Tearing further into the 107

[Cubcadet_107]

After almost 2 years, it is time for me to bring this thread back. The k301, as worn as it is, has been doing alright in the 107 and I have been in no rush to do the work to the k241. The engine has been sitting on the workbench since I pulled it and I think it's finally time to start working on it. The engine is not the only piece to the puzzle as I believe it's time for a new driveshaft and couplings as well, but that may still be a ways out. The tractor is also going to need a pair of new front tires as well, as the originals are beyond their prime and have now begun to separate at the tread lines.

So tonight began disassembly and inspection. I apparently had the front bearing plate off at some point previously as the bolts were only finger tight. I was first able to confirm that the engine is indeed sleeved. There is a very clear ridge where the sleeve is compared to the block material. I could also see what was clearly a relatively new connecting rod.
IMG_20230706_210633.jpgIMG_20230706_210652.jpg

Here's the top of the piston, maybe you can see the gap between it and the walls of the cylinder. I previously measured with a pair of pliers that the bore is .010" oversize and that this is a standard size piston incorrectly installed into it. Another thing, I noticed that the top of the piston does not actually reach the very top of the bore, as can be seen in the second picture. Is this how the engine is designed or is something else wrong here?
IMG_20230706_212033.jpgIMG_20230706_212053.jpg

A couple other things I noticed, you can just see a little bit of the new style governor, another sign this engine was indeed rebuilt. Also, here's finally a picture of my infamous drill bit points plunger which I mentioned elsewhere in this thread, it is indeed one end of a drill bit with just a little bit of the spiral remaining. Interesting, yes, but it did work. Lastly just a quick shot of the internals after removing the oil sump.
IMG_20230706_210734.jpgIMG_20230706_221943.jpgIMG_20230706_222700.jpg

[Cubcadet_107]

Then I set to work removing the piston and connecting rod as well as the crankshaft to inspect them all. This is what the bore looks like. It's a bit scratched up, which I believe was caused by the incorrect piston slapping around in the bore as well as the incorrect size rings. The piston is also scratched up, though no scratches on the piston or bore are deep. I took one ring from the piston and test fitted it in the bore, and the gap size is far larger than the .020" maximum recommended in the IH 1x6 1x7 series service manual.I did not have a large enough feeler gauge but the gap is at least .030" further confirming this piston and rings is the incorrect size.
IMG_20230706_224358.jpgIMG_20230706_224605.jpgIMG_20230706_232058.jpg

Here's the crankshaft journal, it looks fine, however based on what my neighbor told me and what else I found this crank is ground .020" under which is smaller than the maximum connecting rod undersize you can get.
IMG_20230706_224525.jpgIMG_20230706_224535.jpg

So here's how he said they fixed it, they took a .010" undersize rod, machined a little bit of material off the cap, then milled it back to round to make the rod fit. The milling marks can quite clearly be seen on the connecting rod and cap.
IMG_20230706_224652.jpgIMG_20230706_224708.jpg

Lastly, the oil pan sludge. Yes, this pan does have some rather metal-y sludge unfortunately. However my inspection has led me to conclude that this sludge is a mixture of normal break in wear (as this engine was barely run after its previous rebuild) as well as piston and bore material from all the scratches.
IMG_20230706_232757.jpg

The bore is okay, it can do with nothing more than a light hone to get crosshatching back. It is not out of round. The piston and rings will obviously be replaced with a correct .010" oversize set. As for the connecting rod and crankshaft, based on the conditions of them I know I have the option to reuse them. However I do not really like the whole idea of the custom undersize rod and would like to replace it. Replacing it though means also finding a replacement crankshaft which may also need machining if I can't find one within standard spec. I have a lot of work ahead of me to get this engine back to running condition, and it's definitely not going to happen fast, but I am glad to get started on it after so long.

[ol'George]

Originally Posted by Cubcadet_107

After almost 2 years, it is time for me to bring this thread back. The k301, as worn as it is, has been doing alright in the 107 and I have been in no rush to do the work to the k241. The engine has been sitting on the workbench since I pulled it and I think it's finally time to start working on it. The engine is not the only piece to the puzzle as I believe it's time for a new driveshaft and couplings as well, but that may still be a ways out. The tractor is also going to need a pair of new front tires as well, as the originals are beyond their prime and have now begun to separate at the tread lines.

