Rear End Leak
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Rear End Leak
I spent a couple of hours cleaning the years of gunk off of the rear end a couple of days ago and looked under the truck last night to see this...
It looks like it is leaking out of the weld and the top rear of the diff...
Here is the other side...
Would a guy just weld that spot to keep it from leaking further? Have you seen a leak like this before?
I have read on this site that the fluid level in the diff is full when it starts to leak out of the access plug. I am going to re-torque the bolts on the other side as well.
It looks like it is leaking out of the weld and the top rear of the diff...
Here is the other side...
Would a guy just weld that spot to keep it from leaking further? Have you seen a leak like this before?
I have read on this site that the fluid level in the diff is full when it starts to leak out of the access plug. I am going to re-torque the bolts on the other side as well.
Hotshot
Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
Yes, the full level is at the bottom of the fill hole. The front pinion support uses an o-ring for a seal, it also has adjustment shims so if you take the pinion out to replace the o-ring, be sure to put the same shims back in.
As for the leaking weld. You could weld it or maybe try something like JB Weld or something similar.
As for the leaking weld. You could weld it or maybe try something like JB Weld or something similar.
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I assume you are talking about the pinion retainer o-ring in this diagram?
If I drop the driveshaft, etc and replace the pinion support O ring, I assume that will also cause a majority of the fluid in the diff to leak out? Maybe get me closer to a complete fluid change in the rear end?
I haven't ever torn one apart before.
If I drop the driveshaft, etc and replace the pinion support O ring, I assume that will also cause a majority of the fluid in the diff to leak out? Maybe get me closer to a complete fluid change in the rear end?
I haven't ever torn one apart before.
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
I assume you are talking about the pinion retainer o-ring in this diagram?
If I drop the driveshaft, etc and replace the pinion support O ring, I assume that will also cause a majority of the fluid in the diff to leak out? Maybe get me closer to a complete fluid change in the rear end?
I haven't ever torn one apart before.
If I drop the driveshaft, etc and replace the pinion support O ring, I assume that will also cause a majority of the fluid in the diff to leak out? Maybe get me closer to a complete fluid change in the rear end?
I haven't ever torn one apart before.
Don't be afraid of the Ford 9". It's probably one of the easiest rear ends to work on.
Postmaster
Joined: Nov 2011
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First thing to check! If it is holding pressure inside the rear it will leak. Remove the vent from the axle tube and check that the hole is clear and cap loose and clean. Some wire and brakeclean or parts washer will fix it if needed. Repop vents are available also.
If it still leaks, I would fix the weld with JB weld. Clean thoroughly... brake clean and wire wheel and more brakeclean then apply JB weld to the area. This repair should last as long as the rest of the rear.
If it still leaks, I would fix the weld with JB weld. Clean thoroughly... brake clean and wire wheel and more brakeclean then apply JB weld to the area. This repair should last as long as the rest of the rear.
FTE Legend
Joined: Sep 2003
Posts: 54,078
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From: NY and VA
I almost think Ford had a TSB on leaky welds when I worked at a dealership. If CRS isn't involved , the guys in the body shop re-welded quite a few.
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Hotshot
Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
Good point that I overlooked! The axle vent looks like it's big but once you take it off, you'll see the actual vent hole is pretty small and it will plug up easily.
The vent is also the hold down for the rear brake hose to axle housing. In the picture the vent is the piece that has the vent line with the green hose clamp on it.
The vent is also the hold down for the rear brake hose to axle housing. In the picture the vent is the piece that has the vent line with the green hose clamp on it.
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Thanks for the responses. I am going to check the vent and try the JB Weld for sure. Once I have those squared away and the fluid level topped off, I will try to retorque the bolts on the other side. If I still have a leak, I will tackle replacing that o-ring.
I'll keep you posted with what I find out.
Thanks again!
I'll keep you posted with what I find out.
Thanks again!
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Freshman User
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Excellent call on the vent hose 
It was plugged with spiderweb/eggs...
Cleaned out the line and the connection on the axle itself. Mixed up a little JB weld to fix the leak and added about 1/5th of a new jug 80w90 gear oil.
Now I am on the hunt to figure out what the tag on the rear end is telling me. I am pretty sure I saw a decoder in the LMC parts book on-line.
It was plugged with spiderweb/eggs...
Cleaned out the line and the connection on the axle itself. Mixed up a little JB weld to fix the leak and added about 1/5th of a new jug 80w90 gear oil.
Now I am on the hunt to figure out what the tag on the rear end is telling me. I am pretty sure I saw a decoder in the LMC parts book on-line.
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The tag reads...
WDM CJ 9EA
2 75 9 356A
I found the following on the Fordification Site...
WDM-CJ = Ford F100, F150 Pickup '79
2 75 = 2.75 Gear Ratio
9 = 9 inch ring gear
Non-locker
9EA = 1979 May 1st
Not sure what the 356A means...
WDM CJ 9EA
2 75 9 356A
I found the following on the Fordification Site...
WDM-CJ = Ford F100, F150 Pickup '79
2 75 = 2.75 Gear Ratio
9 = 9 inch ring gear
Non-locker
9EA = 1979 May 1st
Not sure what the 356A means...
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
'79 / 2 75 = 2.75 Gear Ratio / 9 = 9 inch ring gear 2 75 decodes to 2.75-1 non locking (no Limited Slip). 2L75 decodes to Traction-Lok (Limited Slip).
9EA = Assembled the first week (A) of May (E), 1979 (9).
356 = Assembly Plant code / A = initial design, B would be 2nd design, C the 3rd and etc.
Lead Driver
Joined: Nov 2006
Posts: 5,217
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From: Pa.
Excellent call on the vent hose It was plugged with spiderweb/eggs...
It was plugged with spiderweb/eggs...
BTW really sweet truck and set up .. Something you might think about when or if you are going to rebuild the C6 trans .. A built C4 would give you back 30-35 Hp but a drive shaft change would be needed also I believe .. It all depends what your using the truck for I guessA good thread on auto trannys
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 787
From: Simi Valley, CA
These charts were taken from the awful Red Book, a POS originally written/published by and foisted on mankind in the early 1970's by two clueless clucks who were members of the Fabulous 50's Ford Club.
It's been updated several times since, the two clucks have since sold the publishing rights to another clueless cluck. Most of the info is mis-leading or WRONG!
FoMoCo: The WDM-CJ portion of the rear AXLE ID tag only decodes to this:
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