Over-Filling Rear Diff

[Dagwood]

Is over-filling the rear differential a concern? As a creature of habit, I have always filled the rear differential until the oil starts to drip out. The capacity for my rear differential is listed at 6.5 pints. I think I squeezed in 4 quarts. Oops. Should I extract the extra or just forget about it?

 

[Pablo]

Dripping out is one thing. 1.5 pints over might be another. In some diff's it's not a huge issue, other it will put fluid pressure on the seals. I would drain a bit....via the fill hole.

 

[Gurkha]

Excess oil will also add resistance to the gears and cause heat as well as wear the gears down, not to mention busted seals.

 

[Dagwood]

Guess I should pump out a bit then.

Thanks

 

[Dagwood]

Just to clarify, I filled the differential up to the fill hole. I did not force an extra pint in and then slam on the fill plug. If you discount the amount of oil that was remaining in the quart bottles, I am guessing there is one extra pint in the diff.

 

[Kestas]

Then it looks like you're okay and it was filled properly.

 

[Dagwood]

Maybe I am getting to anal about the whole thing. If I had taken the vehicle to any lube shop they would have probably done it the same way. (filled it to the bottom of the fill hole) I looked at the fluid capacity printed in my owners manual after the fact and realized that I used a bit more then it stated. I also spilled a bit while I was filling it, so I guess I am OK. I'll shut up now.

 

[Kestas]

Plus clingage loss from the bottles.

 

[unDummy]

Is the rearend vented? If so, don't worry about it.
And, as long as you filled to the fill hole, don't worry about it. There are manuals that are incorrect.

 

[JTK]

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Is the rearend vented? If so, don't worry about it.

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I agree. If the vent is doing what is should and you are WAY overfull, gear oil will just blow out of the vent hose/sparger.

Joel

 

[BGK]

I don't think there is a diff that can be easily overfilled. Don't the fill holes always indicate full when fluid starts to drip out?

 

[Pablo]

Some diffs are to be filled below fill hole, as an example. Some GM's say:

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Fill to 3/8 in/9.5 mm below fill plug hole.

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The will leak at the seals if overfilled and they have a vent.

 

[JTK]

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I don't think there is a diff that can be easily overfilled. Don't the fill holes always indicate full when fluid starts to drip out?

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Heheh.. You'd need some special skills or a car flipped on it's side to fill a diff to the top! Only time I've ever seen an axle seal, input seal or diff cover gasket leak, it was either a plugged vent line or an old battered seal.

Joel