I would first like to thank you all for your insightfull Q&A sessions.I have been a reader of this forum for six months and have appreciated the help I've recieved since the purchase of my G. Now I have a few questions of my own.
With the buying of any twenty plus year old vehicle I knew there would be some work in my future. After finding a few leaks I proceded to start by replacing the cam seal at the front. I now would like to proceed to the oil pan and finish with, what I think is a speed actuator fitting at the back of the transfer case which also leaks.
I would like to know if I'll need to remove the harmonic balancer or if there will be any other large obstacles in my way when it comes to the pan? And will the large balance wheel along with the rear shaft need to be removed to get to the actuator? Any useful advice or experince would be greatly appreciated. Thanx in advance and keep it up.
resealing the oil pan is easy - but it rarely ever leaks. If so, tightening of the bolts will most likely do.
Usually its the rear crank seal that starts leaking and that will be a lot of work.
I am not sure what you have in mind when talking about the "actuator"
Harold,
I think its only the pan since oil is dripping from the seams up front and along the sides.
And the piece I was trying to describe is on the backside of the transfer case next to the drive shaft. I thought it had something to do with the speedometer.
you are absolutely right - the back side of the transfer case has the rear output shaft and the speedometer drive. If has an easy to replace gasket. However, you will have to remove the driveshaft and the balancer to work on it. Make sure you mark the position of the balancer and driveshaft - otherwise you will have horrible vibrations.
Strongly recommend to follow the manaul since you might encounter other problems when opening the speedometer drive.
I don't know about the diesel. That damper on the rear driveshaft might cause problems. But on my 280GE the speedometer drive can be removed without touching the driveshaft. You can look for yourself though and see if you can get past the damper.
In order to remove the speedo drive you need only disconnect the speedometer cable, remove the four bolts (I don't remember if they're 8 or 10mm heads) that hold it to the transfer case, and withdraw the unit straight back about 20mm to disengage the shaft. There aren't any fiddly parts. If the shaft/gear at the center of the drive falls out while you're removing it, just clean everything up good and push it back in before replacing the unit.
I've pulled these off of 4 or 5 t-cases and never found a gasket under one of them....nor in any other part of the transfer case for that matter. They're all sealed with a liquid sealant. There is an MB part number for the sealant, but on the speedo drives I've been using "Hylomar HPF" from Permatex brand, available at most big auto parts chains now. It's a non-hardening flange sealant that is oil resistant and even seals through oil so the surfaces need not be perfectly clean.
It's easiest to do this job at the same time you're replacing your diff fluid, since there is an oiling port to the speedo drive that is below the standard oil level so that if you remove the speedo drive with the t-case full of oil, oil will weep out that hole until you put the drive back. If you do the re-seal during a fluid change, you can do it while the t-case is empty and avoid the leakage. The last time I changed a speedo drive I was in a hurry so I just coated the drive body sealing edge with Hylomar ahead of time, pulled the old drive body, and held my finger over the oil hole while I wiped the back of the t-case clean, and then quickly popped the new speedo drive into place. A little oil leaked while I was placing the cover, but the Hylomar sealed it all up okay.
Sorry to ramble so much. If you're unlucky and it looks like the damper will prevent you from pulling the speedo drive body straight back 20mm, then just remove the rear DS and the damper from the t-case output flange, marking them in place first as Harald said. It should really be only about an hour job from start to finish, and the biggest part of the time will be spent on all those drive shaft nuts. Best to use new nuts when putting the drive shaft back on too, though I've re-used old ones with no problems before.
Just in case you have not checked it directly, the cam cover on the older diesels, tends to leak just enough to make it look like black oil is coming out of every possible place. It will leak at the very back of the cover. Replacing the gasket will help for a while, but the real fix is to removed the cover, clean it thoroughly, the examine the area inside and around the lip. I have owned three of these engines, two turbo and one not, but all three leaked. A central American mechanic showed me how to check and grind the slight rise that causes the leak. Find a mechanic over 50, with a name like Crusty or Bud, who knows Mercedes engines. He will know what to do. Very small operation.
As Harald notes, the rear main can leak, although I have never had one fail. But, when it is bad enough it is a big job. If you have a clutch-manual transmission, this becomes more necessary to fix as the clutch is not noted for its ability to operate as an "oil bath" clutch. You can also check for leakage if you have a clutch, by opening the bolt drain at the very bottom of the bell-housing. If a lot of black diesel engine oil runs out, your rear main seal is toast. I doubt if the auto transmission has this feature - since it is a G only feature, and I have never looked at an auto transmission G. Early synthenic oils seem to leak more than regular oil, although I have read lately that even synethic oils now have additives to slow cohesive capillary action...escape. So, if your G rear main is leaking a little, you might try a little heavier oil. I tend to run 15-40 or 50, although the climiate here is mild and I have a building and blockheater for my G.
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