To broaden this thread, I have the same situation and same problem with a B motor. It is so bad, I made a janitor for it so it doesn't leave a puddle of oil where ever I stop. My situation is the same right down to replacing the seal and somehow creating a leak. What is the recommendation of the forum (for both of us)?
Synchro909,
If you replaced the seal and somehow created a leak (your words), I would believe that your machine work is within tolerance, and the problem is with installation. Did you follow the instructions and pressure test the seal before installing the oil pan?
The Model B instructions are pasted below:
1) Two seals are supplied. The larger seal fits into the groove of the rear main cap (B-6327), and the smaller seal fits into the groove of the block insert (B-6335). The smaller seal will not fit properly in a poorly made reproduction block insert.
2) If desired, a replacement block insert with a groove identical to rear main cap groove can be made or purchased. In this case, discard the smaller seal and upon assembly, lubricate and carefully slip the seal over the flywheel mounting flange. A plastic sandwich bag placed over the flange will protect the seal from damage due to small burrs.
3) Thoroughly clean the grooves in the rear main bearing cap (B-6327) and block insert (B-6335) to remove all traces of dirt and oil, which may interfere with proper seal installation and sealant adhesion. Also, make sure rear main cap drain pipe is clear
4) Seat each seal with lip pointing towards front of engine (see figure) into its respective groove, and trim the ends slightly long to provide “crush” at the mating surface. A single edge razor blade and stationary disk sander work well for trimming and squaring the ends. Cut the pieces to be used long, and experiment with trimming and squaring operations on the cut off pieces.
5) Without the crankshaft in place, assemble the seal with its lip facing towards front of engine, shims, block insert, and rear main cap to the engine. Check to be sure the seal fits properly in its grooves, and is not distorted or offset relative to the rear main bearing.
6) Machine the rear slinger area of crankshaft as shown in the figure. Finished diameter shall be between 2.330 in. and 2.370 in., and concentric with the rear main journal within .001 in. to prevent whipping of the seal lip outward. Machine crankshaft to largest diameter between limits consistent with cleanup. Polish seal contact area of crankshaft to a bright smooth finish. Main bearing clearance must be between .0010 in. and .0015 in. to keep the crankshaft from whipping the seal lip outward. On final assembly, apply either an RTV silicone adhesive or Permatex #2 sparingly to both grooves and all mating surfaces where shims, rear main cap, block insert, and block meet. Avoid getting adhesive on seal lip. Also apply sealant to rear main bolts.
7) Before installing oil pan, and after adhesive has cured, test seal and rear main cap area for leakage by pressurizing the rear main cap drain pipe with motor oil to 10 psi and check for leaks.
8) If a Model B engine that has been modified to provide pressure to the connecting rods (drilled crankshaft) is using this seal, an additional oil pressure check should be done by pressurizing the rear main bearing groove that supplies connecting rod #4 to the anticipated pressure (50 psi?). If a leak occurs, it will usually be between the groove in the rear main bearing feeding rod #4 and either thru the shims or up or down the rear main bolts.
To use a one-piece seal, the replacement block insert with a groove identical to the groove in the rear main cap is manufactured by Dan Price. This part is recommended for high output engines.
http://www.dan4banger.com
Baypac is correct that the seal does not see much pressure. If the drain pipe is not obstructed, the seal is only subjected to slightly more than crankcase pressure.
Terry Burtz
