I just got the motor running today to break it in after a winter long rebuild and it sounds great with instant throttle response, im actually amazed as this was my first yblock build, 292 .40 over with cruise night special cam and a lot of other goodies, I cant wait to get this in the old truck, while running I noticed a little oil being thrown off the flywheel, not bad but it was leaking, im going to pull bellhousing and flywheel and check into it further, if it is the main can I do anything to fix without pulling motor apart ?  any ideas are appreciated, I couldn't have done the build without the help from here

What type of seal did you use, the rope seal or a neoprene lip seal? When I bought my Merc it had a pretty good leak; turned out whoever built the engine in installed the bottom half of the lip seal backward. 

it was the rope seal, its what came with the gasket set I bought

Did you soak the seal in oil for a few hours before you installed it? They will leak and even burn up if you don't that. Is the leak just a few drips or does it dribble out or more? Engine sealing technology back then just wasn't as good as it is today; anything with a rope seal will mark its territory to some degree. If you decide to replace it there's a tool called a Sneaky Pete made by Lisle that will remove the seal and install a new one without having to remove the crank, although you will have to pull the pan and the lower seal retainer and loosen the main caps enough to lower the crank to gain access.

Hmmmm...  After being put in service, the rope seal MAY swell, airman.  -They're suppose to.  BUT, if it continues to leak, consider doing what follows.  It's less work, takes less time, and has worked the two times I've done it on different y-block engines.

Click the following Forum website address for my newly revised earlier posting.  (hopefully, I've improved my explanation)
http://forums.y-blocksforever.com/Topic106586.aspx?Update=1

Hope this helps.   


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

There are several areas at the back of the Y engine that can make an oil leak look like it’s a rear seal leaking when it’s actually something else.  The rope seal does put the rear seal itself high on the list as they can be tricky to get right even for the experienced engine builders.  Other areas to check would be the rear seal retainer side seals, the oil galley plugs, and the cam plug.  The rear seal retainer not sitting square on the block either from warpage or residing on a piece of the rope seal is also another thing to look at.  If it is indeed the rope seal, then replacing it with a neoprene seal would be my own recommendation.  Here are a couple of links covering the rear neolprene seal installation instructions and warped rear seal retainers.
http://www.eatonbalancing.com/blog/2008/09/10/neoprene-rear-seal-installation-for-the-y-and-others/
http://www.eatonbalancing.com/blog/2009/06/28/warped-rear-seal-retainer-on-a-y/
 
The rear seal retainer itself can be a problem if it’s warped or cracked.  Here’s are pictures  of a cracked retainer that came out of a 312 which had been daubed heavily with RTV in which to slow down the leak.
 
 

Lorena, Texas (South of Waco)

thanks gus, no I didn't soak it , when I get the bellhousing off ill check around, thanks for the info, ill look into the tool, if I have to replace it the neoprene is definetly what ill use

Run it for a while see what happens..
You can replace it without pulling the motor. Follow Teds links. The only thing you will find is you wont be able to offset the neoprene seal if your doing it in the car, If you can your a better man than I. Mine still leaks after I replaced with a neoprene seal just the same, many have success, many do not .. welcome to the world of early Fords.. embrace it  ; o )



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