More Rear Main Seal Questions

[Michael Monson]

The rear main seal on my 1964 Deville was replace about a year ago with the Best Branded one from Caddy Daddy.  Leaks were immediate and my mechanic was concerned about the gasket from the start.  Knowing what I know now, does anyone know where to source a Rebuilder's Choice seal or possibly even a factory style rope seal?   The transmission will be coming out anyways.  Also, I will check the rear main bearing cap for the needed modification.  Thanks

[Jason Edge]

Did you do the bearing cap mod per the serviceman bulletin. There is debate regarding the different the seals makes (at least in my mind), however if you did the bearing cap mode and used the Best brand seal that would further point to one seal (i.e. Rebuilder's Choice) actually making a difference.

Here is the help topic link for anyone that has not seen it: Rear Main Seal Oil Leak Fix with Bearing Cap Modification   (Scroll down to my Nov 19, 2024 reply for my thinking on the issue).

[Michael Monson]

Not sure if the bearing mod had been previously done, I hadn't seen that service bulletin at that point. I do remember that the bearings are .020 over so at the some point the motor was apart.  The brand new Best seal instantly leaked more that the old seal, so ideally I'd like to do the bearing cap mod and Rebuilders Choice seal.  If I can't locate one, the BEST brand and bearing cap mod will have to work.  Thanks

[Jason Edge]

It is pretty much a given the leak will persist if bearing mod is not made especially considering it was such an issue that a Serviceman Bulletin was issued in 1965 for the fix. I would also say everyone without the knowledge of this fix (i.e. access to that serviceman bulletin) would not have made the mods. I know when I rebuilt my engine in 2012 I was unaware of the mods and just installed the seal that came with the kit. Regardless of seal you use ... since to me jury is still out .... I would definitely pull the the bearing cap, inspect, and make the mods if not already done.