Key-way fix - anyone try it?
 

The keyway on the K301 I'm working on rebuilding is pretty bad, the key slides about half a key width to the side. In looking up alternatives to a new crank, I came across some products that are supposed to fix bad key-ways. One is a Loctite product and the other is Belzona. I found videos for each and attached them below. I've heard of other guys using JB Weld as well. Has anyone used this or is it just a waste of time and needs to be fixed properly?

Loctite- https://www.youtube.com/watch?v=LLSLtr0ECbc
Belzona - https://www.youtube.com/watch?v=BOt5V5TZefI

I moved this to the Kohler section. Just my 2 cents, if you are rebuilding it just have a new key way machined into the crank 180 degrees from the bad one. :beerchug:

That's the solution. :ThumbsUp:

Belzona is some really good stuff--it ain't JB Weld, that's for sure. However, you get what you pay for and you will pay dearly for it. We had to use it on a project at work some years back where we actually had to mill it afterwards. It worked pretty good.
The Loctite looks promising but by the time you order the 3 different things you need, it's going to be pricey also.

Any machine shop should be able to cut you a new key in 30 minutes unless its a woodruff---still doesn't take very long but he may not have the correct cutter. Do yourself a favor and see if you can just get a new key cut on the shaft for a reasonable price. It will be better than a patched keyway. Those repair products are generally used to buy time until the machine can be taken out of service for a long time to replace the shaft. Likewise most industrial stuff is custom (unless we are talking about electric motors or gearboxes) and the shaft would have to be made.

I gotta agree with Mike, most "fixes" are temporary at best.

Have the shop cut a new keyway for you, surely you aren't the first one to show them a bad keyway in a crank shaft.

Sounds like a job for Mr. PA. First name Jeff In

If it were in a used engine and you didn't want to take it apart I would say try it. what have you got to lose? I've used JB weld to repair a few. but since you have it apart I'd just get a new keyway cut in it

Sam Mac - Thanks for moving the post, I wasn't sure where to put it since keyways are found all over the machine and not just the engine.

If something is worth doing, it's worth doing right so I'll take your gentlemen's' advice and see about get a new keyway cut. There aren't any local machine shops here in BFE Nebraska but I think I know of one a few hours away. Any idea on what a fair price for simple keyway would be?

depends if you know a machinist:biggrin2:

maybe 20-50 bucks

I would get in touch with member JeffinPA. You could box up the crank and send it to him. Before you do that I'd have it check to see if it needs to be ground.

Get a quote before you let a shop do the work. Our shop does basically nothing for the general public. It would be $75 min. An old school shop, retiree with a mill in his garage, possibly even an automotive machine shop would be who I would look for. Even a GOOD maintenance man at a factory--probably has acess to a milling machine.

I prefer to mill a new keyway 90* from old one, not *180.
---------Done a few over the years.
Or, you could mill a wider keyway in the old location, and make a step key, if it is not wallowed too bad. :beerchug:

90 is what I do also. :beerchug:

Your reasoning is....? Does the shaft get a flat spot or something 180 from the key way and can affect the new key? I'm just curious is all.

Bill

Yes I have done about 4 keyway repairs to date. I weld up the wallowed out area very carefully with a mig welder and then take the crank and a 12 pack of beer to the machine shop dept. Couple days later I have a very nice reworkrd crankshaft.:beerchug:

You have less of a chance of any problems @ *90.
if another keyway is cut @ 180 then you have a chance of problems later on.
In an industrial situation, we had to look @ all angles so to speak,as
our machines/equipment ran 27-7, 365.
Downtime ran in the thousands of dollars a minute.
anytime you can prevent a problem or plan downtime, it was a plus.

A shaft cut @ *90 will not tend to become undersize/wallow like it will @ *180
Just like setscrews, they are set @*90.:beerchug:

Running those machines 27-7 is hard on them:)

Send me pictures, pretty sure I can do it.

Jeff

Jeff in PA - I'm trying to get my students to get it tore down before Christmas break so that I can get it checked and order an overhaul kit so it will be here before school resumes in January. I'll be able to get a picture of the keyway this afternoon but probably won't have the crank completely out till the end of the week to know if it needs to be ground as well.

