K-181 Piston or Valve Slap!!???

[Easton Rich 584]

I just finished my B-80 and there is now slapping/knocking sound coming from the upper part of the cylinder. Just what need right when I finish it. Any help or advice is greatly appreciated!

[oliver2-44 10,520]

What was done to the engine?

Hone and rering?

Bored oversized?

Crank ground and undersize rod?

Valve guides replaced.

Valves clearance set by grinding stems?

Edited May 31 by oliver2-44

[Easton Rich 584]

Nope. Completely stock. Never touched it internally. It ran fine and I didn’t wanna change that.

[ri702bill 9,160]

Time to invest in a head gasket. Remove the head, noting the overall condition of the gasket seal - is it completely sealed?? Time to measure the cylinder bore and write down the results. this requires telescopeing bore gages and a good dial caliper. with the piston at the bottom of its stroke, measure the bore in 6 places: top(where the rings hit, not the very top), middle, and bottom at 90 degrees. That would be parallel and perpendicular to the crank ends. Compare readings. Compare both the bore size and deviations to the allowable limits in the Kohler manual.

If ir looks questionable, time to remove the piston to measure it the same way.  The piston wears on the thrust side - if excessively worn, that causes the slapping noise as it wiggles its way up & down....

[kpinnc 14,143]

I gotta do the same on my son's Ranger. It has developed a "one per rev" knock from outta nowhere. Ran like a top before...

[953 nut 58,995]

Get out the timing light or do static timing on the engine, it could be ignition timing is causing the knock.

[Easton Rich 584]

17 hours ago, kpinnc said:

I gotta do the same on my son's Ranger. It has developed a "one per rev" knock from outta nowhere. Ran like a top before...

Welp at least I’m not in this alone

[Easton Rich 584]

I’ll check that before i tear it down

13 hours ago, 953 nut said:

Get out the timing light or do static timing on the engine, it could be ignition timing is causing the knock.

 

[clueless 3,165]

I'm confused, you said it ran fine but now it's not, what was done prior to the noise?

[RED-Z06 2,531]

Was the piston put back in the same orientation it came out?

[Easton Rich 584]

10 hours ago, clueless said:

I'm confused, you said it ran fine but now it's not, what was done prior to the noise?

Nothing 

[Easton Rich 584]

It’s a Kohler replacement short block

[RED-Z06 2,531]

So the engine was not disassembled during the refresh?  Was the sheetmetal removed? The head? Carb?

[Easton Rich 584]

17 hours ago, RED-Z06 said:

So the engine was not disassembled during the refresh?  Was the sheetmetal removed? The head? Carb?

Nope. I removed the carb, fuel pump and sheet metal, that’s all. It’s very strange. I’ve checked oil, I just changed it a week ago.

[RED-Z06 2,531]

1 minute ago, Easton Rich said:

Nope. I removed the carb, fuel pump and sheet metal, that’s all. It’s very strange. I’ve checked oil, I just changed it a week ago.

Sheetmetal bolt rubbing the flywheel?  Maybe something went down the intake and is firmly forged into the piston crown?

[Easton Rich 584]

I will definitely tear it down. If it is pretty badly damaged I will replace it with a 10-14hp Kohler. I will for sure keep this one and rebuild it, but I hope it doesn’t come to that😬

[squonk 43,208]

2 hours ago, RED-Z06 said:

Sheetmetal bolt rubbing the flywheel? 

Yes. Putting too long a bolt in the shroud can do this. 

[RED-Z06 2,531]

31 minutes ago, squonk said:

Yes. Putting too long a bolt in the shroud can do this. 

Been there done that.  On my K181 its tight quarters to the battery box so i put a 1/4-20 stud in that hole, slotted the cover.  The bolt was touching the flywheel and i spent an hour trying to figure out why it only did it with the shroud on

[Easton Rich 584]

I’ll check it out!!