1967 GMC 305 V6 rear main seal

[gmcbrandon]

I am currently rebuilding a 305 v6 motor out of my 1967 GMC C3500 truck. I order gasket set from summit and got a rope style rear main seal part # felpro BS 40048. I am trying to find a rubber nos seal, not too confident in using a rope seal.......

As you guys can tell im new to this forum and is my first post so if you have any suggestions for future posts let me know thanks!!!

[DillonGMC]

I mess with Pontiacs and they use a rope seal. Just run a VERY thin bead of rtv in the center of the journal and it'll be fine. I prefer mega black rtv.

[motorcritter]

I use Loctite 5970 for sealing situations that involve fuel (gasoline or diesel) or engine oil or transmission lube. It's used for tricky, specific German car repairs- it stays pliable, is stable to about 400* F, and doesn't break down in automotive lubes. Not super cheap, but well worth the cost for peace of mind. If you've ever had to break down a Mercedes cylinder head or VW/Audi (or Porsche) transmission, or BMW rear end, to seal a leak, you would pay double the price to avoid not going through it again. On another note, I didn't realise that a garter seal was available for such an application, at least without machine work to accommodate it.
Posted via Mobile Device

[kwmech]

I don't know if this will help or not, but the 5.7 GM diesel (shudder) which had a rope seal would take a 460 ford neoprene. Had to trim the ends about 3/16, but I did it all the time. Don't know what the main diameter is on that old V6 is in comparison, but if you could get some measurements...

[19673ontree]

I never used a rope seal on the rear main before myself but I knew they used them ,

[imjeff]

The rope seal will be fine. That motor doesn't spin that fast anyway. BTW, I always loved those V-6's, from the 305 up!

Jeff

[gmcbrandon]

okay guys thanks for the great input and help. So I trying to cut and trim a rope seal and had very little luck, could have done a better job with a hack saw. What do you guys use to cut a rope seal? I tried to use razor blade and scissors, razor blade had best results but still wasn't really pleased with quality of cut...

[gmcbrandon]

yeah motocritter i actually worked at a mercedes dealer for the past 2 year roughly but moved back to an independent shop again, i have used 5900 loctite sealer and it is amazing and still have some in my box

[DillonGMC]

I always use an exacto knife with a new blade. Use very firm pressure and move it back and forth slightly. Only like a 1/16th or so. I have also used tin snips. But only when I got over excited and rtv'ed it into place first lol.

[LSGarage]

Originally Posted by DillonGMC

I always use an exacto knife with a new blade. Use very firm pressure and move it back and forth slightly. Only like a 1/16th or so. I have also used tin snips. But only when I got over excited and rtv'ed it into place first lol.

I think it was back around 2007 or 2008. I got a rear main seal kit from NAPA. It was Felpro, part no. BS40048. It was a two-piece steel & rubber style. I was able to install it with engine in the truck. I have a 1967 GMC V-6, 305E. I don't know if it's still available or not. Hope this helps.
Posted via Mobile Device

[gmcbrandon]

Yeah LSGARAGE i read the description on summit and with the same part number and it said rubber too...maybe i will try to get one from napa and see if its any different thanks for that info