I wanted to follow up on this thread. I began to have the transfer case chain problem about a year and a half ago. I bought the chain, chain guide, seal kit, tranfer case fluid and sealer intending to replace the chain soon. Well, that was Nov 2017. I finally took the TC out a couple days ago and here are the pics of the inside. The chain guide mounts broke off and the chain guide was sitting in an area at the bottom of the TC. Also, the magnet had come out and is smaller. I realize I should have replaced it sooner - much sooner, but the truth is I drove the vehicle and had not heard the skipping of the TC chain since Nov 2017. But I had a few days off and decided to tackle it this week. So my dilemma now is what to do.. I cannot drill holes into the broken mounts for the TC chain guide (the new one is plastic now). My real question is this - If I've driven over 11K miles and almost a year and a half with a likely broken chain guide due to the loose chain, what's to say that if I just replace the chain, seals and put it back together (without the chain guide at all) will it still operate correctly? I've driven the car over 170K miles with the TC working properly. Now, over the past 11K miles, I've driven it with a likely broken chain guide. That part of the case cannot be repaired. One of our forum members drilled through the case. Honestly, with how much vibration that the TC gets, I don't want any possibility of a leak. So, do I just put it back together without a chain guide or spend $400 to get a used half that I can bolt a new chain guide to. Or just get a new unit for $1,800. Yes, I know the prudent thing to do is just get a new unit and not worry.

I talked with John at Cobra Transmission and asked what he thought. He said, that without the chain guide the chain will eventually slap against the bottom of the transfer case and eventually cause a leak and or "explosion." Looking further into the matter of other Integrated Transfer Cases, most transfer cases do not have chain guides - they just have two sprokets and a chain. There are some Integrated Transfer Cases that share the similar case (like BMWs) that also use a chain guide. But after driving this car for 11K miles without a problem or leak - just knowing that my TC chain was loose and broke the chain guide along the way, I'm inclined to properly put the seals in, new chain and forego the the chain guide altogether. If in the future I hear the slipping of the chain again, I will then change out the the entire transfer case and buy a new one. A new one at Cobra is $1,800. I'm not trying to be cheap about this, but I really don't want to spend $1,800 or even entertain a used one, as John from Cobra said about 1/2 of the TCs that they receive as cores have the chain guide studs broken like mine was. The chain guide was obviously a design flaw. Noteworthy - there are no marks on the inside of the case at all where the chain may have "slapped" the case. I'm sure the chain got loose enough to break the chain guide, but it didn't get loose enough to "slap" the inside of the case. I'm thinking about putting it together without it. If I got 170K miles before a TC issue, whose to say it won't last another 170K with a new chain and no chain guide.

Would love to hear anyone's thoughts on my proposal. Below are the pics:

 

Hello James, the residue is remarkable and is possibly an indication of ITC general wear. I would check the bearings and sprockets for wear. I see that the chain rubbed off portions of the chain guide posts. So a restoration will be complicated. I share your resentment to spend large dollars in general, and in your case in particular. I would recommend to assess your plans about the vehicle. If you plan to use it for many more years/miles, then, perhaps, you can justify somewhat higher investment in repairs. Sadly, vehicles deteriorate and wear out and require increasing expense to maintain in top condition. A quick cursory visit to eBay yields used ITC between $450 and $800, many open to offers. Items 163605763487, 254152226541, 183761718621, 264198687768. This is possibly your best bet. I would not simply remove the chain guide and risk catastrophic drivetrain failure at highway speeds. My 2 cents. Hope this helps.

 

Maxusa, thank you for your thoughts. I'm leaning towards either a new transfer case for $1,800 or put it back together without the chain guide. I really believe getting a used TC or just the half with good chain guide studs is a recipe for future failure - based on John (from Cobra) saying 1/2 of the cores he gets have broken chain guide studs. You're right, upon further inspection, my current chain guide studs do have wear from the chain. You can see where the chain ate at the studs. But look at the distance from the wear at the chain guide studs to the outside (inside portion) of case. In my case, even with a very loose chain its evident the chain did not stretch far enough to reach or slap any part of the outside portion of the inside of case. And this is with a 180K loose chain. Also, John said the bearings, and gears are very tough on this MB transfer case and rarely need to be replaced. He said he sells 1 or 2 sets of gears for every 100 TC chain he sells. However, the seals do need to be replaced or you risk getting a leak. I'm going to clean everything up and inspect it and let you know what I decide. Thanks again for all of your helpful instructions in your transfer case post!

