DIY Transfer case replacement on ML320
 

Hi there, my first post to a great forum! Unfortunatley the topic is not so great: how easy is it to replace the transfer case in a 99 ML320? I'm a reasonably competant home mechanic. Are there any things to particularly look out for?

My ML320 is a 99, with 80,000 miles. It's been making a ratcheting noise from the transfer case, noticeable when first moving off. The local dealer diagnosed it as a transfer case problem, but I balked at the $4500 cost! The noise hasn't increased in intensity for a few months so I'm not sure how much time it's got left.

Any and all feedback much appreciated!

TIA

I don’t think it would be that difficult from looking at the transfer case and the way it’s fitted in the vehicle, but I’ve not replace mine so I’m not sure.

I had to do some exhaust system work and I removed the support that holds the transfer case to the vehicle, there were like 6 easily accessible bolts to remove and then I think you would only need to remove the drive shafts to drop the unit. I don’t know if the driver’s side torsion bar needs to come out or not to remove the transfer case, I’m thinking it does not, if it does there are some instructions in one of the threads on this site how to do that.

If you're pretty mechanical I'll bet you can do it.

Do a search on the forum here, someone did this about 6mo or a year ago and I think they even had some pictures. Also, your dealer is way out to lunch. $4500 I'd believe for a transmission, not a xfr case. My transfer case was replaced under warranty at 45K miles due to the 98-99 year problem with the truck shuddering on tight turns due to the xfr case binding. Cost was amazingly (to me anyway) only $1300 ($1000 for the case and $300 labor (about 3hr job)).

I thought $4500 was a bit much as well - the S.F. dealer wanted $3100 for the case alone + 4-5 hrs labor! I called some other dealers in the area and they wanted about $2150 for the part so maybe the S.F. one includes the dealer's boat payment.
I have searched the forum and found some info on replacement. Now I just need to get down to work!

OK - replaced the transfer case - yeah!

It was not too bad a job, although a lot slower than I thought. Here are the steps I took, together with things I would do differently next time (there better not be a next time, with this truck anyway!):

1. Remove the cross member support - (8) 5/8" bolts. The case then drops down slightly which helps access. Remove the 2 studs from the bottom of the case at this time to avoid potential damage to the studs if things get out of hand - the new case doesn't come with the studs.
2. Disconnect the electrical connector and unclip a cable going into the transmission.
3. Disconnect front and rear driveshafts and completely remove the front driveshaft. First remove the (6mm) allen bolts securing the rubber couplings on both the front and rear driveshafts; now rotate the front shaft to get a wrench on the (4) 5/8" bolts holding the front driveshaft to the transfer case output shaft. It might be better to undo the driveshaft rubber couplings before removing the cross member as they then wouldn't be angled down so much. (This is all probably a lot easier with a proper lift; I had the front wheels on ramps and the rear on the driveway, so couldn't rotate the wheels, and hence the shafts, to gain access to the bolts).
3. Undo the 5/16" bolts holding the transfer case to the transmission. These are hard to access at the top, but doable (I just used a small ring spanner (wrench). I couldn't get a socket on them, even with a universal coupling.
4. Use a jack to help take the case down (and back into place), but (as others have stated!) you NEED a buddy to help you ease it into position while it's balanced on the jack, operate the jack and give words of advice as you decide whether to risk damage to the case or your left arm as the case slips off the jack.
5. Once the case is out, transfer the breather tube and fittings to the new case. I tried to disconnect this before removing the case and managed to break the plastic fitting that plugs into the case; duct tape is now holding things until I can get a new fitting.
6. When installing the new case, angle the rear of it upwards to clear the exhaust system and then level it out to mate with the transmission.
7. Use blue permatex threadlocker on all the bolts. I used it on the allen bolts as well, although there appeared to be a green substance originally on them - hope it's Ok.

It all seems fine now, no clicking. I may have to adjust the transmission linkage though, as sometimes it will not come cleanly out of Park. Maybe the removal of the cross member and the slight dropping of the transmission caused this? Not sure how to adjust it yet - need to comb the archives...

Glad to hear that changing the transfer case is a DIY for those of use who are somewhat mechanically inclined.

I had to remove that cross member when I did some exhaust system work. I did support the transfer case with a jackstand but I would not think removing that support would have anything to do with it being hard to get in and out of park.

This morning I had no trouble getting out of park, so maybe it was just me being too tired to drive properly yesterday! I recently had an engine replaced on another car, and afterwards the shift linkage was out of whack, even though they hadn't removed the transmission (in spite of the workshop manual saying they needed to remove the engine and trans. together and then split them. Still in dispute with the repair shop on that one!).

Hmmm... Been thinking about buying the ML, but reading about the transfer-case problems are a little scary. My current SUV is an '89 with over 180k miles, and I have never had the first hint of a problem with the transfer/transmission/engine or anything nearly that serious. Just the normal problems with the water pump and some electrical stuff.

So, please tell me that the ML320 is not prone to drivetrain problems. Between this and what I've read about Chrysler products lately, I'm beginning to have second thoughts.

I think the transfer cases did have problems and they upgraded them several time apparently. Perhaps some other, more knowledgeable members can give some history here. I actually thought about appealing to MBZ for some help in covering the costs as it shouldn't fail that quickly, but not sure if I can deal with the bureaucracy. Apart from that though, the rest of the drivetrain seems really solid, it's mainly annoyances like the fuel gauge, machine gun locks, etc. (in my case anyway).