Re: Sealing sump to crankcase housing
Permatex does make a surface prep and accelerator for this but most auto part stores don't carry it or heard of it which I use sparely by using cotton swabs. This way you don't waste the surface prep by over spraying it. With using the swabs you also can tell when surfaces are clean. I was surprised how dirty the surfaces were that looked clean to my eyes. But basically you are wanting the contact surfaces to be oil free. I get the surface prep through Amazon.
Kohler used Ultra Black on the engines that I torn down but Ultra Grey also works. However with either product you must follow the instructions with a couple exceptions. One is the curing time which I have found to be at least 24 hrs before you fully torque the screws; though, the Permatex instructions says 30 minutes. Basically the screws are initially finger tight until the sealer is cured. And two that no oil is allowed to contact the sealer during the same curing time frame; other words, don't add the crankcase oil until the sealant is cured. This is because once oil contacts the uncured Permatex it will not cure fully.
Finally don't over apply the Permatex as you only want a small amount of squeeze out. I just disassembled a blown Kohler Command that the tech didn't let the sealer to cure properly plus he over applied it. He reuse the sump gasket and applied Permatex Red version. By using it this way the sealer didn't adhere to the oily gasket or oily surfaces so this was also a problem. Second side effect was because he over applied and had added oil right away he ended up with the sealer half covering the oil pump filter screen. In least than 6 months the customer which was too lazy to keep his oil check blew the engine. It was quite obvious there was a major oil leak. This lack of keeping his oil checked and not getting the leak fix cost him a very expensive engine.
Before I started following the above instructions I was constantly having to reseal valve rocker covers every few months especially those hard to seal Kohler Courage single valve rocker covers.
Btw in my opinion the Black or Grey does look a lot better than the Red or Blue sealer I see used as matches the aluminum color better.