The Stovebolt Site Forums The Shop Area Engine Shop 1949 Chevy 216 Rear Main Seal Replacement

OK, I've searched on this topic and only got more confused. There is a lot of conflicting information - when replacing the upper rear main rope seal the following have been suggested:

1. remove transmission, timing cover/harmonic balancer.... seems like a lot of work - is this really the best way. My crank did nor drop when the main caps were removed and the pry bar method from Stovebolt Tech Tips seems a bit irrational. Comments?
2. Yes or No to RTV sealant at the rope ends? Please explain.
3. If the modern Fel-Pro rope gaskets without asbestos do not last long (this is what I've read) whats a better solution?
4. To assist with installing the upper rope, some say to soak the rope in oil but others say no not soak in oil. If this seal is an oil seal, why not soak it?
5. What about rubber seals? Is this an option for the 216 rear main seal? Some say yes while others say no.

I'd really like to hear from you, especially if you have personal experience with this issue.

1. There is absolutely no reason to drop trans, timing cover, etc. The crank will drop enough by simply loosening all the main caps. Using two pry bars in the flywheel teeth will help lower the back of the crankshaft. Just a few thousandths, less than 1/16" is plenty.

If the seal is packed into the block and the main cap properly, and cut off flush, no RTV will be needed. It won't stay put, anyway.

3. I have no experience with the new-design seals, as I've got bunches of the older design ones around the shop. If it's installed properly, I don't see why a new seal wouldn't work, however.

4. YES! soak the seal in oil! it helps it slip over the crankshaft, and prevents damage as you install it.

5. I don't think the block and main cap design of the 216 will accept a rubber seal.

The seal installation procedure just isn't as difficult as some people will lead you to believe. Once the crankshaft is lowered slightly, thread a big sheet metal screw into the end of the old seal, and pull it out with a pair of vise grips. Turning the crankshaft sometimes helps to roll the old seal out. The installation kit from Lisle tools with the Chinese handcuff tool makes it a lot easier, but I've installed bunches of seals with nothing more than a piece of copper wire threaded through the end of the seal rope. The trick is to oil-soak the seal and roll it out on a piece of plate glass until it slides around the crankshaft easily. Pierce the end of the seal about 1/4" from the end with an ice pick, and thread a piece of solid copper wire about 1/16" in diameter and about 18" long through the hole. Twist the wire into a spiral until you've got a pigtail about 9" long.Roll the seal on a piece of plate glass or other smooth surface until it's about 2/3 of its original diameter. Thread the wire over the crankshaft, and turn the crank as you pull the seal into place. Cut the end of the seal off just above the wire and discard that piece. Take a piece of hardwood dowel rod about 1/4" in diameter and a small hammer and pack the seal tightly into the groove above the crankshaft. Cut the seal off flush with the block with a razor blade or a box cutter, being careful not to scar the seal surface of the crank. Pack the lower half of the seal into the main bearing cap tightly, and trim it off flush with the cap. Reinstall the rear main cap, retorque the main bearings, and install the oil pan. Nothing to it!
Jerry

As to seals, you might want to check this site.

www.bestgasket.com

Thanks Jerry - I needed a little encouragement. I will replace the upper seal using the method you detailed.

Drew - thanks for the gasket site!

If you are going to replace the main bearings than you will have to drop the crank as per the procedure in the manual. This is the ideal time to put in the new seal. I have just been through this process.