K301 Block - Use it, or Scrap it?

[Rhoderman]

Today was looking like a good day. I pulled the K301AS from my CC122. Everything was going quite well until I got to this:



It looks like this engine has thrown a rod somewhere in the past. There were no chunks or pieces found, so they cleaned it up fairly well.

Can I use this block, or should I start looking for a new one? I'd hoped to do a simple full rebuild with a new piston and rod, but now I'm not so sure. The piston had an "A" on top - is that factory size, not overbored yet? The piston is pretty pathetic, it has what looks like carbon scrapes above the first compression ring. The oil ring and the 2nd compression ring had the gaps lined up, which probably wasn't good. Probably didn't matter though, this thing was pumping oil like mad.

Please, someone, tell me that you've seen worse and had a successful rebuild? Please?

Man, this sucks...

Thanks,

Jim

[zekepiks]

Rhoderman,
I have rebuilt two different blocks that where broke in the same place ,actually one had a bigger chunk missing and they both turned out fine, The piece that was broke off is below the skirt of the piston. If it was mine I wouldn't worry about it at all Skip (zekepiks)

[cwmcbee]

If it was mine I would also rebuild it.Some car engines are notched more than that when a stroker kit is used.

[clint]

I think I read somewhere that it was caused by the bottom stroke of the piston, I forget the exact reasoning behind this.

As said above some car engines are done this way on purpose, and not only ones that have been stroked, some OEM that are being rebuilt are done this way to prevent "piston slap" I always thought piston slap was the piston hitting the head, however I learned that it was the piston hitting the area that broke off you have pictured.

Don't worry about it, rebuild it, I would however make sure no raised edge around the broken off piece.

[Merk]

I had one like that. That motor was sleeved.

First thing I would check is the bore diameter as shown in section 10 thru 12 in a Kohler service manual. That could help to make your deside what to do with the block. That could be a good way to get the motor back to the orginal bore.

[Rhoderman]

Thanks all. I feel relieved that it should be usable.

Merk - did you mean it was sleeved before or after the chunk blew out the side?

I'm thinking this engine is on the original piston since it had an "A" on the piston face. Is that a valid statement? I was hoping to bore it +0.030 and never worry about it for 20 years +/-. Now you got me wondering if I should sleeve it, or bore it, hone it, and run it.

I don't have any bore mics, so I was planning on having the machine shop tell me how much it will take to clean it up, and buy a rebuild kit accordingly. Same for the rod journal and con-rod.

Jim

[clint]

Rhoderman

Or Jim, whichever you like, I'm one of those odd ball out kinda guys. I don't like bored motors of any kind really, much less the single cylinder Kohler K series. The engine is already out of balance, and it just seems it will worsen the effect with an over-bored piston. I don't have any problem with work to the crankshaft, bored out with inserts, oversize etc, it's the piston/bore I think should stay the same. If you have the money, or it's not to expensive I would have it sleeved... That being said I think having a block sleeved is going to cost you, so in that respect I will go with Merk's opinion (from what I got from his post) If the block needs bored out I would look for another block then. If the block is in good shape, I would just replace what is needed/worn etc. That's just my stand on what to do, if you are in a area that you can get access to a machine shop, or the services cheap, then by all means you make the choice. The missing chunk in the block however is only cosmetic, but you have to keep everything in mind when you go to sink a large sum of money into it.

[Merk]

Last block I had sleeved cost me around $80 to $90. One block was to it's max bore size and another block was like the one in Rhoderman's orginal post.

Everyone motor that I rebuild has been bored. It didn't affect the balance on any of the motors.