CJ3B Front differential drain plug won’t stop leaking

[taylorpjones]

Hello I’m new to the forum and owning a CJ3B and I’m hoping someone can help me. I have a front differential drain plug that won’t stop leaking. I’ve tried permatex PTFE thread sealant, Teflon tape, and now permatex the right stuff gasket sealer. I’ve also gotten a new drain plug but nothing helps. I don’t think it’s stripped as the plug goes in about half way good and tight. I’m torquing to 20 lbs. am I torquing to the right spec? Should I try teflon tape and the permatex sealant or gasket sealer? I’m completely flummoxed, please help!

[Rus Curtis]

Hello I’m new to the forum and owning a CJ3B and I’m hoping someone can help me. I have a front differential drain plug that won’t stop leaking. I’ve tried permatex PTFE thread sealant, Teflon tape, and now permatex the right stuff gasket sealer. I’ve also gotten a new drain plug but nothing helps. I don’t think it’s stripped as the plug goes in about half way good and tight. I’m torquing to 20 lbs. am I torquing to the right spec? Should I try teflon tape and the permatex sealant or gasket sealer? I’m completely flummoxed, please help!

Taylor,
I just went out and touched my front drain plug and it was wet.  No drips so far.  Is yours leaving a mark on the floor?


You shouldn't need much torque to get a good seal.  The fact you've tried all that's listed in your post makes me wonder if the leak is other than the threads.

I chased a rear leak in the transfer case (included taking off rear flange, changing seal and caulking the splines in the flange - 3 times!).  I then found the leak from one of the lower case bolts.  I had to clean all the oil off and blot with clean paper towels for a while until I could isolate where the oil was coming from.

It's awful close to the bottom of the cover.  A good cleaning and blotting over a period of time should pinpoint where it's leaking.  I can't imagine you have developed a crack at that location.


Also, how many wraps of Teflon tape?  Several is better than one or two.

[taylorpjones]

Thank you for your reply Rus. I may try more wraps of Teflon tape as you suggest and if that doesn’t work, maybe try and figure out where exactly the leak is coming from

[Bruce_W]

  “figure out where exactly the leak is coming from“
There ya go. Where it drips is not always the source of the leak. The drain plug is the bottom-most part of the axle. Oil from anywhere will drip from there. Sometimes it takes a tracker to find an oil leak.
BW

[taylorpjones]

Just so you guys know I have tracked it to somewhere right around the drain plug. I don’t see any cracks and the drain hole threads aren’t stripped. Maybe over time the hole has just wallowed out or there is a pinhole leak somewhere around the hole? I did get a new drain plug so that can’t be the problem I think. I’m going to try the multiple wraps of tape. Could I put gasket sealer over the tape? Don’t see why I couldn’t unless y’all know different! Thank you for your help!

[SteveKfl]

I'm just "guessing" as I've never tried it, but I would think the slick tape surface would not allow the "gasket sealer" to adhere to both surfaces to work right. I'd suggest cleaning real good the area around the plug and spray some white paint on it and watch where it comes from easier to see with contrast.  Or..., drain the oil, take off the cover and inspect from the inside for cracks or irregularities.  Clean it and JB Weld the flaw if not in the threads, or maybe you might even want to use it to fill worn thread surfaces.  They say it (I don't recommend the Quick Set) can be drilled or threaded when fully cured., or a new cover is in order???  Good Luck.

[OnlyOneDR]

Check your axle breather and make sure it is not plugged.  If the axle warms up and builds pressure inside the housing this might be the "weak link" in the seals and thus it leaks after you drive it since the axle seals, pinion seal, and diff cover may be sealed really well.

[taylorpjones]

Thanks to both of you. How do I check the breather or take it off?

[Chuck W.]

The breather is screwed into the cover, just above the fill plug, item #41 below.

I doubt this is your problem as if it were leaking, it would be very obvious. I suspect that you have a crack radiating out from the drain hole. A through cleaning and the use of a dye penetrant  test may show it.  Also keep in mind that the drain plug is pipe threads and pipe threads are tapered. Overtightening, especially with excessive wraps of teflon tape, can actually crack the housing.

[taylorpjones]

Thank you for all the responses! I did some research and ended up using a combo of Teflon tape and a little gasket sealer which appears to have worked. I was very mindful of not overtightening and used a torque wrench to about 20 pounds. I read that was right somewhere but can anyone confirm that?