maxusa

How-to Rebuild Mercedes ITC Transfer Case: Part 1 of 3

I am an automotive enthusiast, and enjoy working on cars while often saving money. Over the years, I have been going progressively deeper into complex maintenance as my cars age (with me). My 2010 X164 with 45K miles started leaking fluid, and I took the car to the dealer. They diagnosed a leaking input seal of the transfer case. I declined their quote for $1,200 and decided to tackle the job myself.

I started with research on this and other forums, purchased replacement parts and additional tools. I found that most articles talk about the Integrated Transfer Case (ITC) removal and/or stretched chain problems. No article walks someone D-I-Y style to rebuild end-to-end; that is from removal to installation using basic tools in a typical residential setting and single-handedly. And so I decided to write one up based on my experience.

The article (with photos) came up to be rather long, and I decided to split it in 3 parts. This Part 1 covers the introduction, what you need for the job, and ITC removal. Part 2 covers ITC disassembly and cleanup. Finally, Part 3 covers assembly and installation.

By the way, the notorious ITC is used by Mercedes on several vehicle models, so this write-up is applicable (with some minor adjustments) to the GL-Class (X164), M-Class (W164), and R-Class (W251) from as early as 2003 through 2012. Do not take this article as an authoritative procedure. There may be better ways to do this and that. It will be good to read additional tips and feedback. All of this will help the D-I-Y community. The usual disclaimers to follow: wear eye protection, ensure the vehicle is safely anchored on jack stands or ramps, beware toxic or flammable chemicals, do not run engine inside a garage without ventilation, etc.

Here we go now. This is the list of what you may need to complete the job:

1. Generic tools
   • Lift, pit, ramps, and/or jack stands
   • Jack or hoist
   • T55 bit
   • 16mm socket
   • E12 socket
   • HW8 bit
   • E10 socket
   • U-joint
   • Wobble socket extensions
   • Powerful impact wrench
   • Torque wrench
   • Large flat screwdrivers
   • Needle pliers
   • Hammer
   • Deadblow or rubber mallet
   • Work lights
   • Steel brush (optional)
   • Pan/bucket/box for parts
   • Air compressor + nozzle
   • Wood blocks
2. Special tools
   • Universal E12 socket (optional)
   • Seal drivers (optional)
   • Bearing drivers (optional)
   • Large snap ring pliers (3" spread)
   • Ring compressor
   • Large syringe (optional)
3. Consumables
   • Lots of paper towels
   • Gloves
   • Goggles
   • Corrugated carton (large box)
   • Rust penetrant oil
   • Brake parts cleaner
   • Assembly grease
   • Acetone
   • RTV silicone
   • Loctite threadlocker
4. Common replacement parts (based on your needs)
   • Transfer case drain plug (need 2), p/n A0029900612 $3.53
   • Transfer case washer (need 2), p/n 007603016105 $2.03
   • Transfer case input seal, p/n 0169973646 $27.75
   • Transfer case rear output seal, p/n 0159975945 or 1642840045 $20.25
   • Transfer case front output seal, p/n 0159975845 $16.50
   • Transfer case w/o shift motor, p/n A2512802100 $1,800
   • Transfer case chain, p/n HV-091 $89.50
   • Transfer case chain guide, $43
   • ATF Fluid 134 1QT 236.14 (need 0.5) $11

ITC Removal

The ITC removal is the first step in the process. Raise the vehicle on jack stands or ramps. You may want to allow exhaust to cool down as both pipes are very close to the ITC. No need to drop exhaust or drive shafts unless you want additional space.

1. Use jack or hoist to support the transmission. You will remove the rear bracket, and will need support. I used a 2x6 block of wood and floor jack under the pan.
2. Examine and apply rust penetrant oil on the shaft coupling. In my case the front shaft flange and coupling rusted and needed minor spraying. You will see the rusted joints easily. Spray into the seam (rearward) and avoid contaminating other parts or exhaust pipe. Spray a little, use hand to rotate the shaft, spray a little again. Use paper towel as a shield. The penetrant will do its job while you work elsewhere.
3. Remove the driver's side aux bracket arm.
4. Remove the passenger's side aux bracket arm.
5. Unbolt the transmission bushing 2x 16mm bolts.
6. Remove 6x 16mm bolts holding the transmission bracket to the car. Remove the bracket.
7. Remove 6x T55 bolts from each front and rear drive shaft coupling. Use a deadblow to loosen rusted flange if necessary. Move shafts to the side and let them hang. The rear shaft can be pushed back by hand enough to clear ITC flange and move up and to the driver's side.
8. Remove 8x E12 bolts holding ITC to the transmission. The top 2 bolts can be tricky. The passenger side top bolt is fairly easy once you assemble a good extension. E12 socket + short extension + U-joint + extra-long wobble extension at 45-degree angle down + impact wrench. I used very powerful Milwaukee 2767 M18 FUEL - piece of cake. The driver's side top bolt is a PITA as many pointed out. I used GearWrench 80982 Universal E12 socket + medium wobble extension + U-joint + long extension between shaft and exhaust + impact wrench. For both top bolts I had my left hand go from the back of ITC topside to hold the socket in place while working with the other hand to assemble the extensions and then drive it. A powerful impact is a must IMHO.
9. Place some support under the ITC as it is too heavy (50 lbs) and cumbersome to hold by hands. I used a plastic step stool. Wiggle ITC backward about 1.5 inches to disengage the input shaft. ITC will abruptly drop.

