How bads the leak? We all want Perfectly sealed engines, but that's just not the case. They all develop leaks. The Builder did seem to try [2 times] and is just not able to get it sealed up. It may be a block issue as others and the builder suggested.

Lots of others have had issues getting that rear seal to not leak at all. Ive had good luck, but am worried every time I put one together. Fortunately, that's not often.

So how bads the leak, gusher, drips, seepage?? Oil fill, pcv valve, and vac hose/lack of vac can all contribute to leaks as well.