K241 rebuild help needed
 

Hello all. I was given a 100 from a co-worker who had no idea the history of the tractor other than it threw a rod while trying to pull a trailer out of the mud. I have the machine apart replacing almost everything because it was left in the weeds for a couple of years and most things are rusted together. At any rate, one of my true loves is to rebuild engines so I was excited to get into the k241. This is my first cub cadet but figured the internals of the engine would be familiar. It was except for the method of removing the cam, haven't seen one that rides on a shaft like this. The block skirt isn't broken and the cam itself looks good, the piston is marked STD. I like to measure everything before going to the machine shop so measured the piston bore and crank journal in 6 places, 90 degrees from each other in triplicate. To cut to the chase, the largest bore is 3.2785, limit for std is 3.254. This appears to be 0.026 inch over std, is this possible for a std bore piston? At least one that "ran fine" until the rod broke? Also, the crank rod journal was found to be 1.4800 at the smallest. Std is 1.5000. This looks to be 0.020 inch under. Smallest rods 0.020 inch under? How did this not have a huge rod knock. Maybe it did and he didn't notice. Seems odd. Is the crank wasted? Anyone with some insight? Long winded but appreciate any input. Thank you.
Pete

Pete

It is so refreshing to have someone that knows what he is talking about. I'm sure the guys that know these engines much better than I do will chime in and work with you. Dvogtvpe, Merk and J-Mech have forgotten more about the older Kohler’s than I ever knew. I’m sure that they can help you.

Pete,

What measuring tool(s) did you use? Was it a mike-bore gage?

What parts were ruined?

Standard bore is 3.251. There was 4 different pistons for your K-241. They are STD-.010-.020-.030. They are mark with the numbers/letters I listed earlier.

You stated the bore was 3.2785. The biggest bore you can have is 3.281 (3.251 + .030). That leaves .0025 before bore is too big.
Your options are
1. You can try to have an automotive machine shop bore it
2. Different block
3. Install a sleeve in the block
4. I know some have bored and installed a piston from the next size bigger engine. I wouldn't do theat because it makes ther cylinder walls to thin.

If it was my block I would not do the first choice because there is barely enough materal to bore.....too easy to go oversize. The last block I had a sleeve installed cost around $90. I have three K321s that are sleeve with no problems. Rebuildable blocks can go for $25 to $75. I would find a different block if it came into my shop.

Depending on how the crank journal looks you may be able to reuse it as it is providing modifing a Kohler rod so it fits a .020 rod. The rod will need a bearing installed. Kohler rods are the only rods that can be fitted with and undersize rod bearing. You can weld the crank journal and have it machine to factory size. That will cost big dollars.

The measurements and last rebuild scare me. The previous builder didn't not know what they were doing. You would be better off with a different block and crank assembly. You could go with a K241 or K301 short block and reuse the carb, cylinder head and starter from your K241.

Let me know if you need some help....sounds like a fun project.

If the piston is marked STD, and the engine was running prior to throwing the rod, I suspect your measurements are off somehow. They don't make sense. Suggest you take it to a local machine shop and let them measure it as a double check. If your measurements are correct, the other advice from Merk is good.

I can't put my finger on it but while disassembling the engine something seemed "fishy". I figured if it hadn't been opened up all panels would be tough to separate but some came off easy. Like I said, rebuilding engines is fun for me, big and small engines so I had a feeling how this rebuild should go but it just never seemed right. I suspect someone has been in the engine who didn't know what they were doing. The top and bottom of the cylinder measures 2.2500, standard, but there isn't a sharp ridge at the top of the cylinder. I wonder if someone put in oversize rings on the original piston. Still doesn't make sense. I'll take the advice and remeasure everything. The block by the way is stamped k301 so I suspect I can go 0.030 over. I don't want to pay the machinist to measure to only find I posses junk parts. I'm measuring with a bore gauge and digital caliper. As a side note, I'll have to figure out how to post pictures, you'll get a kick out of the carbon stalactite blocking flow in the head. A true testament to the will of a flat head to continue running at all costs. If I didn't trust the guy who gave me the tractor I would be convinced the engine was put together with mismatched parts so the tractor "includes and engine" to sweeten the deal. Thanks for all the a advice.
Pete

I'd think if that piston was as loose as you say it would have hammered pretty bad and broken the skirt. but anything's possible

Sorry Merk, I keep misquoting standard bore size. 2.251. Thank you.
Pete

It's possible that it was worn that bad and still running. I just tore down a K301 and it had a standard piston. It had to be bored .030" to be true again.

I'd just take it to a machine shop. They'll tell you what you need.

large bore for a STD piston in a K241

A K301 can't measure 2.250.

I'm really confused...

The pto side of the block has k301 embossed there. It appears to be one of the k241 engines that is based on a k301 block. My understanding is that kohler didn't have enough k241 blocks for the run and had to use k301 blocks with a k241 bore. If true, the advantage is a thicker cylinder wall..
Pete

Not sure if this will turn out but trying to post two pictures of the afore mentioned head carbon buildup. I've never seen anything like it. You gotta love internal combustion engines! You can see where the intake charge kept a slot clean into the cylinder but not sure how the exhaust was removed. Not sure if the pictures turn out but the ridge of the carbon is almost even with the head mating surface. Thanks for the input and responses to my thread.
Pete

The second photo.
Pete

This is the statement that made some confused. I think you hit the wrong # key. Should be 3.251


As far as the carbon build-up, I'd say the motor was ran without an air filter, or some kind of a leak past the air filter. That would explain the excessive cylinder wear and the carbon.

