What to use to seal KT series crankcase

[Kenh]

First a little background

I have a Kohler KT 19 that is an oil leaker.  One leak is from the cylinder to crankcase caused by a bad gasket.  Easy fix with new gaskets.  The second is a bit tougher.  One foot on the crankcase has been welded.  Whoever did the welding did a VERY nice job, but when the sealing surface was machined, there is a little extra gap.  The sealant used was the old standby Permatex Avaition sealant that is brown in color.  It just isn't up to the job to fill the extra gap.  There is also one other spot up near the governor that looks a little funky.  Like the case halves were vibrating against each other. 

I've done a fair share of small engine repair and even wrenched in a dealership for a few years but never had an opportunity to work on the old KT series.  

So my question is what would be the best modern product to use to seal these case halves?  An internet search has suggestions all over the the place.  Mostly from the motorcycle community which I've also wrenched at a dealership.  A couple alternatives would be appreciated also,  in case I can't get one of them locally.   Thank you!!

 

Ken

Edited December 5, 2024 by Kenh

[Bill725]

FYI, motorcycles use ThreeBond TB1215. Toyota uses their P/N 00295-00103 for oil pan and camshaft housing. Not sure if they would work in the extra gap area. I suggest calling ThreeBond, Henkel/Loctite and Permatex for advice. Please report back.

Edited December 5, 2024 by Bill725

[Kenh]

The gap is not much.  Only .001 or .002 or .003 extra????  It's just enough the old school avaition cement won't hold up.   So I'm confident something with a little more body will work OK.

 

Ken

[Kenh]

I've used Yamabond in the past when I wrenched at a power sports dealership.  But Yamabond is expensive and the tubes will do 25 engine cases so really don't want to go down that road.

 

Ken

[CarlH]

Yamabond is premium in the motorcycle arena.  I have used it for a Command cover successfully.

[Horvik]

I found Indian head shellac tough to beat for those situations. Hope this helps out.

[Kenh]

That old Indian Head shellac is what was used to seal the case previously.  It just didn't have enough body to seal that extra gap, hence the leak. 

I wound up using a Permatex product #51813, which is an anaerobic cure sealer.  Loctite has a similar product #518.  Anyway I had a chance to see it work as I forgot to reinstall the tab that holds the oil feed pipe in place.  It gave a very good seal and the case halves were fairly easy to separate.  It cleaned up easy with some light scraping and some lacquer thinner on a rag.  I see no reason for this case to leak.  

I have yet to to run the engine as I ruined the case closer gasket. (The cover on the PTO end)  I had to order a new gasket.  Speaking of which... I ordered one of the $15 sets off E Bay.  I was happy with the fit and quality of the gaskets.  I ordered a second set for the closer gasket as the set was only a couple dollars more that just the single gasket from other suppliers.  

Ken 

[Kenh]

Well I got the whole engine back together and installed it in the frame.  Got it all hooked up, added oil and then discovered the fuel tank grommet leaked.  See my other thread.    So it was a day or two before I got back to it.  Walk in the shop and found a puddle of oil on the floor.  I had "several" words about that!!  So I pulled the engine again and after some looking I found the leak.  It is right where the closer plate and the split in the crankcase is.  For some reason the case halves don't meet meet up correctly there.  It's enough the gasket won't seal.  I need to get to town and pick up some silicone seal for that spot.  I think an air cure product would be best there. 

Like Roseanne Roseannadanna says.... It’s always something! If it’s not one thing, it’s another!

 

Ken

[Brettw]

I cannot say for certain, but those case halves are generally machined together and shouldn't have all of the issues you are describing.  My thought would be that someone in the past has married two halves of two different engines.  I wonder if all of the effort you are putting into this may be a short term fix if there are other alignment issues, such as crank and camshaft journals, etc.  Maybe find a blown engine with good block halves and start anew.  Just a thought, I know how these can become expensive to rebuild and I would hate to see all of this work and in the end, it's was an effort in futility.