 

You are welcome. I am glad my writeups help. About your remark on what Cobra said. Their stats can be very misleading. First, Cobra does not reveal how many ITC cores they get. We cannot begin to assess if their sample is statistically representative. It is unclear how much ITC core market share Cobra holds to make sweeping inferences. We do not know the ITC chain guide failure rate. Secondly, we do not know if these failed ITC cores had high mileage, been ever maintained, towed heavy loads, operated in extreme temperatures. Perhaps, your use pattern is different. I caution anyone against making conclusions based on anecdotal evidence. The fact is that there is vastly more reliably working ITCs out there. Having taken the ITC apart, I would not hesitate a used replacement from a lower mile donor vehicle.

 

Maxusa,
You bring up some great points. And you're absolutely right, we cannot assess what Cobra has done with regards to transfer cases as statistically representative. They are only seeing the TCs that have had problems. Mercedes has the GL, ML and R classes that all use the ITC (Integrated Transfer Case). And you're right that getting a used lower milage transfer case is a good option as a replacement vs a rebuilt or new. My assessment of used transfer cases above is flawed as Cobra is only getting transfer cases that have had problems. But the vast majority of transfer cases out there are working as designed and getting a good used one is a good option for someone in this predicament. This transfer case design in general is a workhorse and provides the 4matic transmissions in these and other vehicles excellent all wheel drive capability. I guess I was giving Cobra some credibility because they weren't trying to sell me a new case, a rebuild kit, the planetary gears or even the bearings. He got to the point of the matter and said the chain stretches and that's what causes the skipping or grinding noise in these TCs. He recommended getting the chain, chain guide and seal kit. The transfer case itself is built very strong and there are very few cases of this TC itself damaging to the point of catastrophic failure. More often than not, the seals will leak due to age and wear, and the chain will stretch causing the skipping or grinding noise. Also, the chain guide will often break off from one or both studs as a result of the stretched chain. There are some forum members who have drilled into the studs to install the chain guide - some have even drilled to the outside of the case and epoxied it. This may work as well, but I don't want to risk drilling into an already weak structure (chain guide studs) to install the chain guide that's already broken off and possibly risk the guide messing up the chain, gears or seals - or create a future fluid leak. The transfer case structure itself is a beast. That's why I'm considering just putting it together without the chain guide because the case itself is extremely strong and my bearings and planetary gears are in great shape. I'm planning on driving the car for a long time. I've had it since new, so I know everything that's gone into the car. I usually replace with OEM or better parts to keep it lasting for a long time. But I'm also willing to assess the situation and realize that the transfer case is extremely strong and the only weak links are that the chain eventually stretches and chain guide is poorly designed and can break off. Considering all of the above, I'm now planning to put it back together with new seals, new chain and leave the chain guide out. As a disclaimer, I am not recommending other folks necessarily do this, but after my research and examination of my cleaned up case, gears and bearings, this is what I'm going to do. I'll report back here in the future and let everyone know how it worked out. Thanks again!

 

Very good analysis. Cobra is a decent vendor. I used them and would not hesitate to recommend. One final comment about your specific situation. You may want to consider completely removing the chain guide posts, or what is left of them anyways. Yes, the new chain is not going to sag as much, but it would not hurt to ensure there is no chance the chain can rub/contact the posts, create metal shavings, stress the shell, and stretch more in the process. Hope this helps.

 

I am new to the program but found this site which was a big help. I also had the dreaded Transfer Case issue on my 2011 GL 350 Bluetec. I live in the Southern CA area and found a group in the Corona CA area that provided a replacement Transfer Case - fully refurbished. I stopped by his shop and he only does MB and BMW Transfer Cases.

The site is www.tcbmwx5.com and his email is tcbmwx5@hotmail.com. He provided a great refurbished Transfer Case for $1300 and will provide a credit of $300 when the core is returned.

