8n differential leak

slcullen · Dec 6, 2013

Season's greeting ladies and gentlemen. My 8N has a two inch
hairline crack in the bottom of differential case and is leaking
excessively. It's not pouring, but much more than I want on the
shop floor. At first I thought it was the PTO seal, but cleaning it
up has revealed the hairline crack. It begins right were the
differential case bolts to the axle housing.

After scratching my head about fixes, it seemed to be three
choices: J B Weld as the easiest, after draining the hydraulic fluid,
and cleaning the surface; getting the crack brazed,; and lastly,
swapping the rear end out of another 8n, to which I have access.

So I decided to take the easiest rout first, the J B Weld. After
applying it and letting it cure for 24 hours under a 60-watt bulb,
I refilled the fluid chamber and let it sit overnight. No leaks, so I
fired it up and drove it around, after going through about 20
cycles of the lift arm. Every thing seems to be OK and so far no
leaks. Any thought on how long this “repair” is going to last or
suggestions for a more lasting repair? Thank, Spencer in
Tallahassee

Mike OH · Dec 6, 2013

Can't tell you how long it will last. It likely depends on how much stress it sees. I do think you took the right steps in fixing it. Can alway get it brazed later if it leaks agian, and don't get rid of that other rear end you have access to. That alone will insure the JB repair will hold. Good luck and welcome to the board.

old · Dec 6, 2013

Taking an educated guess not long since once a crack has started it will keep on cracking and it being cast it is even more likely to crack more. Plus depending on where the crack is and all one day you might be driving it then all at once you might be sitting a whole lot lower when it lets go

souNdguy · Dec 6, 2013

personally?

i'd drian it, drillstop te crack and weld with a cast iron type rod.. preheating local area with propane torch.. especially burning oil ot of the crack.

then peen it while slow cooling and still applying some propane heat.

that , if done correctly will be stronger than brazing, and leak proof.

repalcement would be my next choice.

while not often.. I have done some cast welding.. so far.. ( knock-knock ) with good results.

including an Noil pan, and a 3pt pin boss on a rowcrop and a cast loader bracket.

so far.. all holding under weight and regular use.. not being babied...

best of luck.. jb may stop the leak for now.. but that crack will run and flex and that jb will be a temp at best fix...

russb wa · Dec 6, 2013

A crack separates the metal into two pieces, one on each side of the crack. If load/stress is uneven, force is focused at the end of the crack. This is because that is where the two pieces are joined, adjoining the unequal forces.

Good practice for crack repair is to drill the end of the crack. This will spread the stress to the radius of the drilled hole.

It may be difficult to drill at the exact spot where the crack ends. Maybe drill just past the end of the crack to make sure. The idea is to not leave part of the crack on the other side of the hole. Then JB any sort of close fitting plug to fill the hole. IMHO

nebken · Dec 6, 2013

I have a 9n I bought in 1999. It has a crack in the rear end housing on the bottom from the drain plug to the left axle housing. it was that way when I bought it. Didn't know it was there till I replace the PTO seal. It has been brazed on the outside and on the inside of the housing is some kind of thick red expoxy.

It doesn't leak yet!

Colin King · Dec 6, 2013

I think your repair is in the right direction. If your tractor sees little use, keep it as is.

But if you plan to use your N much, I would suggest following Soundguy's suggestions. The damage you describe is in a higher stress (i.e., greater load) area, and a strong repair will be needed if you plan to work the tractor.

The JB weld repair does no harm and may work well for you. If you find that it is not holding up to repeated use, then make a more thorough repair.

Good luck!

Colin, MN

Dean · Dec 6, 2013

It will not hold up long term.

Keep the spare differential housing.

Dean

L.B, · Dec 6, 2013

If I lived in TN where the winter is not harsh and could get it inside I would put the new diffy on it. I would take the old diffy, stop drill the crack an braze it. Problem fixed and still have a 2nd diffy.

slcullen · Dec 11, 2013

Thanks for all the help gentlemen. I"ve gone the J B Weld route and so far so good. I hesitated to drill a stop hole. Are the chances high of getting metal shavings from the drill bit into the hydraulic fluid? Merry Christmas to one and all!

8n differential leak

slcullen

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Mike OH

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