I have been in the automotive game over 50 years and there is NOTHING worse than what I call a BASKET CASE. It makes it almost impossible to figure out what was wrong intially and what and how the engine can be repaired and reassembled properly. So I feel for you because I have been there done that.
I had to go to a 1973 Olds in one of my data bases to find the limited information I have for you at this point. So let me give you that information and then I will try to follow up (as time allows) to get some additional and more specific information for you.
Here is what I have at this point:
- Remove the oil pan and rear main bearing cap.
- Remove the old seal from the bearing cap and place a new seal in the groove with both ends projecting above the parting surface of the cap.
|Fig. 1: Installing rear bearing cap oil seals — Buick built engines|
|Fig. 2: Apply a small amount of sealer to the split line — Buick built engines|
- Force the seal into the groove by rubbing down with a hammer handle or smooth tool, until the seal projects above the groove not more than 1 ⁄ 16 in. Cut the end off flush with the surface of the cap. Use a razor blade.
- On the 231, 252, and 350, place new neoprene seals in the grooves in the sides of the bearing cap after soaking the seals in kerosene for a minute or two.
- To install, reverse the above. Use a small amount of sealer on the bearing cap mating surface. The engine must be operated at low rpm when first started, after a new seal is installed.
NOTE: Although the factory recommends removing the crankshaft to replace the top half of the oil seal, the following procedure can be used without removing the crankshaft.
- Remove the oil pan and rear main bearing cap.
- Loosen the rest of the crankshaft main bearings and allow the crankshaft to drop about 1 ⁄ 16 in.
- Remove the old upper half of the oil seal.
- Wrap some soft copper wire around the end of the new seal and leave about 1 ⁄ 2 in. on the end. Generously lubricate the new seal with oil.
- Slip the free end of the copper wire into the oil seal groove and around the crankshaft. Pull the wire until the seal protrudes an equal amount on each side. Rotate the crankshaft as the seal if pulled into place.
- Remove the wire. Push any excess seal that may be protruding back into the groove.
- Before tightening the crankshaft bearing caps, visually check the bearings to make sure they are in place. Torque the bearing cap bolts to specifications. Make sure there is no oil on the parting surfaces.
- Replace the oil pan. Run the engine slowly for the first few minutes of operation.
The rear main bearing seal may be replaced without removing the crankshaft. Seals should only be replaced as a pair. The seal lips should face the front of the engine when properly installed.
- Remove the oil pan, and pump as previously outlined, and remove the rear main bearing cap.
- Pry the lower seal out of the bearing cap with a screwdriver, being careful not to gouge the cap surface.
- Remove the upper seal by lightly tapping on one end with a brass pin punch until the other end can be grasped and pulled out with pliers.
|Fig. 3: Fabricate an oil seal tool — Chevrolet and Oldsmobile built engines|
|Fig. 4: Removing the upper half of the oil seal — Chevrolet and Oldsmobile built engines|
- Clean the bearing cap, cylinder block, and crankshaft mating surfaces with solvent. Inspect all these surfaces for gouges, nicks, and burrs.
- Apply light engine oil on the seal lips and bead, but keep the seal ends clean.
- Insert the top of the installation tool between the crankshaft and the seal of the cylinder block. Place the seal between the tip of the tool and the crankshaft, so that the bead contacts the tip of the tool.
- Be sure that the seal lip is facing the front of the engine, and work the seal around the crankshaft using the installation tool to protect the seal from the corner of the cylinder block.
NOTE: Do not remove the tool until the opposite end of the seal is flush with the cylinder block surface.
- Remove the installation tool, being careful not to pull the seal out at the same time.
- Using the same procedure, install the lower seal into the bearing cap. Use you finger and thumb to lever the seal into the cap.
- Apply sealer to the cylinder block only where the cap mates to the surface. Do not apply sealer to the seal ends.
- Install the rear cap and torque the bolt to specifications. Install the oil pan and pump as previously described.
The crankshaft need not be removed to replace the rear main bearing upper oil seal.
- Drain the crankcase and remove the oil pan and rear main bearing cap.
- Using a blunt-ended tool, drive the upper seal into its groove on each side until it is tightly packed. This is usually 1 ⁄ 4 – 3 ⁄ 4 in.
- Cut pieces of new seal 1 ⁄ 16 in. longer than required to fill the grooves and install, packing into place.
- Carefully trim any protruding seal, being sure not to scratch or damage the bearing surface.
- Install a new seal in the bearing cap and install cap, tightening bolts to 120 ft. lbs. (162 Nm), 107 ft. lbs. (145 Nm), on V6 diesel. Install the oil pan.
NOTE: I can get you torque specs for the bolts or studs that hold the rear main cap if you need or want them. If the clearance between the bearing insert and the crank is within tolerance you might want to consider using a "Sneaky Pete" to install the upper rope seal, so you do not have to pull the crankshaft out.
Here is a picture of the Sneaky Pete tool, if you need it:
Let me know if you have ever used one of these to reseal the upper half of the crankshaft.
PS- I will look for a better picture for you and post it if I can find it.