Engine Rebuild - Lessons Learned

[MaineDad 87]

As some of you know, I tore into my K301 on the 1977 C-120. Below are the details of the process. I hope this thread will help other people do it right and save money;

My first attempt was to just install a new piston, connecting rod, valves, and rings, a top-end rebuild if you will. I thought the cylinder bore was within "Standard" specs because I measured the cylinder bore myself with calipers I bought at Sears, and honed it with a flex hone I purchased from eBay - total cost including new flex hone and measuring tools was $250. Well, it did not work, I was still getting a lot of smoke, so I proceeded to do my first complete engine tear-down. Nervous!

I took the engine down to the block. Unfortunately, I had to hack saw the drive pulley off! It did not respond to a torch or the puller. Once it was all apart, I took the block to a machine shop where, with their precision measuring tools, it was determined that the cylinder was not within "Standard" bore specs and needed to be bored .010 over. It was also determined, with more of their precision measuring tools, that the crankshaft needed to be mic'd .010 under. Of course this meant I needed to purchase a new piston, rings, and matching connecting rod. It also meant that I would incur machine shop costs for the boring, honing, re-cutting of the valve seats and milling of the cylinder head to make sure it was flat . One machine shop worked on the block, another machine shop did the crank journal because the first shop did not have the tools to mic the crank. The total for the new parts, including a new gasket/seal kit, new drive pulley, and machine shop costs equaled $460. However, I decided not to replace the valve guides while the block was at the machine shop because they looked OK, a little worn, but acceptable according to the first machine shop. WRONG!

I put it all back together again using the Kohler Service Manual. Not that hard except getting the shims to stay in place while you install the cam! Everything was within specs and ready to go! The engine ran fine at first, but was still smoking and skipping. Dang! So I took the head off and noticed a considerable amount of oil around the intake valve. I then checked the valve/breather assembly and it was full of black, sooty oil. Drained the fresh oil and it too was all black. Big SIGH - I had to again do a complete tear down of the engine.

So I ordered new valve guides and took the block to the second machine shop who did the crank for me. He quickly confirmed that both valve guides were worn and needed to be replaced. Of course when you replace the valve guides, you also need to re-cut the valve seats so the valves run true in those new valve guides. Cost to de-glaze the cylinder, remove and install new valve guides, re-cut the valve seats and buy new valve guides was about $80. Another $30 for another set of gaskets and seals, totaling an additional $110 or so.

So I'm $800 plus into this new rebuilt K301 - I am not happy about the costs, and neither was my wonderful wife - But I have learned a lot. Hopefully my write-up on RS will help someone else not make the same mistakes I made. The lessons I learned were;

Professionals have much better and accurate measuring tools

Find a machine shop that has worked on these old Kohlers before

While you are inside the engine don't forget about the valve guides

Always follow the Service Manual step by step

And be patient

I actually did enjoy the rebuild process and look forward to doing another rebuild. It really was not that difficult. I mowed the lawn tonight for the second time since the final rebuild and boy does it go sooooooo much better through the tall grass! I can't wait to see how it does with the snow

I hope I helped someone with this long write-up!

[rmaynard 16,333]

Hindsight is always 20/20.

And most of us don't have bottomless pockets.

[MaineDad 87]

Bob,

I don't have "Bottomless pockets" which is one reason why I wrote this up. Why?

[jbumgarner 12]

From a newbie to RS and Kohler engines I appreciate your write up. Thanks and I hope you have many good years out of the new engine. :thumbs2:

[rmaynard 16,333]

My comment was based also on the way that I did my rebuild. Because I don't have an unlimited amount of money to spend on my tractors, I did only what I thought was necessary. I didn't think my guides were too bad either. Therefore, I find myself in the same boat as you, needing new valve guides. It would have been a lot less expensive to spend more money on the initial rebuild, than to have to take it all apart and do it again.

Kind of a take-off on my signature: "if you don't have the money to do it right the first time, where are you going to find more money to do it over?"

I hope you didn't think I was implying that you had bottomless pockets.

[Martin 2,133]

As some of you know, I tore into my K301 on the 1977 C-120. Below are the details of the process. I hope this thread will help other people do it right and save money;

My first attempt was to just install a new piston, connecting rod, valves, and rings, a top-end rebuild if you will. I thought the cylinder bore was within "Standard" specs because I measured the cylinder bore myself with calipers I bought at Sears, and honed it with a flex hone I purchased from eBay - total cost including new flex hone and measuring tools was $250. Well, it did not work, I was still getting a lot of smoke, so I proceeded to do my first complete engine tear-down. Nervous!

