Oil leak dripping down off of differential? Possible source?

Good morning. I'm currently battling with an oil leak, and I am curious of its possible source. The oil drips off of the edge of the differential (a555). I have tried the axle seals, since they looked wet, but the oil is still dripping. (After sitting a few days, the oil spot is about the sized of a soft ball.) I am curious what other sources for this drip could be. The return line for the turbo does not leak, nor does the rear main.
I haven't confirmed whether the input seal is leaking, speedo sensor, etc. are leaking. I'm just curious what other sources there could be for the leak. Any pointers would be appreciated. Thanks!

Cam seal?

The head on that side is dry. Ill double check tonight.

If any of the lines have been changed, the bolt that holds the turbo oil and coolant lines to the block runs through a big oil gallery. I can see oil weeping from it, following a hose back, then dripping. That bolt needs sealed. Also many of the intake/exhaust studs run through oil passages too, if they werent sealed either, it can cause a leak.

Another "forehead slapper" is a coolant leak pretending to be an oil leak,coming from the heater control valve, it can look nasty/dirty like oil and will drip right onto the trans and off the diff, picking up enough dirt and residual oil to camouflage its origin ... or not, but worth a look.

Mike

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Another "forehead slapper" is a coolant leak pretending to be an oil leak,coming from the heater control valve, it can look nasty/dirty like oil and will drip right onto the trans and off the diff, picking up enough dirt and residual oil to camouflage its origin ... or not, but worth a look.

Mike

If the differential cover has never been off the trans, it's unlikely that it is leaking. If it has been off, it's kinda tricky putting them together right so they don't leak.

Beyond the sources mentioned above, your two biggest culprits are usually the back edge of the valve cover (been there), and the manifold studs and bolts (done that). Other possible sources are the shifter selector shaft (seals are hard to find for that), the speed-distance sensor (doesn't usually leak unless the bolt backed out), turbo drain back hose (make sure the clamps are tight, but not so tight that they tear into the hose), and the PCV drain hose going to the airbox. Are you having to add oil to the transmission?

Your best bet is to check all the above mentioned sources, then power wash your engine bay as well as you can (especially the back side and bottom of the engine), and then check again.

A BIG +1 to the: inspect, CLEAN, and re-inspect in regards to finding mystery leaks. A reasonably clean engine bay make tracking the source of a leak(s) much easier, whereas a greasy mess can make it almost impossible.

Mike

I have good luck with the oil dye stuff.

Well, I looked in the dark tonight (I know, helpful . . .) and it looks like I need to move upward from the axle seal. I feel wetness around the speed sensor and around the tail shaft, so I think tomorrow I'll check the seal and bolt there. The diff has never been split (not leaking where it's glued together), and the side pan isn't leaking, etc. It is definitely trans fluid, as I recently changed my oil with royal purple, and whatever is leaking is brown, not purple (; The pan on the side isn't leaking, and since I rebuilt the engine about a year and change ago, the engine bay is relatively clean. -- No real build up of crap. Hopefully I'll find something out tomorrow morning.

Thanks for the suggestions, after a while battling the leak, it gets rather frustrating. (;