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SKSAZ
Member
Date registered: Jun 2014
Location: Phoenix, AZ
Vehicle(s): 2006 G55, 2008 BMW 335ci, 2002 Jaguar XKR
Posts: 9
| Transfer Case in Neutral (Maybe)?
Looking for a little help....and probably bad news.
I am reasonably educated about the issues with the Transfer Case Control Module and Motor, and I have searched my issue extensively over the past couple of days. Ultimately, I have not found any previous issues which are quite the same as what I am experiencing (*my forum searching skills may not be what they should be -- but I have certainly tried). I am hoping the considerable collective wisdom of this community can help steer me in the right direction.
Two nights ago, while pulling into a parking lot (less than 10 mph), I got the large "bang" and immediately came to a stop. This was not something I have experienced before, but I am quite certain the issue was in the drivetrain. I cautiously was able to drive once around the parking lot - and it seemed there was no damage. Parked the truck and went about my business.
Within 10-15 Minutes, I return to the truck and it behaves as though the transfer case is stuck in neutral -- has all the signs (changing from High to Low does nothing - although the display on the panel does indicate normal changing from high to low, there is a terrible grinding noise if I attempt to put the truck into part while it is running).
The part that confuses me is that engaging my central locker somehow re-engages the powertrain. With the central locker locked, the truck drives normally (so far as I can tell -- I have a park near me that has a gravel/dirt parking lot for experimentation with my lockers). I am pretty sure the truck seems to be shifting between high and low range based on the performance with the central lock engaged. I was able to limp the truck home by using the central locker cautiously (I was less than 1 mile from my home - and was sure to coast around any corners with the truck in neutral/lockers off).
*The REALLY embarrassing part of this issue follows: I am afraid the central diff lock could have been engaged when driving into the parking-lot. I had an animal with me in the truck and it would not be the first time he bumped into something like this. Generally, he steps on the High/Low switch which is benign since it won't activate unless in neutral, or he likes to shift gears for me via the Auto-Stick feature of the transmission selector knob. If the dog did hit the diff lock switch, it will have been the first time he managed such a feat (and likely the last time he sees the front seat of my G55!). I can't say for certain this is what happened. I know the Diff Lock switch was turned-off before I even attempted to move the truck at all after the big bang. I can assure you all that I am well-aware of the importance of not engaging the Diff Locks on dry pavement in normal driving - if this was done, it was accidental (I know....right after he ate my homework). Believe me or not.....I can think of nothing else which would explain the large bang and subsequent symptoms.
My research thus far sounds like my symptoms are only partially explained by the known issues with the transfer case control module/motor. I should also note that the Transfer Case Shift Motor has been replaced on my truck as a condition of purchase last fall (6-7 months ago). When test driving the truck, I noted issues with shifting from high-low (it actually got stuck in neutral during one of my test drives - patience and switching back and forth eventually re-engaged high range, so we could return to the dealership).
So, my truck is stuck in the garage with no power to the wheels whatsoever unless the central differential lock is engaged. I am quite concerned that there may be considerable damage here and before I head for the dealership or independent shop (or transmission specialist?), I want to educate myself as much as possible about what I should expect and the best course of action for repairing the damage. I am mildly capable where auto repairs (DIY) are concerned -- my biggest issue is having the proper tools. I am very inclined to purchase my own replacement parts wherever possible - even if I then have to pay someone else to install them.
A couple additional details:
-I was on blacktop/asphalt in the parking lot
-The steering was turned maybe 25-30% when I got the loud bang
-There was no power on the driveline when the large bang occurred (was coasting)
-There are no error messages on the dash (I have not scanned the OBD Port given the absence of errors, but I suppose I could do this)
-I can see nothing obviously out of sorts when crawling around under the truck (very limited knowledge here)
-I am in the South Chandler/Ocotillo neighborhood of Phoenix, and although I have no love for the dealership, my experience in owning the G55 to this point suggest it is very important to find service by people who actually have experience with the G-Class. Sometimes easier said than done.
So, there we are. I am sick at the thought of needing a new transfer case because I allowed the dog to go for a quick ride to the store. While I am feeling like a fool, I figured I would come here to see how bad other members might suspect my situation is? I will ultimately see to it that the truck is fixed properly as I have intentions of keeping my G55 for a long time. I just wanted to get some thoughts about what my issue actually is before I stroll into the dealership and green-light them to "fix it" (which could be nearly as stupid as taking the dog for a ride). I am hoping someone here might have experienced something similar and be able to provide guidance.
