Click on image for the lowdown. 
====
| | |
1 members (Hush),
73
guests, and
2
robots. | | Key: Admin,
Global Mod,
Mod | | | Forums66 Topics128,211 Posts1,057,475 Members48,473 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Oct 2013 Posts: 331 Shop Shark | | Shop Shark Joined: Oct 2013 Posts: 331 | I have found bits and pieces of information about this topic, but nothing definitive. I am wondering if anyone has a good part number for this rear seal conversion. Any help would be greatly appreciated.
1950 4100 - unrestored and driven weekly for almost no reason at all.
| | | | | Joined: Sep 2001 Posts: 29,270 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,270 | | | | | | Joined: Jul 2010 Posts: 592 Shop Shark | | Shop Shark Joined: Jul 2010 Posts: 592 | I recently had trouble finding that specific gasket. I found some internet chatter stating they had been discontinued (??) and the best alternative was the Best rope gasket. I did find one source that still showed the 4519S in stock. Link below. Not inexpensive. http://www.vintagegasket.com/rear-main-seal-44520.htmlMatt | | | | | Joined: Sep 2001 Posts: 29,270 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,270 | Best Gasket replied emphatically that 4519S Rear Main Seal is still being manufactured and sold by them. | | | | | Joined: Oct 2013 Posts: 331 Shop Shark | | Shop Shark Joined: Oct 2013 Posts: 331 | Hmm, $40 is too much. Thanks for the feedback guys.
1950 4100 - unrestored and driven weekly for almost no reason at all.
| | | | | Joined: May 2001 Posts: 7,438 Extreme Gabster | | Extreme Gabster Joined: May 2001 Posts: 7,438 | Do it right the first time with a $40 part or do it over and over again with an inferior cheap part? I guess it depends on how much time you have on your hands and how much you like pulling engines. | | | | | Joined: May 2005 Posts: 8,878 . | | . Joined: May 2005 Posts: 8,878 | The rope seal is OK if installed properly, which is not a simple task unless you have the tools as explained in the manual and if you've done a few before. Even then they seep a little oil.
Your best bet is the rubber seal.
The absolute best is have the block machined to take a modern pressed in single lip seal, but requires complete disassembly of the engine, a great thing to do with a rebuild. I don't have the link to an article about the conversion handy right now but some searching may turn it up. | | | | | Joined: Oct 2013 Posts: 331 Shop Shark | | Shop Shark Joined: Oct 2013 Posts: 331 | Do it right the first time with a $40 part or do it over and over again with an inferior cheap part? I guess it depends on how much time you have on your hands and how much you like pulling engines. I can do it right with a $2 rope seal just as easily as I can do it right with a $40 neoprene one. I was only interested in saving a little grief since the rope seals are somewhat of a pain in the [censored] to install. I've only been doing this stuff for about 35 years.
1950 4100 - unrestored and driven weekly for almost no reason at all.
| | | | | Joined: May 2005 Posts: 8,878 . | | . Joined: May 2005 Posts: 8,878 | In my experience you need to remove the crank to put in a rope seal.
The two piece rubber can be put in without removing the crank, just oil pan and bearing cap. | | | | | Joined: Oct 2013 Posts: 331 Shop Shark | | Shop Shark Joined: Oct 2013 Posts: 331 | In my experience you need to remove the crank to put in a rope seal.
The two piece rubber can be put in without removing the crank, just oil pan and bearing cap. There is a tool that is used to install rope type seals with the crank in place - although it does usually require loosening all the main caps and allowing it to drop down a little to give more room. I have done it both ways many times. Installing one with the crank in place with the engine in the vehicle takes a very skilled and patient craftsman. I remember having my first experience with this on an old Buick engine when I was about 18 years old.
1950 4100 - unrestored and driven weekly for almost no reason at all.
| | | | | Joined: Sep 2001 Posts: 29,270 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,270 | Sneaky Pete Tool for rear main seal crank-in-place replacement | | | | | Joined: May 2005 Posts: 8,878 . | | . Joined: May 2005 Posts: 8,878 | Yes, I tried that once, no very good luck. Better with the two piece rubber, faster, easier, and les chance you have to remove the pan and do it all again. | | | | | Joined: Mar 2005 Posts: 1,636 'Bolter | | 'Bolter Joined: Mar 2005 Posts: 1,636 | I've put in lots of rope seals. It's not bad when the crank is out and you can properly work the seal into the groove. Doing it while in the truck is not impossible, but it is not exactly easy either.
Also, it's harder to find a good rope seal maker now. They just don't hold up like they used to. or that has been my experience.
I would use the two piece rubber seal and be done with it.
| | |
|
|
