Honda HS928 Oil leak

[lefty]

SZAS-1170572

Engine GX270 GCAB-2462803

This came to me for service. It didn't run due to some carb issues and I was waiting on parts. Today they came and I noticed a puddle of oil under it. I thought It was a sump gasket leaking due to the location of the oil I can see. But I saw this on the left side of the sump cover. I can't tell if it's some sort of casting mark. It looks a lot like a crack to me. I included a photo of the other side. It has similar markings but doesn't look as server. There is a huge difference of depth on either side of the crack. I'm wondering if these are known for leaking in the sump gasket or cracking. Thank you.

https://photos.app.goo.gl/gwyyAzaFkE476NXW8
https://photos.app.goo.gl/yDrXWDZ6BQXgw1RE6
https://photos.app.goo.gl/iQtUG1kqg3s4rgQy8

Other side: https://photos.app.goo.gl/kNKQFgddZkFCZTEV7

[KE4AVB]

To be sure Lefty once you get the engine running use some UV tracer dye. Run the engine up to 30 minutes while checking every so often with the light. Depending the light source you may need a darken area to do this.

Oil leaks can be where you don't expect them. Just recently I had a Kohler CV20 to have a cylinder head leaking which appeared to the valve cover or possibly a head gasket. It was neither but was pin in the cylinder head between the two bolts. I even had a Honda to leak during operation that you would swore to flywheel side oil seal which turn out to be the fill cap seal.

Yes casting areas can look like cracks when they are not. The only way to sure is the use of the UV tracer dye.

[lefty]

Thanks. How much of the dye would be adequate for this application? I've never used it before. Would I just pour some in and run it for a bit?

Thanks.

[bgsengine]

most dye comes with instructions - you want to use care with opening and pouring it - no stray drops and keep it off your hands (The stuff can make a hell of a mess if you arent careful) typically not even a capful of dye - What I do is poke a vent hole in one part of the bottle seal and then with pocket knife cut a little notch for pour control, then you can pour out a small measure (half teaspoon or so) into your measuring cup (I dont recommend using the cap!) and add it to whatever (oil fill in this case) taking care not to spill or smear any on the outside of filler tube or hole (Or use an eye dropper if it is a filler hole) and then top off oil to full, run er half hour or so (or get it to operating temperature) and shut down, let it sit a bit, switch on your black light (wear the glasses that come with it - UV light hurts the eyes!) and should see the leak/source if all was done right. Dye and/or blacklight should come with instruction sheet on how to and how much to use.

[KE4AVB]

One thing of note here. The UV wavelength must the dye wavelength. The 374CS dye I use here works best with 365nm light. Most UV lights are 395nm.