Rear Main Seal -- leakleak..leak.
 

Ok, so i have a puzzle here , we have a 289 in house that is driving us nuts.

it is a 2pc rear seal, and it has been sleeved. (rear main) the sleeve is .08" larger than stock OD and we have tried stock type neoprene seals and a rope-graphite seal - and it still leaks.

Neoprene is inserted into clean channel with permatex 400 sealant.

-we checked crank case pressures and PCV setup and they are good, compression is 120psi on all cyls and leaks less than 5%. --so it is not blowby.

any ideas >?

--Steve

maybe around the threads on the flywheel bolts???

Just so I have this right: You have fitted a 'seal surface saver' type sleeve to that area of the flywheel end of the crank. It is 0.080"[eighty thou?] larger in dia , that a huge dia increase to expect the std neoprene seal to work with and even the existing seal groove in the block would need a rework for crank & seal clearance. Sure you dont mean 0.008" [eight thou]. The 351w/c cranks are larger in dia, but you would need a major rewok of the seal groove & crank to make that work. Might be leaking threads as Jerry mentions, but better get a handle on these dias first.

Have you put dye in the motor??
 

PANAVIA Steve have you done a leak dye check on this? I want to make sure it is ONLY coming out of the rear main seal. I am not sure why you added a sleeve to the crank shaft unless there was grooves or damage to the end where the seals sits.
Couple of questions, First, does the sleeve have small grooves in it, or is it just smooth? Most cranks that run rope seal need to have grooves pull the oil back into the motor. If the sleeve is smooth, there should be a seal in the kit. Smooth means most of the time neoprene. Most only work one way, you can mount it" the seal" either way.
Rope seal is always going to leak a little. I have gone through this with my FE motor, Pont 400 & 455 motors, AMC motors, There are specials tools for installing them. You are going to need to remove the engine for this installation. I know this S#$%%&KS. K&D tools sells a kit for sliding the rope seal into the motor, it will slide the seal but doesn't compress it into the groove and in a couple of weeks you will have a major oil leak.
Pull the motor, drain all fluids first. Put it on an engine stand, R&R oil pan and pickup. Loosen all the caps( keeping them in order) remove all the rods also. You need to make it so you can remove the crank to reseal the back on the motor. Depending on which seal you go with,
lets say we are back to the rope seal. you need a old rolling pin or a large dowel to push the seal into the groove all the way around. You need to do this on the cap for the crank also. Cut the ends with a SHARP razor blade with a straight cut. Try and have the ends flat as possible. Once you have this done, remove the rope seal and add a thin little bead of grey RTV sealer under the rope seal. Everything must be clean and dry of oil for this to work. Get the rope seal and put it into the block. Turn the seal about 10-15 degrees. Install the crank back into the block. You are going to do the same for the end in the cap also. Put a thin bead of sealer in the cap under the rope. Add RTV to the sides of the cap if needed. Add red forum a gasket where the block and cap meet, Thin coating. Put a small dab on both ends of the seal and install the cap and torque all to specs. Leave this setup over night. Then reinstall the oil pan, rods, and other parts. This has worked for me over the years. That's to say if the crank is straight. I have not had alot of luck with Neoprene seals. I stay with what the factory used when the motor was built. If you get a drip the size of a dime to a quarter, you are doing OK. Rick L. If you want to talk about this more, send me a PM.