge and experience of this Club's members is astonishing. Thanks again... Mike

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powerking_one
Mike, I would strongly agree with Don and Marc on the broken piston skirt theory being the cause of the rod failure. There's very little clearance between the dipper (at BDC) and the pan; say ~~ 1/2 the thickness of a piston skirt? You may want to look for that tell-tale "impact" mark of the dipper hitting the skirt piece. If a match is found, then there's your root cause of the failure. Not skirting the problem, Tom(PK)

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Dutch
Don (dvogt), Some trucks use "stretchable" bolts on parts like flywheels. I've had some bad experiences with them, and have replaced them with regular bolts. Have you ever replaced Kohler rod bolts successfully?

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