Before this gets too elaborate, I will finish by thanking anyone who might reply for their insight. I have learned a great deal from this community, and very much prefer to read & learn vs. actively posting. I am hopeful that I might be able to get my truck back in commission relatively soon. Fortunately, it is not a daily driver, so I have at least some time to do things the smartest way possible.
What do any of you think? Other than flogging myself for stupidity - what should I do next?
Thanks,
SKS |
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: Transfer Case in Neutral (Maybe)?
SKSAZ - 3/9/2015 3:53 AM
Looking for a little help....and probably bad news.
What do any of you think? Other than flogging myself for stupidity - what should I do next?
Thanks,
SKS
I think you probably flogged yourself enough with this post, but I would certainly install a pet barrier behind the rear seat or keep the dog in a crate the next time.
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djdinaz
Extreme Veteran
Date registered: Jun 2007
Location: Arizona
Vehicle(s): 03 G55
Posts: 439
| RE: Transfer Case in Neutral (Maybe)?
Here's the power flow through the transfer case.
The blue circle is the high/low range. When low is engaged, the gear at the arrow moves down and engages the smaller cog on the shaft. When in high, the power flow follows the red line. A neutral situation exists when the gear set slid by the transfer case motor isn't engaged on either end (that sliding set at the start of the blue arrow is between high and low and spinning with the shaft).
The green circle is the center diff lock, engaged it moves the gear up and takes the differential (yellow circle) out of the power flow.
If how you describe it is such that the truck wont move unless the center diff is locked, then it sounds like something is amiss inside the center differential (essentially prohibiting power transfer). That or the control module and/or transfer case hi/lo shifter is reading incorrectly, and it really is in neutral, and engaging the center diff causes it to cycle and engage.
The point I'm trying to make (poorly) is that the transfer case high/low is independent of the center locking state. No power will reach the drive shafts when the transfer case is in neutral regardless of whether the center diff is locked or unlocked.
See this thread: http://www.pointedthree.com/disc/forums/showthread.php?tid=15093&st... You may be able to pull the wiring harness from the t-case motor, manually engage high and make a rudimentary determination if whether the shifter is at fault, or the center diff is acting up.
Edited by djdinaz 3/9/2015 10:49 AM
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Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| RE: Transfer Case in Neutral (Maybe)?
I think you have broken a bevel gear (spider gear) in the center differential, or broken the shaft that they run on, or perhaps cracked the differential carrier (thus preventing the spider gears from working). That would be the loud bang you heard. With broken spider gears, power will not be transmitted to either drive shaft unless the different lock in active (since it locks the two shafts together, the bypassing the spider gears). The TC shift motor will still continue to move the shifter fork through all of the positions (H, L, N) and will continue to report to the TC controller that the TC is in the selected gear because it actually is in gear. In that regard, everything will appear normal.
Activating the diff lock and driving on pavement would probably not damage the spider gears because they are effectively bypassed by the locking mechanism, however, it is possible the the differential carrier may have cracked due to the very high differential torques that can be caused by drive train "wind up" since there no ability to "slip" with varying wheel speeds (as happens on soft surfaces). However, the spider gears could suffer damage upon disengagement of the diff lock after driving on pavement. This might occur because drive train "wind up" stores a huge amount of energy which can be suddenly released when the diff lock is disengaged. Then, "bang", and guess which parts have to absorb that energy - the spider gears.
I can tell you from very recent personal experience that replacing a TC is not all that hard, but I ask my brother, who is also a car guy and lives in Tempe, about a good Indy for a G-wagen.
Good luck,
- FD
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chris505
Date registered: May 2007
Location: San Francisco
Vehicle(s): '79 280E/'80 280GE/'00 G500
| RE: Transfer Case in Neutral (Maybe)?
SKS,
I suspect you may have an issue inside your front axle, broken ring gear seems to be a common issue on AMG Gs that were used in 'anger'.
With the vehicle on the ground and turned off (with parking brake applied), I would put transmission in neutral (make sure center diff is unlocked), climb under the truck and try to spin/twist the front driveshaft with your hand. If the front driveshaft can rotate freely, there must be a broken CV joint or ring gear in the front axle, if the front driveshaft does not rotate freely, try spinning/twisting the rear driveshaft by hand. |
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SKSAZ
Member
Date registered: Jun 2014
Location: Phoenix, AZ
Vehicle(s): 2006 G55, 2008 BMW 335ci, 2002 Jaguar XKR
Posts: 9
| Re: Transfer Case in Neutral (Maybe)?
