Help Please - Rear main seal rotating

Hi All,
looking for some help. Been getting my butt kicked by the rear main seal on my 78 200 six.
The engine leaked oil. I decided to change the pan gasket and rear main, while I had the trans out to fix the clutch.

Installed per the regular wisdom and the advice of my dad, a 25 year Ford mechanic. Since the engine sat for quite a while before running, I thought maybe the rear main seal had somehow flattened?

Put in in a new rear main seal and this happened:
IMG_3975_LI-2 by Craig Pike, on Flickr

Of course this leaked.

I was afraid I put in the seal too agressively and scuffed it. So I dropped the pan again and put in another seal. This time I loosened all the main caps. The seal went in perfectly. I rotated slightly so the seal ends weren't lined up with the cap/block and applied a VERY small mount of forma gasket to the ends. After torquing all the caps, the seal was in there snug. Put it back together, ran once, no problem... now it's leaking again. I'm pretty sure it'll be rotated again.

Have you seen this?

I'm not putting any adhesive or rtv or anything on the seals. The seal on the rear cap is LOOSE. it'll fall out if I don't hold it. The pin from the rope seal many moons ago is gone.

What am I missing!? This is really starting to make me angry!

That's frustrating !
First thing I'd do is re-order the rear main seal and compare it to the one(s) that slipped, may be an out of spec batch of seals ?
If the rear main cap is somehow out of spec in the seal area/surface,rope seals are not too terrible, you'd have to install the pin again but they did work fine for many decades....
Keep us posted,
DannyG

pikesan":wq294jx8 said:

Hi All,
looking for some help. Been getting my butt kicked by the rear main seal on my 78 200 six.
The engine leaked oil. I decided to change the pan gasket and rear main, while I had the trans out to fix the clutch.

Installed per the regular wisdom and the advice of my dad, a 25 year Ford mechanic. Since the engine sat for quite a while before running, I thought maybe the rear main seal had somehow flattened?

Put in in a new rear main seal and this happened:
IMG_3975_LI-2 by Craig Pike, on Flickr

Of course this leaked.

I was afraid I put in the seal too agressively and scuffed it. So I dropped the pan again and put in another seal. This time I loosened all the main caps. The seal went in perfectly. I rotated slightly so the seal ends weren't lined up with the cap/block and applied a VERY small mount of forma gasket to the ends. After torquing all the caps, the seal was in there snug. Put it back together, ran once, no problem... now it's leaking again. I'm pretty sure it'll be rotated again.

Have you seen this?

I'm not putting any adhesive or rtv or anything on the seals. The seal on the rear cap is LOOSE. it'll fall out if I don't hold it. The pin from the rope seal many moons ago is gone.

What am I missing!? This is really starting to make me angry!

Click to expand...

Yes Pikesan, that's quite odd! From your discription you installed the rear main seal the correct way by clocking it so that the seal ends don't line it up with the block and main cap parting line, your Dad is right! This was the Ford recommended method that was in their service bulletin many years ago.

The way I see it the fact that the seal is loose in the rear caps grove is what's wrong. What brand of seal is it? Who ever is manufacturing these seals probably isn't making it according to the factory Ford specs and maybe substituting a seal for a different engine. You could try another brand to see if it fits better in the main cap or else see if you can locate an orginal NOS Ford MotorCraft rear main seal.

This was a faveriote mod for me and if Ford made one that fit an engine I was working on then it was instaled during the rebuild after all they are free Horse Power! But I haven't built a new engine lately so haven't seen this problem before. All these type of seals I have ever installed in the past fit into the block and main cap grove’s snugly. Lastly if you can't find a good seal that fits properly you might have to go back with the rope seal for now. As far as the replacement pin I have made those out of a finish nail of the right diameter. Good luck

Thanks Bubba. I'm gonna try a different brand. I can get Mahle (JV730R) or National (5116) from RockAuto. Might just buy both and see how they fit. I guess it would be dumb to try another BS30135 Felpro.

By the way, Felpro's website said it's a problem with crush on the seal and to check my crank bearings? Not sure how to start there... everything else seems totally fine on the engine. (save some other dumb problems...)

Thanks!!

That’s troubling FelPro is the brand I preferred too! Then you would need to use a micrometer to measure the cranks seal surface diameter to see if it’s within spec. However if the seal fits sloppy in the grove I don’t think there is much chance that you can get the proper crush fit or grip to keep it from moving.

As far as changing out the crank bearings that seems a bit of a stretch with basically a newly rebuilt engine that they have anything to do with the rear main seal problem. So if you have the proper bearing clearance now, and if the main bearings didn’t have the proper crush fit in the block or main cap then you would be having issues of spinning one or more of the main bearings. Good luck edited

I like to have the mating of the seals at 4:00 o'clock & 10:00 o'clock.
I seal the ends with Toyota or Lexus sealer. Fibga
Get the sealer for engine oil sealing not the one for transmission sealing.
Its expensive close to $20.00 a tube. I like it better than permatex grey.
You also have to put a very small amount from the seal to the the edge of the cap where it seats in the block.
Most shop manuals show you exactly where to apply it.

wsa111":blrk2a1w said:

I like to have the mating of the seals at 4:00 o'clock & 10:00 o'clock.
I seal the ends with Toyota or Lexus sealer. Fibga
Get the sealer for engine oil sealing not the one for transmission sealing.
Its expensive close to $20.00 a tube. I like it better than permatex grey.
You also have to put a very small amount from the seal to the the edge of the cap where it seats in the block.
Most shop manuals show you exactly where to apply it.

Click to expand...

Thanks Bill... Except for the Toyota sealer, I did that. Unless 3.5 o'clock and 9.5 o'clock is a a terrible idea?

I think the biggest problem is the LOOSENESS of the seal in the cap. It will fall right out and rotates w/o effort. If one of the THREE new seals I ordered (all different brands and NOT Felpro) don't fit snug, I'll find a way to make it snug. I'm not into pulling the pan off... again. (although I'm getting good at it!)

The good news is.. I drove it into work for our "bring your kids to work" little car show. Even with a slight drip, I needed a little payback from my car. Next is to install the DSII you made for me! (after the oil leak situation!)

Go with the Felpro seal. Make sure the surfaces in the block & cap are bone dry & free of oil. Spray the areas with brake cleaner, & blow dry.

Did you get all the oil out of the groove before installing? I use alcohol and swab it out well.

Im just gonna go ahead and say something stupid. Why cant you silicone the seal to the cap to keep it from rotating? If you put it together while still wet the seal should self position and after letting it sit for a day or 2 the silicone should set and hold the seal from rotating. And i dont mean like gobs of it just a few small dots in a couple places.

Thanks for the responses guys...
All surfaces were super clean before reinstalling. That's not it.

I've tried 2 Felpro seals, the next one will NOT be Felpro. They're telling me something's wrong with my main bearings.

As for the silicone idea... Yea, I've been thinking about that...if I end up gluing in place, it won't be with silicone. I'm not worried about the seal, I just don't want it to rotate. When I compare all the rear main seal brands, hopefully I'll be able to pick one that'll stay tight. Stay tuned.

pike

Silicone is a great glue.. I do not offset the seal, do not think that it crush's right....I put them flush and run some silicone around in the groove and from outer edge of the cap straight to the seal stopping at the inside edge of the seal...Keeping in mind that a little silicone will go a long ways.

I cannot say that I recommend this but it works for what I am doing.

What they are thinking is that bearing clearance is excessive and the crank is wiping around and grabbing the seal.