Rear Diff-Can't Stop Leak

[JRockwell]

Rear Diff-Can't Stop Leak-Leak Found-Right Through The Casting

Its been a long time, my truck has just been that good.

Anyhow, if anyone has any suggestions re: the following condition, I sure would appreciate it. It is driving me crazy.

2005 w/ 11.5 rear

Couple month ago, drips from rear end on driveway.
I needed to change the fluid anyway. So I pull the factory cover and replace the fluid and torque to forum relayed specs. I cleaned both matting surfaces and removed the "cancer" from the rear end housing (like an 1/8" to 1/4" of the exterior of the housing is flaking off). I reused the gasket.

1 week later, drips. I remove the cover, save the fluid, buy new "re-useable" gasket and put all back together using proper torque.

1 week later, drips. I re-torque all the cover bolts to higher than recommended on this forum, but not so much to snap them off.

1 week later, drips. I order a mag-hytech. It comes in, I drain, install mag-hytech.

1 week later, drips. What in the heck is going on? The mating surface on the rear end not planed properly? Perhaps that outer 1/4" of housing was holding the fluid back and the "inner" metal is not machined properly? I don't know.

Losing all that metal off the rear end worried me a bit. Should I try re-torqueing the mag-hytech bolts to a higher amount, or drop the fluid, pull the cover, ditch the o-ring and rtv the cover on with a good amount of bead?

It has really ticked me off. Any help would be appreciated.

 

[brods]

Make sure the vent line is clear and not plugged. Is it leaking at the pinion seal, running down the pumpkin and dripping off at the cover?

Big chunks of the casting have come off mine as well. Worst case is there is porosity in your casting that a chunk was blocking. I would think a good cleaning and some sealer would stop a porosity leak. Depending on the condition of the casting and the location (ie wall thickness) you could try carefully peening it closed.

 

[JRockwell]

vent is clear
definitely not leaking from the pinion seal
tell me more about porosity. that is scaring me a bit. if its not the mating surfaces, it could be seeping through the metal housing? Is that a structural issue?

I appreciate you feedback.

 

[brods]

It is typically not a structural issue. We see it in pump castings from time to time. Small pores in the casting that allow minute leakage. Often peening the area with hammer will close the pore(s) and stop the weeping. Unless the area in question was super degraded from corrosion I would not hesitate to try peening the pumpkin on my truck if there was a leak from porosity.

I wouldn't worry about it until you are sure what the problem is. Most likely its corrosion of the sealing surface or the surface got gouged when being cleaned. Like any repair, determine the actual problem before throwing parts at it.

 

[JRockwell]

a neighbor recommended that I use brake clean and wash all the oil off the bottom and dry it. Then watch the bottom to see if its coming from the matting surface or if it is seeping through the metal. he was a mechanic for Exxon and could not believe the thickness of the rust coming off the housing like brods he said it could be a pin hole with that much material coming off, or it could be a hairline crack on the matting surface.

Anyone else dealing with this?

 

[brods]

Rust, yes. Leaking, thankfully not yet. I was knocking the rot off with a chipping hammer and decided to stop before it started leaking.

Why does this new forum software flip the photos???

 

[JRockwell]

mines worse then that. thanks for helping me out brods.

 

[JRockwell]

well, I cleaned and sprayed with brake cleaner. It is literally seeping through the pumpkin. I wipe and a bead comes out. Its on the front side of the pumpkin on the passenger side half. if that makes sense. Not on the portion where the pinion exits, but on the rounded pumpkin face. Can I weld the thing closed? How can I measure the wall thickness of the metal there?

 

[JRockwell]

I'll attempt to upload a picture of the now known issue.

 

[JRockwell]

Anyone know if these 11.5 axles are cast iron or cast steel?

My next step will be to clean, sand the leaking area to determine if there is a crack or a pin hole from a bad casting or if the entire local area to the leak is paper thin.

Praying for a pin hole. Considering drilling and tapping and screwing in a very short bolt loaded with rtv. Any other opinions on this matter?

 

[MarkEagleUSA]

Praying for a pin hole. Considering drilling and tapping and screwing in a very short bolt loaded with rtv. Any other opinions on this matter?

Try some of that FlexSeal that's hawked on TV?

 

[garyp285]

That is some bad rust, and if it were mine I'd be looking for a complete rear end at a pull a part.

 

[JRockwell]

Oh boy, thx.

 

[JRockwell]

It almost seems like there are two castings. An initial and then a 1/4" material cast on top. The "cancer" is uniform 1/4". Once chipped, beaten, or it falls off, the underlying metal seems very competent. It seems to be all or nothing. 1/4" ready to come off, or nothing coming off, and always down to a smooth uniform "undercasting".

 

[User113]

Sounds to me like a bad casting if it's parting/peeling like that. I would definitely look into a donor axle rather than trying to fix it. But that's just me.

Did you try peening it as brods suggested? Or cleaning the inside well and putting a thin, even coat of RTV sealant might work. Easier and cheaper than drilling or welding.

 

[JRockwell]

How do you "peen" the casting? Just turn over the affected area from the outside? I'm not sure I can access it from the inside. The leak is 1/3 up the housing on the front side, passenger side. I think the ring gear will be in the way, but I won't know until I drain and pull the cover. If i can locate the area from inside, I'll brake clean it real good and give that a try. Then goop it up on the outside. That's one option I'm contemplating. I really need to sand it down and verify that it is a pin hole and not a "thin area". My father called my uncle who was a mechanic his whole career for Texas eastern transmission company and he said that he has fixed both pin hole and cracks in differentials over the decades. Very infrequently, but he said it can happen. If it's a pin hole he said that he has drilled the hole, tapped it and installed a plug. If cracked, drill a hole on both ends of the crack and then had a very talented welder brake the case. Of course brazing would require I pull the rear end off the truck. I'm really in a tough spot trying to make a decision on which way to go.

 

[mweiman]

I think if you could drain and remove the rear cover and clean everything up real good and dry it you could use a two part epoxy inside and out. Would probably be better than trying to weld it or RTV.. Permatex makes a 5 minute epoxy that sets up clear that I have used.

 

[JRockwell]

I really appreciate everyone help. Thank you.

 

[LFalconer]

To me, if you tow heavy and load the truck to capacity, I would be in market for new axle housing. Also how long do you plan to keep the truck? That is significant rust, and will likely continue to worsen. Years ago I had a 2001 Ford SD with 7.3. Oil pan rust. Used POR 15 to mitigate, however the oil pan is not a structural component per se, the rear axle is. Good Luck

.Luke

 

[BigPapa]

Peening would be taking a hammer, preferably a ball peen, and forcefully tapping the metal where the leak is, basically "mashing" the hole in the metal together to seal it.