So tonight began disassembly and inspection. I apparently had the front bearing plate off at some point previously as the bolts were only finger tight. I was first able to confirm that the engine is indeed sleeved. There is a very clear ridge where the sleeve is compared to the block material. I could also see what was clearly a relatively new connecting rod.
Attachment 113117Attachment 113118

Here's the top of the piston, maybe you can see the gap between it and the walls of the cylinder. I previously measured with a pair of pliers that the bore is .010" oversize and that this is a standard size piston incorrectly installed into it. Another thing, I noticed that the top of the piston does not actually reach the very top of the bore, as can be seen in the second picture. Is this how the engine is designed or is something else wrong here?
Attachment 113120Attachment 113121

A couple other things I noticed, you can just see a little bit of the new style governor, another sign this engine was indeed rebuilt. Also, here's finally a picture of my infamous drill bit points plunger which I mentioned elsewhere in this thread, it is indeed one end of a drill bit with just a little bit of the spiral remaining. Interesting, yes, but it did work. Lastly just a quick shot of the internals after removing the oil sump.
Attachment 113119Attachment 113122Attachment 113123

Me hopes you didn't measure the bore with a pair of pliers
prolly the spill chick feature, but it gave me a needed laugh.

As most know when a bore is beyond available piston oversize's it can be bored and a sleeve installed to return it to standard bore.
After the sleeve is installed, it is bored to near finished size, then honed to the finish size.
Me thinks an awshit occurred with the finished bore/hone process.
We all make mistookes.
Sooo carefully measure with your precision telescoping gauge & mike, or dial bore gauge because you really don't know just what you have.
Is it really .010 over? or more or less as a mistake was made during the finished sizeing.
No need to make things worse by assumptions.

I think there are several places to get undersize rods,one is "I save tractors" and another is "bakt4kids" on evil pay.

The resizing of rods, as was done, is usually done to restore to original size
of the rods inside diameter, then use an undersize bearing insert to match the crank diameter.
But in this case these rods normally do not use an insert as we know.
All that said:
I'm thinking the process of milling the rod, then boring undersize to fit the crank is where you lost the piston height.

If the crank is .020 under, you loose .010 there.
and we can only guess how much was milled off the rod in essence shortening it also.

Sorry if you already figured this out or I have lost you.

The cylinder/piston scratches are from a poor job cleaning the block before assembly.

[Ambush]

ole-George nailed it all.

If the bore is .010" over on a standard piston then your measured ring gap will be more like .050". I'd also guess someone got overzealous with the hone AFTER ordering the standard piston. I'd suggest buying a .010" over piston/ring set then carefully and properly hone the bore to fit. You might have to take it to an engine shop for that.

Resizing con rods that way was a pretty common practice at one time and if done properly was a good fix. Labour used to be cheaper than parts. I've done it myself after a crank polish to gain back a few thou.

Probably by the time you mill the head and block, you'll gain back most of the con rod length. Your stroke is still the same. Besides, what you gain in a having a proper piston fit should keep you happy enough with the performance.

[West Valley G]

Excellent update pics and such. Amazing what a guy can learn while he
is just sitting here eating his lunch. Thanks for taking us along 107

Ken

[Cubcadet_107]

Definitely did NOT measure the bore with a pair of pliers. It was late last night and I don't really know what I was saying. That was supposed to be calipers. Not sure why my mind went sideways

It was a pretty consistent .010" oversize when I measured it back a year ago or so. but yeah that was a while back. I think about making a small mistake in the machining process like that but then taking a look at the fit of the piston in the bore it really seems like a lot more slop than a slight mistake. But I guess I don't know for sure.

As for the rod and crankshaft, I feel safer with my abilities going with a new crankshaft and rod. Besides anything else I do not like the way the bolts are situated on that rod. I don't know what is going on with it in the slightest, the bolts go all the way through and out the other side where there were two nuts that appeared to have loctite on them. You can't tighten them any once they are in there, as they sit flush against the rod. It seems like a really difficult setup to tighten properly once the rod is in there. I am not sure if maybe the bolts should have been installed the other way around and then the nuts tightened on them? I cannot tell just by looking at it but I don't really want to put it back together with that.

Also as for the rings my thoughts could be way off. As I said I don't have a feeler large enough to actually get the correct measurement of that gap. All I can say for certain is it is much larger than the .020" maximum.

[ironman]

Originally Posted by Cubcadet_107

Also as for the rings my thoughts could be way off. As I said I don't have a feeler large enough to actually get the correct measurement of that gap. All I can say for certain is it is much larger than the .020" maximum.

Just for a rough guess....
.020 might be the largest on the tool but .020 combined with .019 on the same tool = .039
.018 and .015 = .033
etc.
etc.

[Cubcadet_107]

Good idea, I just tried it. Actual ring gap is around .040"

[jbrewer]

(yes, this is an old thread but you did such a good job with the pictures and description!)



Looks like you might get away cheap with a rod/piston kit from the usual places, along with a very light hone of the bore.



I wouldn't be worried too much about the piston deck height. Once you get the right size piston and rings in there, I doubt there's any noticeable difference in performance. As George said, sleeving a block (especially on a low compression, low performance engine like these Kohlers) is a good fix if the shop did a good job.



Looks like someone rebuilt the engine with the wrong parts, was disappointed with the results, and sold it off. The McGuyver work with the drill bit was inspired.