Annoying banjo rear oil leak

[phartman]

I rebuilt the '48 open drive banjo rear in my pickup 1,000 miles or so ago. Everything runs great, but it has developed an annoying leak, the 6 o'clock bottom bolt and the 8 o'clock bottom bolt on the driver side of the differential. I'm referring to the bolts that attach the bells to the center section. The oil will seap out the bolt threads, it seems, while the rear is hot- following a drive- and continue to weap while the car is sitting.

It will leave an oil spot about the size of a silver dollar, and slow down as the lube cools in the center section.

All the other bolts are dry, as are the drain plugs.

Any solutions? Any kind of gasket sealer I can use to stop the leaks? Put some gasket seal on the threads and retorque these two problem bolts?

Thanks for your help, guys.

[37 Coupe]

I have had the same annoying leak after rebuilding mine. Make sure you have not used lockwashers on the small bolts to banjo, the bolts are supposedly designed to seal themselves at the shoulder. I have tried different sealants but next downtime I may drain pull one at a time,clean the best I can and use good ole Permatex. This is definetely an area that was not one of Fords better ideas,it would have been a better design to have blind tapped holes,but Ford probably thought this was an easier machining process. Probably never counted on a customer worrying about it 75 years later!

[my4dv8]

Drain the oil overnight . Spray copious amounts of degreaser into the offending holes with the drain plug still out of diff, carb cleaner should be used when you think all oil is gone from threads. Use Loctite or similar thread sealant on threads before refitting bolts. Leave a day or two before refilling. This worked for me.

[phartman]

I was told by a friend that the threads are oversized, and they were supposed to provide the seal through the tightening process. It was a 1-time use item, and the supply of unused bolts is gone and they aren't being repopped. Don't know if that is the story or not.

It is just odd that only two leak and the others don't....

[David J]

Did you happen to run a tap in the holes as part of the rebuild ? It's the holes that are tight - like the holes for the head studs . There's folks here that know the tech stuff on this sooz izza ottahear .

Originally Posted by phartman

I was told by a friend that the threads are oversized, and they were supposed to provide the seal through the tightening process. It was a 1-time use item, and the supply of unused bolts is gone and they aren't being repopped. Don't know if that is the story or not.

It is just odd that only two leak and the others don't....

[PeteVS]

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Removing the offending bolts, cleaning up the male and female threads and then using some Loctite PST or blue stuff might work.

[phartman]

Originally Posted by David J

Did you happen to run a tap in the holes as part of the rebuild ? It's the holes that are tight - like the holes for the head studs . There's folks here that know the tech stuff on this sooz izza ottahear .

How about this: "The seal is provided by the mechanical action of the threads."

Is that a better of expressing what is going on? Ain't enough mechanical action. Don't you hate it when that happens???

Dunno. I was an English major. You give me something William Faulkner wrote, I'll tell you what that man was trying to say.

[Vergil]

When rebuilding a banjo rear end with new seals and etc, I think it is a good idea to install a breather to keep pressure from building up in the housing forcing oil out at the weakest point. I also use permatex 2 on the bolt threads.I like to install the breather out close to the axle seals in the bell.

Vergil

[alan]

get some dental floss, back out the offending bolts-wrap about 1/2 dozen times around each bolt and run them back in-worked for me

[David J]

Definately not an english major here as should be real obvious . The threads in the banjo housing are supposed to be " tight " . This has been brought up recently . Same deal on head studs . A regular tap cuts them out to normal-sloppy spec . The way sealing bolts-nuts is addressed on my old JD tractors is to put lead washers on the studs so when you tourque them down the lead squeezes into all the gaps . Crude but effective .

Originally Posted by phartman

How about this: "The seal is provided by the mechanical action of the threads."

Is that a better of expressing what is going on? Ain't enough mechanical action. Don't you hate it when that happens???

Dunno. I was an English major. You give me something William Faulkner wrote, I'll tell you what that man was trying to say.

[phartman]

Originally Posted by alan

get some dental floss, back out the offending bolts-wrap about 1/2 dozen times around each bolt and run them back in-worked for me

I was actually thinking about plumbing Teflon tape. Any downside to the floss or Teflon tape???

[ford38v8]

Locktite thread sealer

[1931 flamingo]

Try swapping the leaking bolts with some higher up on the banjo?? Nothing to lose.
Paul in CT Also, everything I've read here or on other forums says DO NOT chase these holes, same with head stud/bolt holes.

[phartman]

Originally Posted by 1931 flamingo

Try swapping the leaking bolts with some higher up on the banjo?? Nothing to lose.
Paul in CT Also, everything I've read here or on other forums says DO NOT chase these holes, same with head stud/bolt holes.

I agree. If I had chased the holes, seems likely that ALL the bolts would now be leaking.

That Locktite suggestion seems reasonable as a fix.

But I am fascinated by the idea of wrapping the problem bolt threads with dental floss. Waxed? Flavored? That J & J floss my wife buys does leave me mintly fresh....

[G.M.]

I drive a number of V/8s and find some leak as you describe. I retighten the bolts TIGHT and it stops and a few years later they may be 3/4s of a turn loose again. This is on several cars. I suppose the real fix would be to put permatex on the threads. G.M.

[37 Coupe]

I also say good gobs of good ole fashion Permatex,I have tried the blue Loctite and leaks are back and have tried RTV now the next time I will clean real good and get back to basics.

[phartman]

Originally Posted by G.M.

I drive a number of V/8s and find some leak as you describe. I retighten the bolts TIGHT and it stops and a few years later they may be 3/4s of a turn loose again. This is on several cars. I suppose the real fix would be to put permatex on the threads. G.M.

Well, well, well.... On a whim, I crawled under the pickup just now and checked the tightness of the two offending bolts. They were noticably looser, just like the 3/4 turn you predicted they would be. Also checked the non-leakers, and yup, they were tigher.

Hmmmm. Could the remedy really be that simple? Dunno, I'll keep you posted.

And just to do this correctly, can anybody tell me the torque specs for these bolts that attach the bells to the center section?

Thanks!

Pete
Richmond, VA

[alan]

I worked for an old mechanic who worked on vw engines-they would leak no matter what he did so he came up with wrapping the bolts with dental floss and it worked great-but if you just prefer to let it drip that is a Ford's way of marking it's territory, use flavored so the dog will lick up what is still leaking