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Can you actually overfill the front differential? I've got a minor leak but I'm also fastidious about keeping the gear oil topped off before I drive the Pinz any sort of distance.

So is this a differential seal that has failed (and it's time to replace it) or is it possible that I've overfilled it in my zeal to keep it topped off?

Thanks in advance for the ensuing comments!

I assume you did fill the diff to the lower "plug" level!

If you do it the way they designed it to be done, it's not really possible to overfill it. There are three plugs on the diff, from bottom to top: a drain-plug, control-plug and a fill plug. You take both top plugs out and fill it until oil overflows out of the middle hole on the side, that's how you know it's at the correct oil level and it makes it impossible to over-fill it. If you are unsure whether you overfilled it, it leads me to believe that you didn't remove the middle plug while filling.

Here's where the verbal flogging begins. I know the drain plug and I thought there was only a filler plug so it didn't occur to me that there was a third plug! I have never noticed one. I guess I'll check that out this evening.

So there's a filler, another one to confirm the correct level and a drain....who knew? I thought there were only two!

actually 4 but who is counting.

actually 4 but who is counting

Someone knows there Pinny diffs

A bit of useless information pertinant to that comment, is that on the TD Pinnies they didn't fit the lifting hook in the top hole as in the 710/712, but rather just a standard filler plug..... I don't know why!

I can't wait to get under there tonight!

So there's the drain and a filler but also one (or perhaps two?) additional access ports for adding gear oil to the front differential?

Boy, just when you begin to feel like you are really familar with these things.....you ain't!

The top plug ( the one with the lift ring on the top surface) is actually an inspection hole.

Miles

So you do top it of from the access port on the passenger side of the differential. If i was overfilling it, it would be running out of that hole...right?

When it runs out of the hole, it is at the proper level.

I got to thinking about it, so I went out and looked at the front diff. Actually Miles was right and the top hole is just for inspection if you can find it, but it still works the same way. When I said three holes, I was thinking about the transmission and transfer case, but it's been a while since I did the diffs so I forgot they are a little different. Anyhow, when I looked at it I remembered that I was obviously filling it from the hole in the passenger side, but I know I fill it until it overflows. I can't remember for sure, but I believe I read it in the service manual somewhere, I can't recall.

Sorry for making things more confusing.

If i was overfilling it, it would be running out of that hole...right?

If it is running out of the proper hole...

There are two plugs on the side of the differential, but one is about halfway up and one is about 3/4 of the way up the side. They are NOT directly above/below each other but they are on the same side of the diff. The lower of the two is the "check" plug; this is the hole where oil should just start dripping out if the diff is filled properly. The plug higher up makes filling easier; as soon as the lower port starts dripping, stop filling and plug the lower hole. Remove the fill tube and plug the upper.

You're really _ucking with me now guys.

When I get home, I'll inspect the front differential, see how many drain / fill plugs I can find and see what's what down there.

what you will find is that the top and bottom of the diffs are identical pieces. the diffs actually have no orientation, that is to say they can be installed upside down or swap left for right. It really is that simple. The front diffs fill hole is somewhat more difficult to access then the others. The body support makes it a little tight to get at but not impossible. more than likely the very top (4th) hole has a lifting lug installed in it rather than a drain plug. the three you will be concerned with will have the traditional plugs in them with the drain one having a magnet (if it has not been changed out in its life)

David,
Here's a photo of the right front showing the 2 side plugs. You remove both and fill thru the upper one (behind the axle) until it runs out of the lower one (in front of the axle).
Hope this makes it clearer.
The one behind the axle is often covered with gunk and road dirt (like mine) so it's not obvious.

A picture is worth a thousand words, and prevents diff overfilling.