HG42 - installed new rear main seal.... and it still leaks

[mr.precision]

My Hercules engine manual states that the seal body should extend 5/64" past the bore in the bellhousing.   That would have to be measured from the back side of the bellhousing. Not easy to do with the bellhousing installed.   So one would need to measure the length of the bore and the seal width and figure out how far in from the front the seal should be.
The manual states that this dimension is important!

Thanks Robert. I spoke with Landis Zimmerman today about my dilemma.... he said the seal should be flush with the front of the bore and that there is no place in the bore for the seal to "seat", which I definitely felt when tapping it in. Maybe I pushed it right up to the back flange on the crankshaft. I agree that measuring, as you have stated, can be done.
So it will all come apart again and I'll keep the group advised of what the outcome is.

[Robert Barbour]

My manual is dated Sept 1952!!  That was when Hercules still existed and supplied seals!!  Today we get seals that are matched to the id and od of the old seals, not original seals from Hercules.  Therefore the seal lip may not be in the exact same place relative to the front and back of the seal body.  In the manual the diagram shows the seal back from the front face.  However if Landis said it should be even that is what I would do.  I rebuilt one 4 years ago and got the Parts from Landis and all work well. I don't remember exactly what I did!!  I have another parts engine which is in pieces, I will look at it over the weekend and see how things look.

[Robert Barbour]

 Looking through my parts I found a NOS bellhousing dated 6/14/7 , which I think is 1957, after OC 3 production ended, but while the 4 cylinder OC 4 was still in production.
This housing has never been used and has an unused seal in it, of the old leather type.  The seal is flush with the front and back of the housing as it is with in a few thou of  the same width.  I measured the housing at .605 inches and the seal at .585 inches.  The leather would contact the rotating surface for at lease the center half of the seal, a much larger area than a modern seal would.

[mr.precision]

Good info. Thanks for checking. The new style seal has a very small contact area. I will take everything apart again and report back to the forum what is found. I also will be looking for an alternative leak path while everything's apart. Maybe it isn't the seal.... perhaps something else.

[Blake Malkamaki]

Can you get a leather seal? They are much better for many applications such as this.

[Robert Barbour]

That is a good question Blake!  I can not give an opinion on Leather seals as I have never seen a new one.  All I have seen are on old equipment that has not run in a long time.  That would be a good question to ask Landis, if they are still available he would likely know.

[Blake Malkamaki]

Leather seals are better for applications such as in crawler tractors as they are much tougher and can take more abuse than plastic or rubber seals. They do, however, always seep a very slight amount.

Chicago Rawhide seals were originally made from leather and were until recent times.

[eliwhitney907]

if it is leaking as bad as you say I would check your crankshaft for slop as well as end play and I would dial it to make sure the end is not bent as all of those can take a new seal out almost instantly.  then I would look at that surface where the seal rides for irregularitys or grooves.  I have had to use speedy sleeves on bad surfaces before.  tip  if you are to install a speedy sleeve use an electric pan and submerge in oil at 400 degrees for an hour before slipping it on.  btw  seal and speedy sleeve are matched set.

[mr.precision]

if it is leaking as bad as you say I would check your crankshaft for slop as well as end play and I would dial it to make sure the end is not bent as all of those can take a new seal out almost instantly.  then I would look at that surface where the seal rides for irregularitys or grooves.  I have had to use speedy sleeves on bad surfaces before.  tip  if you are to install a speedy sleeve use an electric pan and submerge in oil at 400 degrees for an hour before slipping it on.  btw  seal and speedy sleeve are matched set.

I've used speedy sleeves on small block chevy cranks, at the timing gear end.....but where would you get one for this application?
How does one check the crank for slop while in place? Thanks for the tips... this is a little out of my experience range.

[ObsoElitist]

You can check it for end play. If the thrust bearing is loose the mains probably are too, and a seal wont last long. If that is the case, the seal should have worked for a while, so thats probably not it. Only taking it apart will tell.

[eliwhitney907]

I looked at some of those pictures and that the seal matches to the flywheel is actually good as if it came to it you could replace the flywheel and have a brand new surface for your seal. 

I am new to these herc engines but every time I have ever had to replace a seal there was always something either up-stream or down-stream effecting things.  I always see a leaking seal as evidence of some other problem and start hunting..   again im new to these hercs. good luck and hopefully you get the leak to stop.

[eliwhitney907]

oh to answer your question when you have the flywheel off if I judge the pictures right there should be a gap between the bell housing and the crank.  I would put a small pry in there and just see if it "klunks" when you exert a little force on the pry.  it probably wont as if it did you woulda heard it when you had it running but it is an easy test.  it is probably not bent either but we had the very end of a lugger crankshaft installed on a tug boat bend right at the flywheel when they hit a log.  we went through a few seals before we figured it out.