How bad is this rear diff?

[Wanted]

So I went to check out an '06 4x4 T1N Mercedes Sprinter 3500 416CDI today up in northern Europe. Overall, the van was in better condition than I expected, and much better than many others I have seen around the rust belt of northern Europe. However, there was something that really stuck out and was quite concerning to me. The rear diff was really rusty, much more rusty than the rest of the vehicle. I took a rust hammer to it and chipped some chunks of rust off to what felt like solid steel. I'm not sure how bad the rust on these can get before it becomes critical, and if critical, how expensive it would be to replace.

Other than that, there was a bit of surface rust on some of the rest of the vehicle but nothing that looked like chunks or flakes.


Another thing was on the side of the engine behind the alternator, there was an oil leak. It looked like it was coming from a tube going into the engine, and the dealer said it was from a tube, but I'm not entirely sure. I'll attach a photo of the leak here. What do you think?

 

[Bbasso]

I see plenty of rust in those pictures I'd say the axle was never coated/painted and shows... kinda looks inline with the rest of the rust I see...
Personally I'd get the wire wheel out (many of them) and get all that rust off everything and then prime, paint/protection.
If you were to purchase.

 

[luthj]

The oil leak is probably from the O-ring on the turbo oil return. Its a fairly easy fix. The leak (more like a seep) is pretty minor.

Overall the OM612 does not really leak much oil, the various seals are quite good. The few more common leak/seep points are easily remedied.

 

[Corneilius]

We just had a Ford in the shop with a rear diff about that rusty. We pulled it out and had it sand blasted because it was convent for us. When it came back the damage was less extensive than it had appear. No thin spots or any points of worry. In any case a new Semi-float dana 60 here can be had for pretty cheap compared to the overall price of a van. I assume Sprinter 4x4 diffs are more plentiful where you are. If the rest of the van is clean I wouldn't be worried.