If you need a great product at a great price, give him a try

 

Great find! It's definitely a niche market for the transfer cases on the MB and BMW. That's actually a really good price considering the work it takes to replace the chain and especially the three seals in the transfer case in addition to the labor to get the TC in and out of the vehicle. Thanks for sharing!

James

 

Hi James, I was wondering what was your decision and how you TC has performed so far.
Thank you.
Ricardo.

 

Ricardo,

I replaced the TC chain and the three seals. The new transfer case chain has about one year and 20K miles on it and is working perfectly. Car has almost 210K miles and is running strong - It's my daily driver. If you don't want to go through the hassle of the three seals, you could likely get away with just replacing the chain and then using sealant to put the case back together.

James

 

I did mine Tranfer case chain replace last month an a W164 2009 ML320 with 120K miles.
I would like to thank JamesMitchell for all the help and tips.
It is not necessary to remove the TC from the car.
Attached some pictures.

 

Ricardo,
Glad the repair went well. Thanks for sharing the pictures.

Cheers,
James

 

Hi all,

I'm preparing to take on the transfer case repair, hoping it is just the chain and/or minor fixes to the guide I'm over 220,000 miles and it recently started knocking occasionally on hard acceleration so I have been babying it. I had a few questions before I tackle it:
- Is it better to have the car on jackstands rather than ramps so the wheels can move? It was unclear to me if I might need to manually turn the drive shaft at some point for accessing things.
- How much more difficult is it to remove the entire transfer case vs, pop off the cover, replace chain and reseal? The idea of potentially working on repairs of things like the chain guide while under the car seems challenging but if getting to those rear bolts adds a ridiculous effort perhaps I try removing just the cover first and assess the situation.
- Is a high torque impact wrench useful? I saw a guy on youtube posted using a crowfoot and extension to get at that those back bolts which I think would negate any benefit of an impact wrench, but perhaps it would be useful for other bolts or maybe there is some flex joint I could use in combination with it. I've never really used an impact wrench at angles so not really sure the best way to do that or if that is practical.
- Does anyone have the torque requirements when re-assembling?

Thanks,

Max

 

You don't have to move the wheels for the drive shaft.. So I used ramps as it gave me more height I also raised the suspension to its max point. in theory, you can just remove the cover and inspect but the fact that it's making noise tells me the tensioner is probably broken off already. So you may need at the min need to weld it up. I used extensions and 1/2 watched to get most of the bolts off, some places used the impact gun. Its really not that bad of a job.. My concern is that you are going to take out and the have to wait for parts :-)

Good Luck!

 

Well after a solid 5-6 hours I got the transfer case out. The 2 big challenges for me were the top bolt on the passenger side and the rear drive shaft. The driver side top bolt came out easily with that reverse setup on youtube with the crowfoot. Passenger side I kept trying various ways, including that reverse set-up but couldn't get enough access to budge it. Somehow my milwaukee m12 ratchet had enough torque to get it out, but maybe all those other attempts helped. I ended up not needing to remove exhaust, but did have to remove the heat shield and that middle hanger for the rear drive shaft to create sufficient space . Used a Home Depot orange bucket to help hold the weight while I pulled off the transfer case. I was watching another youtube video where some guys lowered the transmission slightly to what appeared to create better access to the top bolts. Perhaps that would be something worth attempting.

I was pleasantly surprised to see my chain guide still intact despite some loud noises when accelerating especially up a hill. It appears to look different than others I have seen that seem to be more plastic. I am assuming maybe just a different version, but if it looks like the plastic wore off and I need to replace this let me know, the bolts are still intact so that would be an easy swap.

Other than cleaning up the inside and outside of the transfer case (is brake cleaner fine?), checking that there is smooth movement, replacing the chain and refilling is there anything else you'd suggest doing while I have it out?

 

I highly recommend you change all seals. Your ITC input shaft appears to be leaking (just like mine was at 45K miles). I can tell from the rear transmission mount covered in fluid. If you took the ITC apart, the new seals are no-brainer.

 

Ok is Cobra the best source for that? Is this the correct one to purchase? https://cobratransmission.com/Mercedes-ITC-Seal-Kit-TSK-ITC