Blown Head Gasket Cub 107

[Avie02]

Good Evening Everyone,
I haven't been on in awhile so I hope everyone is doing well. My tractor has seen better days unfortunately.

I recently had it service at a local shop and that was a mess in itself. Came back running rough and smoking on start up but I adjusted carb and it seemed better but still smoked a bit on start until the other day I noticed it was putting out a lot of heat and thought I saw some smoke out the side of the block.

Mowed tonight and had headphones on(my mistake) as it was running aggressive and when I went to put it up the exhaust was glowing cherry red and you could hear a rough stroke idle.

Figured I'd get on here as I'm not certain the extent of the damage or how difficult of a repair this will be. Any suggestions on a possible gasket/rebuild kit would be appreciated, I have very little experience with small engines but I'm willing to learn as I have grown quite attached to this old tractor.

Sorry for rambling, I'm just a bit upset at myself for not catching this sooner. I greatly appreciate any advice you all could provide. Thanks.

[Jeff in Pa]

You need to resurface the head
https://www.youtube.com/watch?v=L1jFtTzLh7o


And here's how to replace the head gasket
https://www.youtube.com/watch?v=iuD8pzCe6aE

I HIGHLY recommend getting a Kohler head gasket with the "fire ring" ( sheetmetal ring around the combustion area ).

It MUST be retorqued after you run it the first time.

[Avie02]

Jeff,
Thank you so much. Is there anything else you would recommend while I'm doing this work? I'm really hoping to keep this thing for the long haul so I might as well do anything that is recommended now. Thanks.

[Cub70]

I would carefully remove all the carbon from the piston and combustion chamber area and put in a fresh spark plug. You can also put in some fresh new grade 8 head bolts while your there.

Like others have stated before, torque the head bolts down in two stages using 1/2 the manufactures head torque spec to start (in the recommended torque pattern), then torque head bolts at manufactures full head bolt torque. Run the engine for a little while then recheck the head bolt torque again, and your done. Torquing the head bolts in two stages (especially using a brand new gasket), will help evenly spread the compression on the new gasket and prevent warping the aluminum head.

TIP: run a tap into the threaded engine block head bolt holes to clean them out, then blow compressed air into the holes to clear them out. Debris caked into the threaded holes can negatively affect bolt torque.

Should look similar to this once it’s cleaned:
08D68C64-0D57-4758-AE09-9629C3C84335.jpg

0DC4FC6B-8481-4365-831B-569202B8722C.jpg

[Cub70]

Kohler Head Bolt Chart

6CB656E2-4E93-4C32-8380-AAEC75D31903.jpg

[jbrewer]

Also lube the threads before torquing.

Good tip about cleaning the threaded holes too!

[Avie02]

Thank you all for the timely support. I have ordered the gasket and plane the head tomorrow.

Quick question, I changed the muffler a little while back and can't seem to get a good seal where the exhaust elbow goes into the muffler. Any quick tips to solve this while I'm working on the other stuff?

Thanks again.

[Avie02]

Finally got the head taken off and figured I would post a few pictures so you guys could tell me if i'm about to overlook something more serious. Thanks again for all the help, i'm going to flatten the head tonight while at my fire station(won't be sleeping anyways).