This is a copy of a similar post from the Chevelle site about some timing covers and oil leaks!!
It concerns a very specific area with respect to an oil leak issue and ONLY on the SB's.
At first I was going to "condemn" ONLY the off-shore pieces, but now have to include possibly G.M.'s own GMPP timing cover with the "Bow-Tie" logo. I can't confirm it to be a "genuine" G.M. piece, but it has the "Bow-Tie" logo impressed into it!
That last statement MAY only apply to some "older" pieces, as I've just received 2 new ones and they are "good-to-go"!
A member of the Chevelle forum (Tom Mobley) "spotted" this issue, before I was ready to make this post, from a couple of photos on a "storage" site!
He made an excellent "internet-diagnosis" in reference to the following really!
Many of these "off-shore" pieces, they are available both "Chromed" and "Plain", are using "spot-welds" for the oil-pan front seal retainer "trough" for the pan gasket. What we've known for some time was the fact that the oil WILL find it's way out BETWEEN the spot-welds. When they do the actual welding it makes the "strip" sort of "raise up" between the welds and worsens the problem.
As a result of this procedure, after the unit heats up and the oil "thins" some, and the "crankcase-pressure" goes "positive", the oil is "forced" out between the welds. What makes it really impossible to detect is the fact that the oil will be "blown" away while driving but remain as "drip" of oil at the bottom lip of the pan as everything cools down. It's not as easy to diagnose as you would think. Most times the timing cover seal is "condemned", changed, reinstalled (same cover still), only to leak again!!
Simply put, there is NO WAY to stop this particular leak, it is one "faulty" design for sure! We gave up using these covers about 25 years ago when the front seals would "pop" out!!
(Add) The original G.M. SB covers use a "hermetic-weld" process to insure against these leaks, it makes little difference how much/what type of sealer is used in that area, it WILL leak, period!
Thanks, Gary in N.Y.
P.S. Here are some photos showing the issue!