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Pulled the 10HP K241 apart in my 79' C-101

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So the old Kohler K241 in my C-101 seemed to have developed a quiet knock once it got warmed up and under load.  Since, to my knowledge, it is the original engine and has not been touched other than routine maintenance, and I need to replace some gaskets because of oil leaks, I decided to pull it out of the tractor and tear it down and inspect it.  After putting a mic to everything the only thing I can tell it may be, is the rod journal on the crank, it is slightly out of round but I think still with in specs. Granted, I don't have expensive measurement tools, my micrometer is a dial mic and only goes out to .001.  So the crank rod journal spec is 1.500 and that is what it measures one way and 90 degrees to that it measures 1.499. See specs below.  I did check the valve clearance after tearing it down on both valves, The intake valve was good at .009 and the exhaust valve was over at .020 so I brought it down to .018, would the exhaust valve being over gapped ever so slightly have been the knock that I was hearing? At this point I think I am planning on honing the bore, installing new rings and putting it back together.

 

Here are the specs and numbers;

Piston  New spec. 3.2432" wear limit 3.238

My piston 3.240

 

Cylinder bore parallel to stroke

top 3.249

Middle 3.249

bottom 3.250

 

Cylinder bore perpendicular to stroke

Top 3.250

Mid 3.249

Bot 3.249

 

My Rod journal measured inline with rod length

1.500

Measured perpendicular to rod length

1.500

 

Crank rod journal spec

New 1.5000/1.4995

max wear 1.4990

Max out of round .0005

 

My crank rod journal

measured centered inline with bore (Piston rod at bottom of stroke) 1.499

Measured off set from bore (piston rod half way up/down stroke) 1.500

 

Like I said, my mic only measures out to .001 so the crank rod journal measurements are what may be in question at this point. But, even so, I don't see anything that explains a quiet knock under load after it is warmed up.

Any ideas?  Oh yeah, there was quit a bit of carbon build up on top of the valves, around the valves, on the top of the piston and on the cylinder head. Towards the to of the first photo you can see an entire ridge of carbon along the gasket surface between the exhaust valve and piston.  The third pic is the inside of the oil pan after just taking it off, that is how clean the inside of a 38 year old engine can be when it is properly maintained. You could have white glove tested it, I couldn't believe it!

 

 

 

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Took it to a show and swap meet a couple of weeks ago and had a great time, funny thing was is John Deere was the featured tractor this year and as you can see in the pics they were out numbered.  It was only the second year for this show.  It is held in Osceola, Iowa, and a couple of fellow Wheel Horse enthusiast got it started last year.  We had about 25 more machines this year, so it's growing.

 

Okay, picture size limits are fighting me so will add another post.

 

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Okay, apparently I can't post ANY more pictures at all! Whats with that?!

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You need to be one a forum supporter. Non supporters are limited.

 

its only 20 a year

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The motor looks clean. That is not an original motor to that tractor, so it is not 38 years old. Could be why it's so clean! 

Original Kohler for the C-101 woild hsve balance gears. Can't tell from the pics, but doesn't seem to have studs for the gears. 

IF your micrometer is calibrated,  your measurements seem to be close to the wear limits...still good. 

The slight knock may be piston slap. Nothing that a good hone, new piston and rings won't fix. Just my opinion  :handgestures-thumbupright:

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1 hour ago, SRB said:

it is slightly out of round but I think still with in specs.

Best way to check a rod and crank assembly clearance is to use Plastigauge. It will check the two components as an assembly, not just one piece.

Image result for plastigauge

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1 hour ago, oldredrider said:

 

Original Kohler for the C-101 woild have balance gears. 

I believe I'm mistaken. K241AS Kohlers did come without balance gears. My apologies. 

I still think you've got a good solid engine that only needs some TLC.

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1 hour ago, oldredrider said:

The motor looks clean. That is not an original motor to that tractor, so it is not 38 years old. Could be why it's so clean! 