Guys -- Great Stuff, and thanks again. The information above is very helpful.
At this point, I am leaning towards DJD/Flooby's assessment that there must be a problem in the open diff. I am pretty convinced there is no issue with my High/Low Motor or Control Module based on the above diagram and my own troubleshooting to this point.
I am holding out hope that Chris could be on to something and will check this when I get home tonight. If there was an issue in the front-end, is is correct to say this would cause the lack of power to any wheels given the open diffs design sending all the torque to the path of least resistance?
Since my initial post, I have also noted the steering isn't quite right -- seems to be some limit in travel left to right. Still, I dare not experiment too much with this for fear of putting additional strain on whatever is still working in the driveline.
*I realize am speaking in generic/lay terms and likely demonstrating my limited knowledge, but I have to suspect a front axle issue would be less catastrophic (to my wallet) than having destroyed the center diff?
For Dutch -- yes, and the shame of it is the dog has a nice kennel for road trips. He just loves to ride along (he actually got to go by sneaking out of the house and climbing into the truck when I wasn't looking -- he isn't a stupid animal), and I figured a 5-10 minute run to the store less than a mile away was harmless - live and learn.
I will try to report back as I learn more. Since it does not appear this is a common issue, perhaps this thread will help someone in the future. |
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Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| RE: Transfer Case in Neutral (Maybe)?
Any "open circuit" in a system with three open differentials will result in the loss of drive as all shaft rotation will be sent to the path of least resistance. I should have thought more broadly and included all three diffs, plus the axles and CV joints, but I have had transfer case on the brain as of late. The asymmetric steering kind of points to a blown CV joint and/or axle stub, which would also produce the behavior you are observing. As far as "badness" goes, it has been my experience that the axle/CV joint would be the best of a bad thing, followed by the transfer case, with front differential problems potentially presenting the most challenge/cost. Used front axles are made of unobtainium, the R&R is expensive, and getting a good re-build is both tough and expensive. At least the TC and the axles are straight forward, but others may have a more informed opinion on this. |
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SKSAZ
Member
Date registered: Jun 2014
Location: Phoenix, AZ
Vehicle(s): 2006 G55, 2008 BMW 335ci, 2002 Jaguar XKR
Posts: 9
| Re: Transfer Case in Neutral (Maybe)?
OK -- having done as Chris directed, I can report that the front drive shaft spins easily by hand (truck in on the ground in neutral with the parking break on). With the assistance of my wife, I have confirmed that the front drive shaft is also spinning under power (in drive and reverse respectively).
With any luck, it appears my transfer case and high-low shift mechanism are intact. My apologies for framing the issue in a way which could have been misleading. The progress made to this point speaks volumes of the value of this board. In any case, my understanding of the workings of the transfer case has been augmented considerably.
An additional observation tonight is that the steering is in fact quite limited. I estimate maybe 15 degrees to each side (maybe 30% of estimated normal travel). I have again inspected the underside of the truck (with my focus on the front drivetrain) and identified nothing obviously wrong.
Given Flooby's response above, I am uncertain if I should be pleased or not. I don't generally get lucky in these matters.
Is there anything I can do to further narrow-down what I am looking at, or have we come to the point where we need to enlist professional help? I am aware of at least two solid independent Merc Mechanics in Phoenix, but they both a good distance from my home - obviously we are looking at towing/trailering to the shop. Alternatively, is this something a transmission shop would be suited for?
I do appreciate greatly all of you who have taken the time to speculate and provide tremendously valuable information.
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SKSAZ
Member
Date registered: Jun 2014
Location: Phoenix, AZ
Vehicle(s): 2006 G55, 2008 BMW 335ci, 2002 Jaguar XKR
Posts: 9
| Re: Transfer Case in Neutral (Maybe)?
*perhaps a silly, but possibly logical question:
In its current state, is it fair to say the truck could be driven with the central diff lock engaged? Since there is clearly an issue with the front axle/differential/CV joint, and there is no power being delivered to the front wheels, it would seem that engaging the center diff lock would be tantamount to having a rear-wheel drive G55? In such a scenario, there would be no issue with winding-up components of the driveline because the front wheels are currently free rolling.
**Please Note - I am not about to set about town in my wounded truck. I recognize that something else could fail/break at any time causing further damage and possibly creating a very real danger. My question is primarily theoretical and a mental exercise as I go about understanding how the mechanicals of the drivetrain function in my truck. |
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Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| RE: Transfer Case in Neutral (Maybe)?