I took the engine down to the block. Unfortunately, I had to hack saw the drive pulley off! It did not respond to a torch or the puller. Once it was all apart, I took the block to a machine shop where, with their precision measuring tools, it was determined that the cylinder was not within "Standard" bore specs and needed to be bored .010 over. It was also determined, with more of their precision measuring tools, that the crankshaft needed to be mic'd .010 under. Of course this meant I needed to purchase a new piston, rings, and matching connecting rod. It also meant that I would incur machine shop costs for the boring, honing, re-cutting of the valve seats and milling of the cylinder head to make sure it was flat . One machine shop worked on the block, another machine shop did the crank journal because the first shop did not have the tools to mic the crank. The total for the new parts, including a new gasket/seal kit, new drive pulley, and machine shop costs equaled $460. However, I decided not to replace the valve guides while the block was at the machine shop because they looked OK, a little worn, but acceptable according to the first machine shop. WRONG!

I put it all back together again using the Kohler Service Manual. Not that hard except getting the shims to stay in place while you install the cam! Everything was within specs and ready to go! The engine ran fine at first, but was still smoking and skipping. Dang! So I took the head off and noticed a considerable amount of oil around the intake valve. I then checked the valve/breather assembly and it was full of black, sooty oil. Drained the fresh oil and it too was all black. Big SIGH - I had to again do a complete tear down of the engine.

So I ordered new valve guides and took the block to the second machine shop who did the crank for me. He quickly confirmed that both valve guides were worn and needed to be replaced. Of course when you replace the valve guides, you also need to re-cut the valve seats so the valves run true in those new valve guides. Cost to de-glaze the cylinder, remove and install new valve guides, re-cut the valve seats and buy new valve guides was about $80. Another $30 for another set of gaskets and seals, totaling an additional $110 or so.

So I'm $800 plus into this new rebuilt K301 - I am not happy about the costs, and neither was my wonderful wife - But I have learned a lot. Hopefully my write-up on RS will help someone else not make the same mistakes I made. The lessons I learned were;

Professionals have much better and accurate measuring tools

Find a machine shop that has worked on these old Kohlers before

While you are inside the engine don't forget about the valve guides

Always follow the Service Manual step by step

And be patient

I actually did enjoy the rebuild process and look forward to doing another rebuild. It really was not that difficult. I mowed the lawn tonight for the second time since the final rebuild and boy does it go sooooooo much better through the tall grass! I can't wait to see how it does with the snow

I hope I helped someone with this long write-up!

im sure many of us who read this will have something to think about. we all like to try and do things on a budget, sometimes that means cutting some corners, sometimes it works out ok but most times it ends up costing much more.

i still try and save a buck here and there. human nature. it will work out sometimes and then sometimes it wont.....

i dont like it when things work out differently than planned, especially when it costs much more than it should have. the key is to learn from that instance and not repeat it again, hopefully!!!!!

i enjoy learning from mistakes, it helps.....and sometimes it hurts.......

thank you for sharing your experience.

i find it hard sometimes to come clean about something that ended up wasting time and money. id much rather not talk about it........... :banghead:

[smoreau 658]

This happens more then most people will admit. I did the same on my 875 and it smokes more now then it did before the repair this tractor will never be worked again and will be just a show tractor and joy ride here and there. Some day I will make it right, but it's running good with anti-bug smoke out of the stack.

[Martin 2,133]

This happens more then most people will admit. I did the same on my 875 and it smokes more now then it did before the repair :thumbs2:

[sgtsampay 117]

Sry to hear about all of your troubles there. I have also done my fair share of cutting corners on engine rebuilds. My first twin briggs rebuild I thought I could just put some rings and new pistons in it and then lap the values and call it good. Well, I should have done it proper and bored the engine, along with get everything miced and such. Because of my "cutting corners" the engine only lasted about 10 hours and then the right cylinder stopped fired and it starting using lots of oil. I was already about $300 into the engine and it only lasted 10 hours! I was so upset, that I junked the engine.

Now, based on this experience and the trouble my neighbor had doing the same thing to a onan twin, I was really upset when I learned that my old Briggs 16Hp off my GT-1600 was in need of a rebuild. So, I added the cost of it being bored, miced and such from the shop then all new pistons/rings. I also didn't take into account for new valves and valve guids but i figured it would be the same cost if not cheaper to get a whole new engine. That was the main reason for me to "try" out the diesel since it was $650 shipped to my door.

Moral of the story, if you don't mined using a different engine than the orginal, then looking into getting a different engine may be a good idea.

Sry for hyjacking the thread...

Hey Micah, I bet that thing will blow some serious snow now! Also, how tall was the grass you cut with it? Just curious..

[JimD 3,347]

Thanks for sharing your story so many can learn from it.

[Coadster32 793]

I was so upset, that I junked the engine.

Understandable indeed.

