Cracked head

john hall · #1 11-10-2018, 08:37 PM

Dad has a "100" assembled from more machines than a Johnny Cash Cadillac. It has a K181 Kohler in it. Been a long time since we ran it (governor issue). Carried it to the shop today and got it running. Noticed it appeared to be blowing by a head bolt, smut all over the head between the plug and the bolt.
Figured blown gasket, no big deal. Pulled the head off to clean it up. Wire brushed the carbon and found this. Dad couldn't ever recall seeing a Kohler head split. FWIW, the spark plug hole has been Heli-coiled, maybe some damage began there? Upon inspection, it appears I milled this head down at some point many years ago. Anyway, gonna be shopping for a used head. Need to look into a clutch disk as well.

Who else has seen a Kohler, or any other air cooled engine, split the head?

Jeff in Pa · #2 11-10-2018, 08:56 PM

I had a "other than Kohler" head gasket (without the fire ring) split on my K301 powered 125 let go and the hot exhaust did this fine number to it.

john hall · #3 11-14-2018, 04:39 PM

Well got another head on the way off ebay as well as a cheap gasket. Not sure if the gasket has a fire ring, won't matter no more than this thing will ever be ran. Where dad retired from was a Kohler, Wisconsin, Robbins, Briggs, and Onan dealership--he couldn't ever remember an air cooled engine cracking a head. The now retired go-to local engine machinist couldn't recall this issue either. Oh well, having the same troubles as everyone else is BORING.

R Bedell · #4 11-14-2018, 05:24 PM

Glad to hear you found another head.

cooperino · #5 11-14-2018, 06:50 PM

Does anyone have any idea what could have cause it? Did something cause a really rich condition or could an exhaust issue cause the excessive heat?

john hall · #6 11-14-2018, 07:06 PM

Quote:

Originally Posted by cooperino

Does anyone have any idea what could have cause it? Did something cause a really rich condition or could an exhaust issue cause the excessive heat?

Not really certain it was excess heat, nothing is distorted or melted just cracked all the way through. Honest, you could see fumes/vapors blowing out while cranking it up--appeared to be around the bolt. I figured no big deal, just a blown gasket. When I wire brushed off some of the carbon buildup I thought that's a weird place for a casting flash line--then I got it in better lighting and learned I had real troubles. I didn't clean the fin side but you can see the crack on that side as well. I'm guessing we put this lawnmower together around 92 or 93. The head shows where I milled it flat, don't know when I did it, but it was a LONG time ago.
Here's a pic of it after we painted it. It served as a butt buggy until dad bought a golfcart.

cooperino · #7 11-14-2018, 07:42 PM

Quote:

Originally Posted by john hall

Not really certain it was excess heat, nothing is distorted or melted just cracked all the way through. Honest, you could see fumes/vapors blowing out while cranking it up--appeared to be around the bolt. I figured no big deal, just a blown gasket. When I wire brushed off some of the carbon buildup I thought that's a weird place for a casting flash line--then I got it in better lighting and learned I had real troubles. I didn't clean the fin side but you can see the crack on that side as well. I'm guessing we put this lawnmower together around 92 or 93. The head shows where I milled it flat, don't know when I did it, but it was a LONG time ago.
Here's a pic of it after we painted it. It served as a butt buggy until dad bought a golfcart.

I am sorry. I confused yours with Jeffs.. Jeffs looks heat related.

dodge trucker · #8 11-14-2018, 08:02 PM

Not rich but excessively lean, it's like when you torch cut steel, you know when you squeeze the oxygen bar

Jeff in Pa · #9 11-14-2018, 09:02 PM

Quote:

Originally Posted by cooperino

I am sorry. I confused yours with Jeffs.. Jeffs looks heat related.

Mine was a cheap head gasket that failed between the layers. Hot gas etched the aluminum away literally within seconds. It changed sound, an aluminum "vapor" shot front and I shut it off.

The next day I had shoulder surgery and couldn't fix it. Luckily my neighbor Vic mowed for a couple months for me. He wouldn't accept gas or money for mowing but he would accept a case of beer

ol'George · #10 11-14-2018, 10:35 PM

Back a few years ago, (1977) I had a Minneapolis Moline 108 town & country
(Jacobson built) Garden tractor/mower with timed blades like an original CC.
I had a head crack on it but not through the plug hole.

Replaced it with a good head from a cub original 7 hp Kohler).
The Moline is long gone but still have the cub original engine here. ( I since replaced the head). Always kept it because it was a magneto ignition, not a battery coil setup.