As a temp fix, I sealed one that has lasted from one season into the next anyways. I had a customer that I did that for and at one spring PM and the next spring it was still holding well enough. Maybe it is still holding. First thing to do is remove the loose top cover bolts, clean up and loctite them. Usually it is the front 5 or so. I bored a hole 1/2 way through the block at the bottom of the crack to prevent further cracking. Roughing the area up some might be a good idea too. Clean the crack area w solvent- I used spray carb cleaner so I could clean the crack. I cleaned it with acid in the end and once dried, JB welded it.
Kohler did make changes to the block starting last winter to hopefully lessen this from happening. Before that they added an extra boss below the valve cover to give manufactures a place to bolt a muffler support bracket to help mediate the stress there. It is SOP to remove the shroud and check the bolts for looseness for me when doing maintenance on them. Loose bolts again should be loctited and resecured.

Thanks, tomplum.

Good suggestions - You say you drilled 1/2 way through the block at the base of the crack - how deep would that be? (I believe I've heard of that "trick" to stop a crack before, maybe it was in another life)

When I took the shroud off I couldn't believe how those five bolts had backed off - almost like it was done purposely. Checking them will definitely will become part of my maintainence regimen. Loctite blue - is that the preferred product, and to what torque?

I think patching it is worth a try, if for no other reason to buy some time. One site I searched suggested draining the oil and tipping the unit away from the cracked area to reduce chances of oil being present while the patch is forming/curing. Maybe this will work out OK after all.

Replacing the engine or buying another machine isn't on my radar screen in the foreseeable future. I figure this is worth a shot.

Thank you for your first-hand advice.

Ron

While drilling a hole at the end of a crack is a long standing practice to stop further cracking, I doubt just drilling half way is going to have much more affect than just leaving it alone.

Walt Conner

Then would drilling completely through (a very tiny hole) be any more harmful that having a fine crack, if it would stop it from spreading?

(I have no idea how thick that wall is)

Ron

I just remember not popping the drill all the way through. From the outside of the block, it's tough to know how thick it is! My guess is it de-stresses it some and I didn't want to fully rely on the JB to fully seal the 1/16th hole and oil to get behind the patch. One would hope that there is not much stress anyways once the top cover is tightened and secure. Next cam that goes in, I'll get a measurement for those that may want to know. Red loctite or blue. My guess is if there is an internal failure, it wouldn't be opened up anyways w/ a cracked block.
I've only done the patch once to help someone out. If the tractor is in good shape, short blocks for these are not bad $ if I recall. You were looking for a winter project? :) Hopefully by now the new style block is in the pipeline.

You make an interesting point about not drilling through the wall and allowing oil in behind the patch material. I hope to get at this repair attempt before long.

I think a short block runs around $500, a complete engine $950.

Meanwhile, I'll try and find out just how thick that wall is.

Ron

"Then would drilling completely through (a very tiny hole) be any more harmful that having a fine crack, if it would stop it from spreading?"

Would be better EXCEPT for getting cuttings inside the engine, not good.

Walt Conner

Well, here's an overdue update on this crack situation.

Figuring there was nothing to lose, I removed all the cover bolts, cleaned them as best I could and applied blue Loctite to the threads and re-torqued them.

Then I drilled a 1/16" hole at the base of the crack to stop it from spreading. Unfortunately, it went all the way through -
:>( - not a very thick wall, I must say. Oh, well.....

After that I "V'd the crack out with a Dremel grinder, cleaned the surface thoroughly with acetone and applied JB Weld to the surface. After letting it cure thoroughly I refilled the crankcase with oil waited to see if anything leaked. After about a week, there was an ever-so-slight damp spot showing beneath the JB Weld in one or two locations. I drained the oil again, cleaned the surface with acteone, and applied a coat of Permatex Ultra Copper silicone (a tip I found in another tractor site) and let that dry thoroughly.There was no sign of weeping after refilling this time.

So far it's been run about 15-20 hours over the winter hauling firewood, etc., with no sign of leakage, so I'm happy. How the summer heat affects it remains to be seen, but I don't have the stomach for a new engine (530 hours already built up on this machine) or buying a new tractor ($$$), and I'm cautiously optimistic it'll hold up .

Nothing ventured, nothing gained, as the saying goes.

This post was edited by anvilhead on Tue, Mar 12, 13 at 19:59

Hmmm, interesting choice on the silicone. Yes, report back. The one I did is ugly as ever but holding as of earlier in the month. I don't think it gets many hours anymore though.

I am suprised the JB weld didn't work, maybe the surface was too smooth. When I apply JB I usually ruff up the surface to give it something to stick too... Along with above Interested in if Permatex will hold also when the heat it on???

Darn, I misplaced the part # for that oil trough retrofit kit....

I was/am a bit skeptical of the Permatex idea, too, however one guy claimed because it flexes it's resistant to breaking open, and swears it (all alone) worked for him.

Permatex Ultra Copper RTV Silicone packaging claims it's good for up to 700F intermittent temperatures.

It's worth a try, I guess.

A follow up after 9 months and 62 hours of service, for anyone that's interested - the repair is still holding strong, no leakage, and I check the bolts regularly for signs of loosening.

I guess if there's anything to be learned, it's that it's worth trying a simple fix before going a more expensive route.

i had a kohler courage built in 2006 that cracked bolts came loose if you take a picture of all 4 sides of mower not engine bring it to a koher dealer they will send a new block free i just had to pay 120.00 labor.the dealer submitted it for me.he said they are not turning any down they are fixing them all.

the place you bring it to has to submit it to kohler they need the info on the motor and under the seat.

Interesting. Last I heard they were doing a special policy up to 3 years out of warranty. Not that they shouldn't cover these longer...
If I had to seal one again, I think I would clean it up and use that Great Stuff gasket maker.

This post was edited by tomplum on Fri, Nov 8, 13 at 17:10