alx

i applaud you for your effort. this is knowledge the regular diy guy can really appreciate.

now, i am not your mom, but please make a habit of wearing suitable steel toe shoes or work boots. trust me. your toes are crunchy, heal slowly and never really heal once hurt

johny75

Hey max, you actually sent me a PM to this post of yours, Thinks!!!, ... as I had a question on removing my front shaft. Sorry, I just now noticed the PM, .. Anyway, reading the steps above, it looks like you were able to rotate the shaft somehow. How??. If I use ramps to lift my car, I can't do it, its is not moving, even in neutral. Am I missing something, maybe you were on 4 jack stands. I am basically puzzled on how to get to the bolts on the top of the shaft without rotating the shaft. Thanks!

maxusa

You are correct. I had my truck on jack stands with wheels freely suspended and turning. I turned the shaft by hand, and observed wheels turn in opposing direction (as they were supposed to do). Hope this helps.

johny75

and your tranny was in Park , engine off, and you could still spin the shaft on jacks? thx!

maxusa

Frankly, I do not recall which position the transmission was at the time. I guess either P or N. I did a 722.9 tranny/torque converter fluid service immediately before the ITC rebuild. That procedure ends with the transmission in P. I remember it was not easy to rotate the shafts by hand, but possible with nitrile gloves. If I shifted in N, then I regrettably omitted this step from the write-up. Thanks for pointing this out.

johny75

ok, thanks. I guess I have to test that before undertaking the job. Since the snifter is electronic, if you put it in N and then shut the car off,I thought it goes to P automatically. I hope the car does not have to be running in N in order to be able to rotate the shaft. Thanks again.

maxusa

I am 100% certain my engine was NOT running. You can shift into N with ignition ON and engine OFF if needed. I am certain that you will find the correct configuration to rotate the shafts.

bobfig

Thanks for your thread. My ML320 2008 is 100K and the seals aren't leaking. Do you think it's possible to do this job, for replacing only the chain, opening the top half without removing the ITC from vehicle?

bbspoolside

JamesMitchell

Maxusa - Brother, man, your detailed write up was spot on!! Just completed my transfer case chain and seals kit rebuild. Your experiences over the three part series helped me tremendously! Thank you so much for taking the time to detail all of your procedures and pictures. I think this was a 7-8/10 type project for the typical DIY person. Now having done it, It's probably more like a 6/10. The learning curve is high but the rewards are so worth it!

A couple of thoughts:
1. Compression springs to remove gears: Your idea to fabricate a compression spring tool worked well for me. I bought the same metal box material from Home Depot you detailed and used two zip ties. It took some work but the splines came out as you described. BTW, for those who are going to do this - when reinstalling the two splines (with the compression spring), there is a diffuser lip that will automatically compress the compression spring as you reinstall. NOTE: when reinstalling the splines, as Maxusa describes in his pic, sometimes the bearing will move outward, requiring you to reseat them to make them flush with the case.

2. Reinstallation: before you apply the silicon around the case for reassembly, with the two gears and chain removed, do a dry test of the two shells to make sure they will go together. I discovered that one of my bearings on the input shaft was not recessed (as shown in Maxusa's pics), thus, the two halves would not go together. I used a 3" pvc pipe to make the bearing more recessed and then dry tested the two halves together again. Once you have dry tested the two halves to make sure they will go together, then you will be ready for the silicon gasket and ready to put the two shells together.

Thanks again, Maxusa on your detailed writeup. Sure, I could have bought a reman. unit or a new unit, but I feel like the TC is as clean as it was when new, the seals are in place as they should be, and the TC should last for years to come. Good luck to anyone attempting this project. Feel free to PM with any questions.

maxusa

James, thanks for good points and kind remarks. This is the sort of feedback that encourages people to contribute to the DIY community. I am very pleased that my storyboard helped you.

bobfig

I have been lucky in that job!

• 10/5/2018 - Km 153.800 – ITC only cover removal - chain replacement (old one had about 35 mm deflection, new shows only 10 mm) – Surprise - one of the chain guide bases was broken and welding in place is not possible/recommended. Solution was bonding with tekbond and prolonging its thread/bolt about 1 inch (original bolt is 5x25 mm torx inox, improved bolt now is 5x50 mm alen inox). Besides, I put a kind of "shim" against the ITC sidewall for the bolt have no chances to displace in that direction. Filled in with 0.45 liter Febi 29449. I have purchased a new chain guide but the old was still good. The seals were Ok too. Today, after 10.000 km, everything is running well.

IH1

Anyone have the chain guide part number ? Thanks !

bobfig

MB Transfer Case Chain Guide (ATC400-Chain-Guide) = $42.99 at https://cobratransmission.com/BMW-MB...se-Chain-Guide