Kohler K321Connecting rod

[Kaden]

Okay I'm rebuilding a Kohler k321 but I have come to a halt. I rebuilt the engine torqued the rod to 50ft lbs. got it back in the case 444 that it goes in I started it and it ran good till about a hour of running it then I heard a knock... I shut it down and turned the crank by hand and sure enough it had enough slop I could feel it. I have now completely tore the engine down and now I'm looking for the torque spec on this rod. If you look in the manual it states on a k321 265 ft. lbs. or close to it but at the very bottom right corner it says models before a certain serial number are 45-55 in super small ink and that's all it says it doesn't say what that torque spec is but the serial number is 5310534 for the engine I'm rebuilding and I've started to try to torque it to 250 and that seems like a lot matter of a fact I ran a test on the old rod and the bottom piece of the rod broke. I'm at a loss any help is appreciated.

 

[wore out]

Okay I'm rebuilding a Kohler k321 but I have come to a halt. I rebuilt the engine torqued the rod to 50ft lbs. got it back in the case 444 that it goes in I started it and it ran good till about a hour of running it then I heard a knock... I shut it down and turned the crank by hand and sure enough it had enough slop I could feel it. I have now completely tore the engine down and now I'm looking for the torque spec on this rod. If you look in the manual it states on a k321 265 ft. lbs. or close to it but at the very bottom right corner it says models before a certain serial number are 45-55 in super small ink and that's all it says it doesn't say what that torque spec is but the serial number is 5310534 for the engine I'm rebuilding and I've started to try to torque it to 250 and that seems like a lot matter of a fact I ran a test on the old rod and the bottom piece of the rod broke. I'm at a loss any help is appreciated.

You need to learn the difference between foot pounds and inch pounds!

The "specs" are in INCH POUNDS, divide by 12 to get foot pounds, meaning the torque will be in the 16-25 foot pounds area, depending upon the details of the rod you have!

Best to use an inch pounds wrench, as those are low torque values for a big foot pounds wrench to be accurate.

https://resources.rehlko.com/enginesus/pdf/tp_2379.pdf

Link to Service Manual (in .pdf format). Can be downloaded for FREE or print the pages you need.

 

[Kaden]

Yup that would be my problem I hate when you know better but can’t find the problem then it’s something simple but it still doesn’t explain what the little blooper is at the bottom of the manual stating before a certain serial number 45-55 I’ll see if I can post a image up

 

[Kaden]

Where I circled in red it says 45-55 ft lbs and the one I’m working on is before that serial number but it doesn’t really state what that torque spec is for

 

[wore out]

Where I circled in red it says 45-55 ft lbs and the one I’m working on is before that serial number but it doesn’t really state what that torque spec is for
View attachment 122073

If you look closely, there's a circled "6" ahead of that torque specification ("Note 6") which leads you to the flywheel nut/bolt torque. At that point they changed from the crankshaft having a threaded end that used a nut to retain the flywheel to tapping the end of the crankshaft internally and using a 3/8" fine-threaded BOLT to retain the flywheel.

 

[Kaden]

If you look closely, there's a circled "6" ahead of that torque specification ("Note 6") which leads you to the flywheel nut/bolt torque. At that point they changed from the crankshaft having a threaded end that used a nut to retain the flywheel to tapping the end of the crankshaft internally and using a 3/8" fine-threaded BOLT to retain the flywheel.

Got ya thanks

 

[T.R.K.]

Is this a new connecting rod? Was the crank reground? Did you mike the crank or check the bearing clearance when you put it back together? My machine shop goofed up once and the crank was something like .003 off the spec. for a .010 undersize rod.
Also, are you using the old piston? Is there any noticeable play in the wrist pin between the piston and rod? That can also cause a knock. A really worn piston skirt can also cause a knock as it goes up and down the cylinder.
If this was the old rod, did you check the bearing clearance with plastigauge or measure the crank with a micrometer?
Although I am thinking Kohler permits more that .0015 clearance between the rod and crank in their specs, In my experience you can hear it knock if there is more than .0015 clearance.