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How in the world - Front Dif.

drewbsking

NAXJA Forum User
Location
Detroit, MI
Got my hub assemblies and wheel joints (Front Axle U-joints) fixed (I farmed it out to a local shop). WOW, what a difference, no more noise. Thought they might have ruined the axle seals because I saw oil all over the bottom axle yoke.

To make sure it was not just some left over oil from when the axle point was taken out to work on the u joints I took it to the local quater car was to wash it down. I will keep an eye on it, if i see it happen again i for sure have a leaky axle seal.

THIS IS THE KICKER, I wanted to make sure I had the proper amount of Differential Oil in the Case so I took off the plug and a TON of oil gushed out (Good thing I had a rag and cardboard because I would have made a huge mess). How in the world can the Front Diff be overfilled? I thought the oil should be just at the bottom of the hole. Furthermore, the XJ was on a slight incline so I thought it would be less likely to flow out of the plug hole.

Any insite on why how there was so much oil in the front differential?
 
it can be overfilled if the filled it from the vent hose on the back side of the diff. It sits alot higher then the fill hole..
 
My ignorance will now show. I know there is a vent tube for the rear diff. (it makes a mess of the unibody) It makes sense that the front also would have one but where the heck is it?! I know its on the rear of the diff. I will look harder.
 
Ok just went out and looked it on the upper left. SO... someone would have had to take that tube off right? Because were does it go? ( it had the head shield wrapped around it.)
 
I was a little posting happy, sorry guys. Looking a little further I found that it tie to the electrical near the firewall under the hood. I can see how one would use this vent hose if they didnt have a pump. They must have overfilled.

I am amateur mechanic, I also farm out the changing of the differential fluid because I prefer to take the cover off rather than just pumping it out and putting it back in. I dont want to make a mess of my garage. I see in my case the so called professionals did it the wrong way.

Does the oil foam similar to engine oil if over filled?
 
depends on how much it was overfilled... your probably fine, extra oil = extra cooling.

i wouldnt say the professionals did it the wrong way,but if your gonna make a scene, do it yourself then.
 
Also possible: was the axle hot when you pulled the plug? heat = thining = higher volume.
 
Not meaning to hi-jack, but shouldn't the seals be able to handle some extra fluid?

I recently had a tech reseal a long-time persistant slow leak in my current D30.
It started leaking again within about a week, noticed it while workin' out-of-state.

It leaked so much, I felt I needed to check the fluid level before my return trip home.
When I pulled the fill-plug, same situation: a substantial amount of fluid ran out the fill-
hole even though it appeared to have been leaking considerably (checked on level ground).

Took it back, then stood in with the tech as he repulled and resealed everything back up.
When it was time to fill the diff, he filled it until it started running out, then gave the pump
several good hard cranks, forcing a lot of extra fluid in... then quickly replaced the fill-plug.

Vent appears to be fine: hose attached and clear...

A week later it's leaking again... & this is a reputable shop that has helped me in the past.
(the axle shaft is in much better shape than many the tech has seen that would not seal)

When home, my XJ is usually parked on a slope with the passenger (leaking) side down hill.
.
 
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Funny thing is that the owners manual says that the fluid should be 1/2 from bottom of hole. However, the FSM says bottom of the fill hole. ALSO, the FSM says loss of lubricant can be cased by to much oil. Page 3-19

More info on leaks....

Loss of lubricant can be from worn axle shaft seals, cracked differential hosing, worn pinion seal, worn/scored yoke, Axle cover not properly seated (duh).

ALSO, it says a 1/4 in bead of RTV (some youtube videos show people spreading it our with fingers which seems wrong.
 
It's possible the diff was filled while on a rack, with the axle at fool-droop. Quite possibly, this would cause the front axle to rotate to the rear, raising the fill plug. Then, sitting on its wheels, the axle rotates back to neutral position, resulting in the diff fluid being "over filled".
 
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