Rear Main Seal - 1959 390

[P. Manoogian]

I have read all the threads and feel this job, on a lift, should not be difficult. However, my experience with a 61 390 is that the upper half was in tight and I had to remove the crank. Given that the 59 used a rope seal, am I likely to have the same problem ? I am replacing with a 2 piece rubber seal. If you have had experience with the 59 390 rear main I'd very much like to hear from you.
Thanks

[Bobby B]

Look into seals made by "Best"......
                                            Bobby

[P. Manoogian]

Already ordered FelPro.

[Dave Shepherd]

Careful here some cranks that use rope seals use a lightly knurled surface on the journal, neoprene type seals may not seal properly, not sure if the 390 is made this way.

[Roger Zimmermann]

Mid-58 there was a change: the more recent cars had no rope anymore but the neoprene seal. Therefore your '59 has the neoprene seal.

[Jay Friedman]

I've done it twice on '49s, once on my own car and once on a Art Gardner's.  In neither case was the crankshaft removed.  The key is to loosen but not remove the 4 front main bearing caps.  You can't see it, of course, but this causes the crankshaft to "droop" a few thousandths of an inch and which then lessens upward pressure on the seal.  You can then easily remove the upper half by screwing a wood screw into one side of the seal whose head you then grab with a pliers.  You pull on the pliers and push on the other side of the seal with a soft punch (brass is best so as not to scratch the journal) and out it will come.  '49s originally had rope seals but Terrill Machine in Texas sold us modern Neoprene seals which fit and worked perfectly.  No leaks after several years.  Don't know if this will work on a '59.  If you want I can send you a "step-by-step, how-to" article Art wrote on doing this. 

[P. Manoogian]

Jay,


Thanks for the explicit response, and yes, I would very much like to see that article. It makes great sense.


Peter


pm-1963@hotmail.com

[76eldo]

I just replaced the rear main seal on a 65 Corvette with a 327.

Once the pan was dropped I removed the rear bearing cap which has the seal in it.  I was able to carefully push up on the upper seal and push it up and around and then grabbed it with needle nose pliers and pulled it out.

I bought a FelPro replacement seal.  It came with a small plastic guide that you use like a tiny shoehorn and insert this little slip if plastic in the gap towards the block.  Then you start the seal into the gap between the crank and the block and this little slip of plastic keeps the end of the seal from grabbing on the metal and it slides right around the crank.

Follow the instructions and make a careful observation of how the old one comes out because there is a taper on the edge of the seal that keeps the oil from splashing past it.  Look carefully at this offset and make sure you install the new one facing the same way.

I am assuming that the seal is quite similar to the Chevy type.

I used Permatex Avaiation sealant which is non hardening on the ends of the seal and on the pan gasket.  Use some sewing thread to tie the pan gasket through a few of the holes to keep it from sliding around when putting the pan back on.

Brian

[P. Manoogian]

Thanks Brian. Good advice!

[P. Manoogian]

So I took the pan off along with the rear bearing cap. The seal that had oil on its face was the one between the pan and the cap. The rear seal, although hard, is a neoprene seal. The lower half was tight in the rear main cap. I am concerned about the upper half being equally tight and if i start poking at it I will "cross the rubicon" and could end up having to remove the motor and crank to finish the job.[/size]





I think I will try replacing everything but the upper half and see if that works. It only took one hour to get to the pan off.


I would be interested in any feedback on all of this.

[76eldo]

I'd try prodding it with something that won't tear or harm it.

It's got to be pretty oily and has nowhere to go but follow the curve and start poking out of the upper area.

While you are in this deep it would be a shame not to replace it.

Brian

[P. Manoogian]

Yeah, been watching You Tube videos. Seems like you have to find the right punch and hit against one side, then the other, etc. until it breaks loose. I agree with the "such a shame " part.

[76eldo]

If the 327 that I recently did was anything like the 390, I pushed on it with a screwdriver and it squished right out.

At the most you should only have to loosen one or two more main caps to get more clearance back there to get it out.

I didn't look in the shop manual on this.  Any info in there that may help?

Brian

[Jay Friedman]

Have you loosened the 4 front main bearing caps as I suggested?  This will take some pressure off the top half of the rear main bearing seal.

[P. Manoogian]

I can do that but I just talked to a guy who worked in a Cadillac dealership and he told me that it is not uncommon for some to be so stuck in the block that he did, at times, have to remove the engine. Judging by how strongly attached the lower half was to the main bearing cap today, at this moment, I am leaning towards leaving the upper half alone.


What was unusual about this leak is that it would leak overnight leaving about a 12" x 4" strip of oil. I have seen real mains leak before and they usually leave a round spot. That is why I think this may just be the pan gasket.


Today I will turn over the 1962 390 rotating assembly/block I have on an engine stand and experiment with removing that. I'd rather try the suggested "techniques" on a spare motor than on the 59 that I can put back together in under 2 hours and THEN remove the motor  it next spring.

[P. Manoogian]

Well, I have crossed the Rubicon and have started to remove (at this point trying to dislodge) the upper half. I have many pointy pick-like tools. Also spraying lots of carb spray after shoving the nozzle up in the seal area. 4 of the 5 mains are loose. No luck so far but I have resolved that if I can't get it out the motor will have to come out. I will keep you informed.

[Dave Shepherd]

Try prying down on the crank to gain a little more clearance.

[P. Manoogian]

OK, good news and NEW tips for all you guys who may want to try this...I got it out...


NEW Tips...


1.) Yes, I did loosen ALL the main caps.
2.) Use a medium fine screwdriver to bend the integrated metal of the seal lip TOWARD the crank creating a gap between seal and block area that is cut for the seal
3.) Get a can of carb cleaner with the thin red nozzle, insert the nozzle in the gaps on both sides of the seal against the crank. Spray until it pisses out everywhere.
4.) Turn crank with 1/2" socket on one of the 4 torus plate bolts...rotate crank while applying pressure against metal of seal with screwdriver.
5.) Repeat ....bending metal..spraying...rotating...over and over
Eventually it broke free and I could "roll" it out

[76eldo]

Now that you have cleaned it, try penetrating oil to get it to slide.
Tap one side, then the other and see if it will move.

Brian

[P. Manoogian]

It wasn't the tapping as much as the bending back n forth with the carb spray to loosen and soften the seal.