G'day all. I have a small leak on my transfer case, a few drops only.

My Car: GL320 CDI 2007 - just turned 10 and love it.
The car has the OFF-ROAD package on, so 2 speed Transfer case with lockable centre and back.
122.000 KM

I have notice the leak on the oil+filter change, not sure for how long it happened, no oil under car.

Troubleshooting so far:
1. Try to top up with MB236.12 a week or so ago. When open the top bolt it did like a coke bottle for about 3-4 seconds. The pressure was high as it start leaving the air out after only 2 turns... there was no need to top it up, it was actually above the hole. So I put the bolt back up.
2. checked wis and seems there is something on the top of the case, so I assume it's a there for this purpose (to let the air out).... Check it with the hand, it spins and moves free. Everything under the car is clean as, I leave in Sydney west - 60 KM from the sea, so the car doesn't get snow, too much salt breeze, maybe just a bit of rain from time to time; a lot of sun though.... not bragging...
3. order Liquid-Moli fluids for all; front diff, transfer case and rear diff to change them all...
Front Diff: LIQUI MOLY 85W90 Hypoid Gear Oil LS GL5 - 1.1L - Order 2 bottles
TC: LIQUI MOLY Top Tec ATF 1600 - 1.6L - Order 2 bottles
Rear Diff: LIQUI MOLY Top Tec ATF 1900 - 1.5L - Order 2 bottles
When I open the TC again to replace the oil, after a week, same thing again, under pressure. For last week wasn't leaking too much, I have seen only a drop, maybe from what was between the gearbox and transfer case.
Easy to replace the oil in them as in my case all have 2 bolts and the bottles come with a straw fitted under cap, so just drag the straw out of the bottle and squeeze the bottle in the diff/TC (no other tools required)...
Service details you can get from this post: https://mbworld.org/forums/gl-class-...our-fluid.html
4. Checked with local MB dealer: 120$AUD input shaft seal; about 8000$AUD for Recondition Transfer case; about 9500$AUD for new transfer case (but he never seen one as MB always replace with "Factory Reconditioned" in Germany); all this without labor.

So I'm seeking some advise: Is it ok for the TC to build up pressure? Has anyone seen/have this problem?

 

I don't think mine gushed out like that when I opened the fill plug, but then i dont have offroad package, isn't that the purpose of fill hole to keep it till there ??

 

Yes. Transfer case will build a bit if a pressure that is released when the fill bolt is loosened. However if you observe too much pressure and foaming your vent is clogged. This will result in excessive pressure that will push hard the seals and drip a bit. I have never seen a 2 speed tc for x164 (we do not have them here) and cannot advise about vent system (check valve or cane- shaped tubing terminating in the engine compartment), but that is something you should look into.

On oils- why different oils for front and rear diff? An off-road package requirement? Also why experiment with fluids and not use mb fluids? Just wondering.

 

ive seen two speed tcs in the states

 

Thanks for replays

MB dealer quote over 500$ AUD for the same type oils. So naturally paying over 110$ per litre of oil for the rear diff, I had looked around for different sources. End up buying Liqui-Moli as there were on special here and payed 177$ AUD for all. However, I'm planing changing them every time I do the gearbox oil and filter, about 50.000km.

The rear diff in X164 with off-road package is different from the front, it has the option to be locked for off-road use. Wis has listed like that, all different, I tried to find compatible version and Liqui-Moli was the only one to even suggest something to use. Wis has only one listed, MB235.15.

 

https://portland.craigslist.org/wsc/ctd/6175631465.html



Just in case anyone wants an off road package x164.