Original Kohler for the C-101 woild hsve balance gears. Can't tell from the pics, but doesn't seem to have studs for the gears. 

IF your micrometer is calibrated,  your measurements seem to be close to the wear limits...still good. 

The slight knock may be piston slap. Nothing that a good hone, new piston and rings won't fix. Just my opinion  :handgestures-thumbupright:

Considering the history of the tractor that I know and the original documentation I have for the tractor, engine, mower deck, and snow thrower, including the original warranty cards still in the original letters and envelope I personally do believe it is all original.  Especially considering how meticulous the original owner was, I can't see him changing the engine and putting the original SN decal engine shroud on a different motor. If he changed the engine, I would have all the info for that engine.  This is model years when they used K301 blocks bored to the K241 specs in order to use up end of the run production inventory, so it has the K301 casted block.

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2 hours ago, 953 nut said:

Best way to check a rod and crank assembly clearance is to use Plastigauge. It will check the two components as an assembly, not just one piece.

Image result for plastigauge

Is there a technique one can do with plasticgauge that checks out-of-roundness of the rod journal? Also I have not found anywhere that says to use plasticgauge on bearingless rods like these small engines use.  Does one use it on these small engines like you would on engines with bearings?  This is the first small engine I tore into with the intent of rebuilding it.

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1 hour ago, oldredrider said:

I believe I'm mistaken. K241AS Kohlers did come without balance gears. My apologies. 

I still think you've got a good solid engine that only needs some TLC.

No worries, and your right, regardless, it is a solid motor.

2 hours ago, Aldon said:

You need to be one a forum supporter. Non supporters are limited.

 

its only 20 a year

Hmm....interesting. So does that mean once I reach my limit I can't post any more pictures ever, unless I become a "supporter"?

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7 hours ago, SRB said:

does that mean once I reach my limit I can't post any more pictures ever, unless I become a "supporter"?

Unless you defeat other photos this is true, Storage space on the site is an expense we all share as supporters. Without :text-coolphotos: it can be difficult to tell the story and share the journey.

7 hours ago, SRB said:

a technique one can do with plasticgauge that checks out-of-roundness of the rod journal? Also I have not found anywhere that says to use plasticgauge on bearingless rods like these small engines use.  Does one use it on these small engines like you would on engines with bearings?

In the case of small engines the rod is it's own bearing. I use two strips of Plastigauge, one on the bottom as shown in the picture and one running diagonally at the side, then torque the rod bolts, remove the rod and check.

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1 hour ago, 953 nut said:

Unless you defeat other photos this is true, Storage space on the site is an expense we all share as supporters. Without :text-coolphotos: it can be difficult to tell the story and share the journey.

In the case of small engines the rod is it's own bearing. I use two strips of Plastigauge, one on the bottom as shown in the picture and one running diagonally at the side, then torque the rod bolts, remove the rod and check.

Thank you for the tip 953 nut. I am excited to get this back together.

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Piston slap is generally more prevalent in a cold engine. Did you measure the piston at the right place as shown in the book? Slap rather than knock. I would also check the piston wrist pin, you cannot really do that with your .001 mic. I can tell the wrist pin by feel.  I would also take the crank to a machine shop and have them measure it. In your measurements you list a 1.5" crankpin measurement and a 1.5" rod size. That measurement cannot be correct, even if new. I do not like plastigage to check wear. It works great unless you are out of round. My limited Kohler knock when warm experience has always been excessive rod to crank clearance. Warning, if you replace the rod and piston assembly, if the new replacement does not weigh the same as the old, you will pick up some vibration. 

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Just my opinion here ----

Having read your descriptions and seen the pics of the engine, I would got to ebay and choose one of the - very inexpensive - 'rebuild' kits. (there are MANY of them) My guess is that you have some slight wear on your existing rod, with the crank being OK  (steel against aluminum). and a new rod would correct that, and you would have the benefit of getting the piston/rings along with gaskets, etc.

 

I have used several of the kits and found them to be perfectly good...

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