Leaky Grease Fitting

[Ralph Pearce]

So I've got a fitting on the lower side of the differential housing near the rear drivers side wheel.  The leak is definitely coming from there, though I'm not sure if it's liquidized grease or differential fluid (comes out as fluid).  I did change the fitting, albeit a used on. Anyone with similar experiences?  Can anyone tell me more about this particular fitting?  Thanks for any and all assistance.

[JBNeal]

According to the service manual, originally that was a plug that would be temporarily replaced with a zerk for service only...my guess is that the zerk could be damaged and start leaking while the truck was in use, leading to premature axle bearing failure, among other things...from my experience, leaky grease fittings kinda fix themselves if'n enough dust collects around the leak point, acting like a coagulant

 

 

Edited August 27, 2021 by JBNeal
revised pictures

[Don Coatney]

Times like this the service manual can be your best friend.

 

[P15-D24]

Actually that should NOT be a zerk, but instead a bolt. Check http://p15-d24.com/page/p15d24/tech/tech_tips.html/ in the Rear Axle Lubrication

 
section.

[55 Fargo]

Put in a new zerk or correct bolt........... PS make sure your differential vent is open and not sticking or plugged too, that is another source of mitigating leaks..

[Ralph Pearce]

14 minutes ago, Rockwood said:

Put in a new zerk or correct bolt........... PS make sure your differential vent is open and not sticking or plugged too, that is another source of mitigating leaks..

Right, I made sure that was clear.

[DJ194950]

My repair manual says that temporary zerk fitting should be greased with wbg? Assume that to be wheel bearing grease? since that is to lube the inner wheel bearing for the axle Before the inner seal that keeps the 80-90wt. rear end oil from the brakes?

My repair manual does not seem to cover the inner axle seal and the purpose to seal out or in?

A just watched and old NCIS and Gibbs wrote a new rule- #55- "Sometimes I'm wrong".

Thinking  #55 fits my fit my thoughts?

DJ

[JBNeal]

The inner and outer seals make a compartment around the bearing to keep grease inside and everything else out...the inner seal and pinion seal make a compartment around the differential carrier to keep gear oil inside and everything else out...the difference between these 2 compartments is that the bearing compartment should be full of grease, whereas the differential compartment has gear oil up to a certain level with the gears (and axle and pinion shafts) slinging the oil to a certain extent through compartment air that may have moisture that can condense inside the compartment...the axle vent allows hot air and moisture out during operation, but can also let moisture and contaminants in if submerged...tread wisely

[desoto1939]

I have the same hole in the axle on my 39 Desoto. It is closed off with a threaded plug/ The plug is remove and then 1 oz of grease is plase on your finger tip and the grease is pushed into the back of the bearing.  They state to not sue a zerk fitting because then you will force under pressure too much grease intot he area and this will cause the grease to come out of the axile shaft and onto the brake linings.

You can use wheel bearing grease but push it in with your finger tip..

 

Rich Hartung

[PT81Jan]

Did you check if this eventually could be brake fluid that runs down from the wheel brake cylinder on the inside and finds it way (also) through the fitting? The color of the fluid and the paint that is gnawed away let me suppose that it might be. If you want to consider that as a possible source,  you could check the fluid level in the master cylinder first. (A second reliable method is to wear the new cloth you got from your wife some days before,  and observe the place on it where you got the fluid on while crawling under the car... If there appears a hole some ours later it is likely brake fluid... have some experience with method 2 ) 

Edited November 27, 2016 by PT81Jan

[Jerry Roberts]

I think Jan has got a good point , it probably is brake fluid . Does it feel thin like brake fluid or thick like gear oil ? If you put a drop on a painted surface the paint will wrinkle up and come off if it is brake fluid .  Also gear oil has a very strong smell all its own .  

Edited November 27, 2016 by Jerry Roberts

[JBNeal]

taking a better look at the original pic on my laptop, and it appears to me as well that there is a brake fluid leak on this wheel...I did not see the drip on the brake back plate or the streaks on the tire sidewalls, which are dead giveaways to me of a wheel cylinder leak of some kind...the lack of paint on the back plate around the bleeder screw is another indication of an ongoing brake fluid issue.  If there were gear oil leaking from the wheel bearing grease port, I would think the paint on the axle in that area would be stained darker, but maybe I am not seeing that in the pic.  Also, if the wheel bearing seals were leaking, there would be some indication where the axle flange meets the brake back plate.  Of course, the best way to verify is to check your fluid levels to see which one is lower

[PT81Jan]

In addition what I have commented with a wink, a really reliable thing is to put one drop of the fluid on the inside of the arms´ skin. Needs not hours until you have a leak inside as in clothes. Should start to tingle within a minute or so.
(Disclaimer / for safety reasons and if a child should read this: I do not recommend that, that`s just that what I had, when my brake cylinder was leaking).

Joking aside: Would be nice, if you post a feedback when you have detected what it is.

Ah and, that was (one of my) new clothing that I have used working on the truck. Today my wife was laughing, when writing the comment into this topic and I told her the truth ... haha

[DJ194950]

Wear that sweatshirt anywhere you please as battle scars with and old vehicle YOU maintain!

Anyone gives you looks? Tell them I fix my own vehicle, not pay someone else Big $$. Wear it with Pride!

