If one used more liberal "RTV" type sealer than necessary, it can cause a lack of flow, or stop the lubrication oil.
I don't know your experience or abilities so I won't try to guess.
Review the lubrication diagram if you haven't, and that will help you determine
where the problem occurred in the system.
Also if it has a divorced oil filter, make sure the oil lines are routed so as the flow
into the filter is directed to the outside of the filter, and comes out of the center of the filter to lubricate the engine,
AND that it is the proper filter. (I use the larger FL400 Ford filter) it has a large flow, a good filter and is inexpensive compared to Kohler.
If the filter had a drain back check and it is hooked up backwards, bad things happen.
The fact that it ran 30 minutes makes me think that the flow was restricted by sealant or other debris
Do post back with your findings so we can help.
Those are my favorite engines and I have built a few.