Sorry about the cost Mica, but glad to hear you persevered thru and got it finished right. Thanks for posting up this lesson, and hope others hear it as well. :thumbs2:

[JC 1965 1,532]

:banghead: Micah, Thanks for sharing this info with us. I am seriously thinking about doing my first engine overhaul this winter on an old K 301. I have a lot of back problems so I'll have to wait and see if I'm up to the challenge Thanks to your post, I know what I should be done to get the best results. Again THANKS!! :thumbs2:

[JC 1965 1,532]

:banghead: Micah, I forgot to ask in the above post, Did you use kohler parts or after market parts? Some folks say the after market parts are good and some say they don't like them. So I was just wondering. I'm just Trying to gather all the info that I can. :thumbs2:

[rmaynard 16,333]

With lessons learned, I am about to embark on a K301S rebuild over the winter. Since there is no rush on this one, I WILL do it right this time. As Micah said, with one part at one shop and another part at another shop, there was no coordination. I have found a machine shop that specializes in Kohler's. He is not the cheapest guy in town, but his results are beyond reproach. Allowing him to do all the internals assure me that if there is a problem, I don't have to fight between two or three shops over who did what wrong.

I may have to put more money into this engine, but it will only be rebuilt ONCE. Then I will put it on one of my B-100's and have the first B-120 that I know of. :thumbs2:

[MaineDad 87]

Bob - Sorry but I did think you thought I had "Bottomless Pockets." Thanks for clarifying your statement. Good luck with your B-120!

Jerry - Yes I did use the Stens rebuild kits. I read a lot on Brian Miller's pulling site and he has had no problems. If I did use OEM parts, it would have cost a lot more :thumbs2:

[MaineDad 87]

Bobby - The grass was about 6 to 8 inches tall and very thick especially over the leach field. I used to have to use low 2 to get through it. Now high 1 goes right through it!

[Coadster32 793]

Allowing him to do all the internals assure me that if there is a problem, I don't have to fight between two or three shops over who did what wrong.

Priceless approach. :thumbs2:

[dgoyette 12]

Great write up Micah...very good read for anyone considering engine work options.

[sgtsampay 117]

Bobby - The grass was about 6 to 8 inches tall and very thick especially over the leach field. I used to have to use low 2 to get through it. Now high 1 goes right through it!

Wow! Thats some serious grass your cutting then. Wow, I bet that Kohler had a nice chug to it.

I can't wait to see this year's video's of it slinging some snow.

[condo630 7]

With lessons learned, I am about to embark on a K301S rebuild over the winter. Since there is no rush on this one, I WILL do it right this time. As Micah said, with one part at one shop and another part at another shop, there was no coordination. I have found a machine shop that specializes in Kohler's. He is not the cheapest guy in town, but his results are beyond reproach. Allowing him to do all the internals assure me that if there is a problem, I don't have to fight between two or three shops over who did what wrong.

I may have to put more money into this engine, but it will only be rebuilt ONCE. Then I will put it on one of my B-100's and have the first B-120 that I know of.

A B120...that's cool. I was thinking about building a Raider 16, might still do it someday.

Glad to hear all this, might have some rebuilding to do eventually.

[AMC RULES 37,196]

So, approximately how much should it have cost to do the first time having incurred none of these problems?

[C-85 753]

Hi All,

I rebuilt my C-85 and C-105 Kohler engines and used a machine shop for the measuring and machining work. This worked well, but I still had a hard time doing them. I have a Kohler service manual that I found to be very frustrating to use. I found the pictures in the manaul has to be very poor. Of course they are black and white pictures, but some of them are to dark to get any real detail that is useable. A lot more pictures in the manual would have also been a more useful! And then the info was kind of weak in several different areas. I wouldn't try rebuilding a Kohler engine as a beginner by trying to use their manual!

I wonder how many other members have struggled with the Kohler manual?

C-85

[rmaynard 16,333]

I wonder how many other members have struggled with the Kohler manual?

I found the Kohler manual to be quite useful. I didn't have any trouble following the correct sequence of disassembly or reassembly. The pictures in mine were fairly clear. But by not thoroughly reading ahead, I installed the valve springs upside down and had to go back and correct them.

[SAM58 30]

I wonder how many other members have struggled with the Kohler manual?

I found the Kohler manual to be quite useful. I didn't have any trouble following the correct sequence of disassembly or reassembly. The pictures in mine were fairly clear. But by not thoroughly reading ahead, I installed the valve springs upside down and had to go back and correct them.

HUMANS....

SEEMS LIKE THEY ALL MAKE MISTAKES.

THOSE ARE THE LESSONS THAT STICK! :thumbs2:

[MaineDad 87]

So, approximately how much should it have cost to do the first time having incurred none of these problems?

Craig,

It probably would have cost $400 to $500...