Questions and Answers

Ford Mustang Rear Main Seal Q. Vince, I have a 1991 Ford Mustang LX 5.0 liter H/B Automatic transmission with 133K miles. Over the past 6-months, I have replaced the valve cover gaskets, the oil level sensor and the rear engine oil seal. However, there is definite leak from the rear main seal area. The oil pan and gasket are fine.

I took it to the repair shop that performed the work, and they informed me it was leaking again from rear seal and they were going to place a sleeve around the shaft that makes direct contact with the seal. It is still leaking.

Is it possible to have an oversized inner seal or do you think the seal may have been improperly seated. Also, can the surface holding the seal be accidentally damaged, causing the leak? I would appreciate your expertise and knowledge in helping me resolve this.

Thanks in advance,
Jesus

A. That particular seal is very fussy about how it is installed. If it is not perfectly lined up and aligned with the crankshaft, it will leak again. Ford has a special seal installer that will assure that it is lined up perfectly.

You need to take great care installing it or, as you found out, it will just leak again. This is no slander to your mechanic, he just doesn't have the right tool to do it.