Finally got some picture of the shaft. It was a real pain to get the clutch basket off because the key was deformed and wouldn't allow it to slide. It was about every time you started it that you had to put the starter belt on because the clutch basket wouldn't stay tight without wobbling.

I noticed that the set screw had worn the side of the shaft at 90 degrees cw. Would it probably be best to get the new keyway cut at 90 ccw from the old? And I know where the vbelt runs on the basket has some issues with being pinched in, would it be a good idea to just get a new one of them too?
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I would replace the basket pulley with a new one, if it has any wear it will wobble and eat the new key way.

It might be an illusion, but I think that crank has pretty bad wear on it.
Is that metal that is pushed up on the tapered area?(right next to the biggest rust spot)

Youch!
I'm with Terry. That crank looks pretty worse for the wear!

You might be able to have it welded up and machined down.... maybe. And it might break after some use too. Can't weld the rod journals because they will break, but you might get away with having that end done. I'd suggest a machine shop, but a crank shop would be better. They will weld it with a submerged arc welder on a lathe, so it will be done evenly. Only other choice would be to turn it down and run a thin sleeve.

No more than crankshafts are, I'd probably just replace it.

The previous owner let the ware button go too long and the fingers eventually caught on the pto lever and gutted the pto. He then continued to use the tractor for mowing but the 48" deck was always live. I'm no rocket scientist but I think that has a huge part in why it looks that bad.

I'm going to get the head off and have the bore checked out. If it needs bored and a lot more work I might part it out and just get a new motor. I only wanted to be into this motor for around $200. If the piston is too egg shaped I'll probably just look for a replacement.

Thrust head on the piston measures 3.340 and should be 3.363. Is that probably just from wear? Still need to get it to a shop with the correct tools to check bore but from the look of the piston, I'm thinking the machining may be more than I want to spend on the block and if that's the case, no need to get the key cut.

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The piston shows many hours wear, the bore will most surely need bored/honed oversize with of course, oversize piston.
There is a Seller on ebay that several here have successfully used, who sells a complete kit for less than $125
Rod/piston/rings/gaskets etc. all you need.
You would need to purchase a good used crank, hopefully not needing turned,and pay for cylinder machining.
You will go over a $200 budget, but will have a new engine for all practical purposes.
I'd do it myself, but to each his own.

That crank has seen better days. I will respectfully decline to machine a new keyway as it would NOT be a good value with that crank.

I don't mind helping folks out but don't want to waste anyone's hard earned money.

Jeff

That's something you don't see everyday, someone more concerned about the customer than there wallet.:beerchug:

Jeff is a good honest guy.
If it were my crankshaft, I doubt it would be worth my time to put it in my B'port
mill , as when I got done the keyway would be as new, but the diameter of the crank in that area is worn so even a new clutch basket would still be sloppy and
the "repair" would be short lived.
Now we have all did things to get us by, till a replacement or other arrangements were made.
Planting/harvest or haying time, some unorthodox repairs are always made.

Given the cost and availability of that crank, spray welding or other methods of repair are not cost effective.
It could be cut undersize as others mentioned, and a tight fit bushing made, then a captive keyway milled restoring it, in an event that is was something,
that was unobtainable or a very collectable/valuable instance.
Sorry for the long comment.

Thanks for all the replies and advice.

I'm going to get the block to a garage in town with the proper tools to tell me if its salvageable and estimate how much it would be to bore it out.

A member of the site pm'd me and offered to make a deal on a crank and overhaul kit.

I'm not going to mess with putting money into something that won't last so if the block is salvageable for a reasonable cost, I'll just replace the crank.

To fix, or not to fix , that is the question .
 

So..., what's the verdict? Inquiring minds want to know. I'm with ol' George , I'd
get a crank, rebuild kit and it would be practically new.

Chris

Sorry, been a little while since I checked on this post. I decided to button the motor back up and keep it under the bench until I have enough money saved to fix it properly. Might just use the engine as a parts motor or see if I can get a better crank sometime down the road. IDK yet.

I ran and add on craigslist and found a guy in Council Bluffs that pulls and had a k241 out of a 104 that he didn't want. Made me a pretty good deal for the motor with accessories on it. And since it's going in a 100 it would be more true to the original. Been having my students work on taking it apart to overhaul it instead now. The new motor had a broken head bolt so I've been able to teach them more about fixing an engine than I originally would have been able to with the K301.