Good point j-mech on both accounts. I'm using an ipad and I'm sure I messed up the "finguring".
Pete.

That explains it. Thanks.

Question. How do I know if my engine needs a short or long dipper rod? The big end of the rod that was in the engine is in pieces and not sure what it was. I think the oil pan is a shallow pan but not sure. I suspect this is what determines the length of the dipper. Is this true? Grabbing at straws here. Thanks
Pete

It's my understanding that the short dipper is for the flat pan (I have that on my 108) while the long dipper is for the engines with a pan with a sump.

The correct part number for your rod should be KH-47-067-11. This is the part number for the standard rod, cross it over (if you aren't using Kohler parts) to whatever brand you are using.

Thank you sawdustdad and j-mech. I don't want to get in trouble mentioning a company that sells parts but here goes. Pats small engine website has 47-067-13-s oem connecting rod for $28.90. Maybe that is the going rate but seems cheap for a kohler connecting rod. This states it is the long dipper so no good for me but maybe others. Again, not a sponsor so may have committed a sin and apologize if I did.
Pete

I have seen mention an 0.020 under connecting rod for a k241 but can not find one for sale. Kohler, stens, rotary or ....? Does anyone know who makes an 0.020 under rod? Thank you
Pete

http://www.ebay.com/itm/020-KOHLER-C...item1c3505504d

No idea if it's a good price or not. I have purchased items from the seller before without problem.

You really need to check this guy out.....
He has the rod you need. Call him. You DO NOT have to buy through E-Bay. He has a store.

http://stores.ebay.com/The-Mans-One-...=p4634.c0.m322

Same guy I posted ( just so the poster doesn't think he has two places to check out )

Sorry Jeff, we were posting at the same time!! LOL, I guess "great minds think alike"!!! :beerchug:

No problem, as long as he gets help with his K241, it's all good :beerchug:

Great info everyone. Thank you! Waiting to hear from the machine shop for what I need. Thought I would do a little research before hand.
Pete

Well the machinist called and the block is not cleaned up at 30 over. To sleeve will cost $150. Looking into putting a k301 piston into it. Has anyone here done that? I have seen mention of making a destroked k301 by putting a k241 crank and rod with k301 piston. The small end of the rod will have to be machined for the larger k301 pin. I wonder if the crank will have to be rebalanced. Does anyone know what a standard k301 piston, ring and pin weight? I see the forged m12 piston has a slipper skirt and narrower pin, I wonder if that weights close enough to not have to rebalance the crank. If I have to rebalance I suspect a sleeve would be cheaper. Does anyone know if there is a business/person in the Kansas City area that I might be able to get a block and/or rod from? Thanks for any input.
Pete

I've done the 10 to 12 bore on a 10. the wrist pin size is different so you have to address that. you could just get a 12 crank, rod and piston if you haven't purchased any parts. or used block. I get $40 + ship , someone else might have one cheaper.

Does your block have "K301" cast into the side? If so, there is enough meat to bore to 12 hp specs

The block does have k301 embossed on it. I guess the real question is rebalancing the crank. There is a good chance the crank is no good too, I haven't heard back on that yet. If so I suppose I could simply get a 301 crank if I have to buy one anyway. I have seen some abused small engines but this one takes the cake for sure. Looks to have never been opened and the bore is more than 30 over and the crank might be more than 20 under! And it ran that way! Not what I expected for sure.
Pete

You may want to check out Jon's rebuild service.

http://www.onlycubcadets.net/forum/s...137#post246137

I think I'd just sleeve it. Much less complicated solution, especially if your crank doesn't exceed .020 under-you can get a .020 under rod, then go back with STD piston, rings, etc.

Sawdust dad. That's is what I'm going to do. The crank is clean at 20 under so the machinist is going to sleeve the block. Does anyone know where to get a 20 under rod? I am having a hard time sourcing one. Thank you
Pete

Page three :biggrin2:

Thank you Jeff in PA. I must have over looked the link. Just ordered the rod. Hope to get the block back next week and get it back together soon thereafter.
Pete

On my K301 12hp Kohler, there is a small hole in the connecting rod. That must face the camshaft or bad things will happen.

http://img.photobucket.com/albums/v7...h_DCP_4987.jpg
click for larger pic

Noted. Thank you sir. Details details. Sure make a difference. I've been spending the last couple days preparing the garden for snap/snow peas and radishes. Good to get some soil under the nails again! Dog thinks it is fun to "help" too. Good times.
Pete

[QUOTE=Merk;242106]Pete,

Standard bore is 3.251. There was 4 different pistons for your K-241. They are STD-.010-.020-.030. They are mark with the numbers/letters I listed earlier.

Hi,
I asked this question in a new thread, I should have just reponded here first... You mentioned the marks on the piston that you 'listed earlier'? Sorry, but I must be blind but I can't find the earlier reference...
My 9 year old and I pulled apart our old K241, and the piston has an 'A' stamped on top. I haven't taken the block to the machinist yet for measurements, just wanted to arm myself with a little more info first. Could you please tell me what the 'A' indicates? 0.010 over?
Thanks!
Mark