I was at a dealer today when a guy brought in a Hustler Z with a 23 Kawasaki engine that blew at 1400 hours. The problem is in the upper crankshaft seal. The seal begins to leak very slowly so that you don't notice any oil leakage between oil changes. After a few hundred hours of operating with the seal leaking the oil builds up on the cylinder fins. The oil collects dirt, clippings, etc and the fins become filled. The engine overheats to the point that engine seizure occurs. The problem is that you can't see the upper cylinder fins since they are under the fan cover, so you don't know about the clogged cooling fins. The dealer said he has seen 7 of these engine failures in the past 2 months. He said the problem seems to be on Kawasaki twins in the 15 to 23 hp models. Just wondering if anyone on the forum has experienced the problem and to let everyone that has these engines to be on the look out for possible trouble.