From 4WD to 2WD. Leaking Transfer Case - Do I still need it? CX-9 2010

If you have a minute I want to get your quick thought on something that might sound crazy. I am the 2nd owner of a 70K miles Mazda CX-9 GT from 2010.

My transfer case (TC) was leaking and upon verification the dealer said the output shaft failed and I lost 4WD. After trying to sell me a new car or a new transmission, the dealer said that I should have no issues driving the CX-9 as 2WD automobile and put back the TC. The dealer did not care to reseal the TC and I have a leak again. Going back to them they did not bother looking at the TC and they say I need a new car, or a new transmission and transfer case.

Here is the question: Once I permanently turn off 4WD, can I just drain the TC so I dont worry about risk of fire (the TC is by the exhaust and its known for potentially causing fires)? I assume that if the TC is not just for 4WD than this wont work.

Any thoughts on this?
 
if you drain the TC (which you can't because there is no drain plug) the gears will still turn and they will get hot and eventually the TC will explode because it will seize. Your best way is to completly remove the TC, yes car will still run, i have done it as plenty other people, do a search here. You just take it out and put back the passenger side axle and remove the main drive shaft completly.
 
if you drain the TC (which you can't because there is no drain plug)

There's no drain plug, but there is a fill plug. PITA to get to, but it's doable. Then you use a vacuum to evacuate the goo. This only works if your fluid isn't completely cooked, which I suspect it is.

One option -- depending on how much you're willing to spend -- is to find a good transmission shop and get a quote to rebuild your tranny and install a new PTU. My 2011 AWD had 90k when it started feeling odd as I drove. Took it to a local, reputable shop. Confirmed the PTU was toast and it took out the tranny with it. The splines were ground down.

And the AW21 transmission has issues with the bores in the valve body experiencing a high degree of wear. Don't know if that's related to PTU failures, but it's worth seeing a transmission shop to drop the pan, swap the fluid, and at least inspect the valve bodies. My transmission guy said he's not seen one valve body without valves that are worn out. Usually he's had to replace the whole thing. He has a bunch of dead PTUs and valve bodies around for show and tell. Also the B1 servo pins fracturing, causing slips.

Maybe split the difference and get your transmission rebuilt and nuke the PTU. It was 2800.00 to rebuild my transmission and my cost-benefit analysis led me to make that choice. I'm keeping mine for at least a couple of years. 2800.00 is less than a down payment, my car is a known quantity, since I know exactly what maintenance I've done, no car payment.
 
if you live in a warm climate and never do any off roading than taking it out is probably your best solution. Easy, you need to remove the cat converter which is the hardest part but honestly it is not all that bad, you will probably need new exhaust gaskets but that's it. Any independant shop can do this, don't need to pay the big $ at the dealership.
 
Thank you both @DudeInPHL and @puma !
I live in the Pacific North West. Except this summer its rarely hot, we get a lot of rain and occasionally drive to go skiing for a couple of days.

Same here, I dont have any payments on the car and it just turned 70K miles and I think I am better off keeping the car even if the car market was less crazy.

I will call some shops and see what feedback I get.

@puma how many hours of labor would you roughly estimate for such an operation?
 
@puma I spoke today (via the phone) with a transmission shop and they dont understand how this can be feasible. I am not sure I understood perfectly their concern but it was something on the lines of the car not being able to function because after removing the TC the passenger axel shaft wont allow the car to run.. Not sure if this makes sense. Do you have any thoughts? Thanks so much... !
 
Yes, you can't see it but the passenger side axle shaft actually goes across the TC and hooks inside the trasmission so once they remove it, they will see it is doable. I understand their concern as I had the same but it does work.
 
I haven't had any problems with mine, you might have the rusted exhaust bolt which are a pain but other than that it is pretty straight forward.
 
I'm considering doing the transfer case delete on my 2009 cx9. I would like to keep the vehicle long term so one question I have is once the transfer case is gone will there be any parts of the transmission that could be damaged over time due to dirt or rain since they are now exposed to the elements?
 
Thanks for the reply. So the hole where the transfer case splines insert into to the transmission is sealed on the inside? Am I understanding that correctly?
Also do you think removing the transfer case and driveshaft will cause the rear differential to cause any banging because it isn't fully supported?
Any other concerns or advice? I've been researching this for a while and you're the only person I've found that has successfully completed this and is willing to share, so I really appreciate the help.
 
here is what it looks like without the transfer case. You can see the transfer case doesn't seal anything with the transmission. Rear diff will support itself but you need to remove the driving shaft from the car obviously. It really is a no brainer modification, you'll see it when you take it out, really not complicated.

thumbnail_IMG_1208.jpg
 
OK, last question... probably. Haha.
Once the transfer case and axle are removed will any parts inside the rear diff ever be moving? Say if it had a leak and ran out of fluid. Would it matter? The axles to the rear wheels are still connected to it obviously, so I've always been confused on how that part functions, especially with the AWD on-demand setup.
 
yes the wheels will still make the diff turn. it will be exactly like when the car drives in 2wd and doesn't need the extra traction from the rear and is not coupled with the main driveshaft
 
Hi @puma , Good day!

I stumbled across this thread as I am having the exact same issue right now with my '08 GT. I hear an airplane sound underneath my car when I'm doing 20mph/30kmh, exactly like what is described in this YouTube video. Initially I thought it was the wheel bearings and other suspension parts, but when I had all of those replaced, the noise is still there.

So when I had it checked by another mechanic, they determined that it actually is the PTU that's causing the noise. So I did a transmission and TC pulldown, and when they opened the TC, they saw that there's no oil on it anymore, it seems it got dry it's now a sludge, and the gears are not in good condition anymore. They recommended to have the entire TC replaced.

I live in Southeast Asia, and it's really, really, really hard to get a replacement part for this locally (unless I have it air shipped to my country from US, which is not an option for me right now). Because of that, my car is stuck in service center for almost a month already, so I am now considering doing transfer case delete/converting to 2WD. This is also the same recommendation I got from my mechanic, and he assured me that the car will still work even without it, and I read on this thread that this can really be done as you mentioned.

So I have several questions before I do this:
1. Can this be a permanent fix or this is just temporary and I still need to get a replacement PTU as soon as I am able to? I want to keep the car long term and I don't really do off-roading so I don't really mind losing the 4WD.
2. Do I need to reprogram anything on the car's computer, say turn off the 4WD completely so that it will be just 2WD? And do I also need to remove the rear driveshaft?
3. My mechanic is saying that he still needs to reattach the busted TC except the propeller part so that it won't utilize the 4WD, is that really necessary or the busted TC can be totally removed from the car without causing any issue (aside from the rusted exhaust bolts you mentioned on this thread).

Thank you so much!
 
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1 it can be permanent
2 no need to reprogram, center drive shaft needs to come off, side axles no.
3 TC can be removed completly
 
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