I'm never lucky when it comes to these things. In fact, the fundamental operating operating principal of my life is, "probability is inversely proportional to desirability (and cost)".
Definitely flatbed it to your mechanic because if whatever is broken damages the axle tubes or diff housing, your potential good fortune could turn into a wallet busting streak of bad luck. |
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djdinaz
Extreme Veteran
Date registered: Jun 2007
Location: Arizona
Vehicle(s): 03 G55
Posts: 439
| Re: Transfer Case in Neutral (Maybe)?
Is there anything I can do to further narrow-down what I am looking at
Yes.. get the truck off the ground and engage all 3 diff locks. While the front is engaged, determine if both wheels spin freely, or if it's limited to one corner. Both wheels spinning (w/o the driveshaft turning) would indicate ring/spider gear failure in the carrier (or BOTH CVs are broke), one wheel spinning (w/o the driveshaft turning) would indicate CV/axle failure on that corner.
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chris505
Date registered: May 2007
Location: San Francisco
Vehicle(s): '79 280E/'80 280GE/'00 G500
| RE: Transfer Case in Neutral (Maybe)?
AMG Gwagens tend to be driven hard, used (briefly owned) Gs also tend to not recieve proper maintenance.
One harmful scenario is pulling out of a driveway (right turn) using full throttle and spinning one front tire (open diff-right front tire burnout) and then suddenly that wide tire finds traction and the front ring gear or pinion acts as a fuse and broken high tensile steel teeth are 'digested' by the differential components and both diff carrier bearings, both pinion bearings, and possibly the diff itself may need replacement in addition to the ring and pinion gears. The dealer will sell you a new axle rather than repair the diff, which requires many special tools and expertise to do right.
Another harmful scenario is driving a G with a loose front wheel bearing, I have only seen CV joints get damaged/broken from driving in a misaligned condition, when a loose bearing is ignored for long enough, front axle components like CV joint, hub, cv housing and axle tube start grinding against each other and usually turn themselves into scrap metal depending on the duration of the misalignment.
Check for front wheel bearing play and definately stop driving if you find any. |
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SKSAZ
Member
Date registered: Jun 2014
Location: Phoenix, AZ
Vehicle(s): 2006 G55, 2008 BMW 335ci, 2002 Jaguar XKR
Posts: 9
| RE: Transfer Case in Neutral (Maybe)?
Just a Follow-Up for all those who took time to venture a guess regarding my issue:
Turns-Out the Left Front CV Joint (or part of it) failed/broke. I just got the truck back from my Independent Shop, and the repair was not as bad as feared. I was without my truck for over 5 weeks - mostly due to the mechanic's schedule, but I was quite pleased with the final costs....compared to what I initially feared.
*I am a little confused on the nomenclature provided my the mechanic I had do the work. The replacement "Half-Shaft" had to be ordered from Germany for right around $1500. I am not sure if this part of the CV Joint or another piece of the front axel workings?
*Now that I know what broke, I am even less sure what happened? There is no way the front diff could have been inadvertently locked while I was driving on pavement (as originally speculated) -- this would take 3 separate buttons in order, and is not something that could have been accidentally achieved (I don't think). Did this part just let go given the age (and possible past abuse) of the truck? I have a 2006 G55 with right around 98,000 Miles. The truck is relatively new to me, so obviously I don't know the complete history.
Anyway -- allow me again to express my appreciation for those who took the time to respond previously. I was able to use that information to complete my own diagnosis on the truck -- and had things pretty well identified before I sought the independent mechanic. Being armed with the knowledge ahead of time prevented anyone from selling me on repairs I could established weren't warranted/required. 5+ weeks seems a little long to complete the work (and I may well not return to this mechanic because of it), but it was better than the dealer rate!
Thanks again |
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: Transfer Case in Neutral (Maybe)?
SKSAZ - 5/11/2015 5:42 AM
*I am a little confused on the nomenclature provided my the mechanic I had do the work. The replacement "Half-Shaft" had to be ordered from Germany for right around $1500. I am not sure if this part of the CV Joint or another piece of the front axel workings?
MB only sells the CV joint and the half axle as a unit, and the half axle is usually A-OK. The exact same CV joint from the original equipment manufacturer can be had separately for a lot less money. See here:
http://www.eurotruck-importers.com/index.php?main_page=product_info... |
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