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Anyone have any luck with a new Kohler short block for a CH742. Reason why is a complete engine is on back order till at least September, also short block is about $1k less. Just wondering if anyone has any input. Thanks.

That would depend on what is wrong with the current engine. What's going on with it?

VegetiveSteam said:

That would depend on what is wrong with the current engine. What's going on with it?

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It has a cracked ring and scoring on the cylinder walls.

Depends on the condition of the heads. Condition of the guides and face of the valves and seats.

Wow that's unusual. I don't believe I've ever seen a cracked ring on a Kohler. Like hlw49 mentioned, if the upper end, meaning heads, carb and intake manifold are all undamaged and in good shape a short block should be all you need.

Do you know how many hours are on the engine now?

If you're going to be installing the short block yourself the one tip I would give you is make sure you have the governor set correctly before you ever try to start or even crank the engine. If it's not set correctly and you try to start the engine you run the risk of damaging the governor gear and now you're going to have to tear the engine down to replace that gear.

I'd be inclined to see if they make an oversized piston and ring set that is available. Then give them to an automotive machine shop with the new piston and rings, and let them bore the cylinder out.

VegetiveSteam said:

Wow that's unusual. I don't believe I've ever seen a cracked ring on a Kohler. Like hlw49 mentioned, if the upper end, meaning heads, carb and intake manifold are all undamaged and in good shape a short block should be all you need.

Do you know how many hours are on the engine now?

If you're going to be installing the short block yourself the one tip I would give you is make sure you have the governor set correctly before you ever try to start or even crank the engine. If it's not set correctly and you try to start the engine you run the risk of damaging the governor gear and now you're going to have to tear the engine down to replace that gear.

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Unfortunately only 350 hours. Its a 2014 so its way past the 3 year warranty. It has not been taken care of. I installed new heads on it, cylinder 2 will hold compression, cylinder one will leak down. The leak is large enough you can hear a hissing from the crankcase (with rocker arms off of head to eliminate a valve cracked open by one)
where cylinder 2 does not do that. I have taken head off twice. With new head gaskets, new studs. Used a straight edge and flashlight checking for warps. I took the head back to machine shop and they vacuum checked the valve seats and everything checked out. So the only thing that is left is rings that I can think of. But a complete engine is on back order. Also a short block is backordered now. So i may tear it apart and get new pistons and rings. Also i will check on boring it out. Thanks everyone.

Jday123 said:

Unfortunately only 350 hours. Its a 2014 so its way past the 3 year warranty. It has not been taken care of. I installed new heads on it, cylinder 2 will hold compression, cylinder one will leak down. The leak is large enough you can hear a hissing from the crankcase (with rocker arms off of head to eliminate a valve cracked open by one)
where cylinder 2 does not do that. I have taken head off twice. With new head gaskets, new studs. Used a straight edge and flashlight checking for warps. I took the head back to machine shop and they vacuum checked the valve seats and everything checked out. So the only thing that is left is rings that I can think of. But a complete engine is on back order. Also a short block is backordered now. So i may tear it apart and get new pistons and rings. Also i will check on boring it out. Thanks everyone.

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If you have it bored I would NOT give them the piston unless you are 100% sure they know what they are doing. They don't need it. All the machine shop needs to know is the brand new bore I.D. and they simply need to bore it .010 or .020 or whatever it takes over that figure. I've seen it too many times where the machine shop tries to fit the piston to the bore and it ends up seizing because they didn't measure the piston correctly. Piston to bore clearance is different on an air cooled engine that it is on a liquid cooled engine. Kohler recommends simply boring from the new bore I.D.

The new bore of a CH742 measures:. There is .001" tolerance on a new bore. If your bore will clean up with .010 then it needs to be bored 3.2772/3.2782". They should double check the Kohler service manual for the correct brand new bore I.D. and not just take some ya-hoos word from the Internet.

Do you have the complete engine spec number you can share?

take the new piston in. I've seen pistons mislabeled. Meaning you get a box that says .020" over but it is .010" so now we are in trouble when they say that was the only one we have. Use the Kohler specs if they are available but do measure the piston. Also - did you see the scoring or are you guessing it is there because of the leakdown test?

I can see it. Its not terrible but its there.

Jday123 said:

I can see it. Its not terrible but its there.

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If you don't mind, post the spec number.

can you feel it with your fingernail?

VegetiveSteam said:

If you don't mind, post the spec number.

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CH742-3111

sgkent said:

can you feel it with your fingernail?

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I will have to check this weekend.

Jday123 said:

CH742-3111

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You probably won't find it in stock either but if you're really wanting a new engine a CH742-3112 is the exact same engine less the front drive shaft. Take it and the flywheel screen off your original engine and put it on the 3112 and now you have a 3111. Finding one may be a long shot but at least it's another option.