DJ

[desoto1939]

On ‎11‎/‎26‎/‎2016 at 4:36 PM, Ralph Pearce said:

So I've got a fitting on the lower side of the differential housing near the rear drivers side wheel.  The leak is definitely coming from there, though I'm not sure if it's liquidized grease or differential fluid (comes out as fluid).  I did change the fitting, albeit a used on. Anyone with similar experiences?  Can anyone tell me more about this particular fitting?  Thanks for any and all assistance.

ralph: in the attached picture are you asking about the zerk fitting that is on the differential outside shaft just near the flange to the back of the brake backing plate or the  area on the bottom of the backing plate that has the rust area on which the paint has been removed. Some think you are referring to the rust area and I think you are talking about the specific zerk fitting  is on the axle shaft near the flange. If the zerk fitting then refer to the above discussion and how to grease the back of the bearing.

After looking at your picture I do see a drip of oil or some type of fluid that is just about ready to drip down onto the rim. And also on the rim and inside tires you can also see the same fluid.. You might have a leaky wheel cylinder and not a leak form the zerk fitting. I would suggest that you clean the area first and or remove the wheel and pull the drum to verify that the lower cylinder is not leaking.  Also noticed that the fluid is dripping down onto the inside lip and then running to the outside of the rim. If brake fluid is the paint bubbling up on the rim green paint. You might also have to replace the inner oil seal and this might be the cause of the issue but pulling the drum and wheel will only confirm the situation. 

 

Rich Hartung

Edited November 28, 2016 by desoto1939

[RobertKB]

To my mind, that is oil coming past the outer rear axle seal. The paint missing from the backing plate is likely from brake fluid but some time ago as it is well rusted at this point. Also, the paint on the rim should be starting to bubble or peel if it is brake fluid as it doesn't take long as I know from experience. I had to replace all the axle seals in my '53 Plymouth last year as the outer seal on one side had gone. Thought I'd do both at the same time. Differential oil was leaking past the inner seal, the bearing, the outer seal and down the inside of the backing plate. Just my to cents worth. I hope the original poster lets us know what he finds.

Edited November 28, 2016 by RobertKB

[TodFitch]

1 hour ago, RobertKB said:

To my mind, that is oil coming past the outer rear axle seal. The paint missing from the backing plate is likely from brake fluid but some time ago as it is well rusted at this point. Also, the paint on the rim should be starting to bubble or peel if it is brake fluid as it doesn't take long as I know from experience. I had to replace all the axle seals in my '53 Plymouth last year as the outer seal on one side had gone. Thought I'd do both at the same time. Differential oil was leaking past the inner seal, the bearing, the outer seal and down the inside of the backing plate. Just my to cents worth. I hope the original poster lets us know what he finds.

My opinion of the situation is the same as Robert's. This happened to me a couple of years ago and there was significant contamination of the brakes that had to be cleaned up in addition to fixing the leak. I do hope that Ralph pulls the drum and does an inspection. . .

Too bad I moved a year ago. . . Until the move I was close enough to San Jose to drop by and give a hand with this, including load of the drum puller and Ammco brake tool.

[Ralph Pearce]

3 hours ago, TodFitch said:

My opinion of the situation is the same as Robert's. This happened to me a couple of years ago and there was significant contamination of the brakes that had to be cleaned up in addition to fixing the leak. I do hope that Ralph pulls the drum and does an inspection. . .

Too bad I moved a year ago. . . Until the move I was close enough to San Jose to drop by and give a hand with this, including load of the drum puller and Ammco brake tool.

Yes, you guys appear to have deducted the situation exactly, differential oil leaking through the seals. The lost paint on the backing plate was from when we did the brakes and I haven't gotten around to repainting.  

So I guess the next step is to acquire new seals...

[Ralph Pearce]

Does anyone have the part number for the inner seals/recommendations on where to buy? I've got the outer seals National 5836 that I replaced when I did the brakes.  Also, I'm reading through threads/checking manual trying to get an idea of what I'll need to do to replace those inner seals...any advice appreciated

Edited November 28, 2016 by Ralph Pearce

[JBNeal]

Check for grooves on the axle shafts, this may be why the seals are not working... might be time for SKF sleeves

[Ralph Pearce]

So I've located the inner/outer seals. Does this pretty much describe the process for replacement?:

Remove the brake drum. Remove the four bolts holding the backing plate, then carefully lift the entire brake assembly past the axle end. Be very careful not to kink the brake line and use a hook or hanger to hang it above the rear axle. (this way you don't have to disconnect the brake line and re-bleed). Remove the shims (if any). You will need a slide hammer to get the axle and seals out. Attach the hammer to the nut on the end of the axle and give it a couple slaps and it will pop right out. Next put a hook on the slide hammer to remove the seals. Again a couple slaps of the hammer and the seals will come right out.  When you put it back together make sure you prelube the bearing and pack them as noted in the Tech section.

[Ralph Pearce]

2 hours ago, JBNeal said:

Check for grooves on the axle shafts, this may be why the seals are not working... might be time for SKF sleeves

I'd like to have everything ready when I do the job, but it appears that these sleeves need to be ordered. Does anyone have the size?

[Merle Coggins]

I don't think you'll be able to get the backing plate over the axle shaft without removing the brake line, unless you have a lot more extra line that I do.

Merle

[TodFitch]

17 minutes ago, Ralph Pearce said:

I'd like to have everything ready when I do the job, but it appears that these sleeves need to be ordered. Does anyone have the size?

The machine shop behind your local better auto supply should be able to measure and get the sleeves. You might want to check with Winchester Auto.

The inner seals are no longer available for my car, so I did not replace them. Other than that, the procedure is pretty similar so you can see my write up.

[Dave72dt]

Often in a seal spec book they will list the appropriate speedi sleeve along side the seal number