Welcome to Tech Talk, where our resident BMW tech Nick Owen answers all your pressing BMW technical questions, frustrations, and issues. Have a question for Nick? Email him at techtalk@roundel.org. Let’s get into it.
A 317,000-Mile 335i GT
My 335i GT has covered many miles and it was diagnosed as needing to replace the front transfer case, since this car is equipped with xDrive.
The replacement of this part will cost me over $7000 at the local BMW dealership. At this point, although my vehicle is worth less than $2000 and I still love it, it arguably does not make sense to repair due to the high cost.
I have been driving this car for about eight years as my daily commuter for 150 miles roundtrip. I just had my dealership changed the cylinder head cover.
Can it be possible to disconnect the front driveshaft, and stop the whine safely. I am not driving this vehicle, since my wife just bought an X5 and I am using her X1 as my commuter. I know it will involve having many lights on the dashboard thus failing Arizona emissions, but my current tags are not due until May 2027.
Please share any advice.
Marco Chavez
Congratulations on 300,000+ miles! If this is the first transfer case to be replaced, then I have to say I am impressed. I cannot advise on whether disconnecting the front drive shaft is advisable to circumvent a failed transfer case. I have heard of some people doing this but I have no recollection of the details. I have also heard of some removing the xDrive system completely and just relying on the rear wheels instead. Safe to say there will be some lights on, I do not know how the drivability would be either. This is something you would need to experiment with at your own risk.
On the other hand, despite the atrocious cost of a new transfer case from the local dealership, I would look at this place as an alternative.
Seems you could get a rebuilt transfer case for a lot less than the dealership would charge.
Hope this helps.
HVAC Stank
Other than the smoke bomb suggestion, you gave Patrick Dougherty re: a stinky air conditioner, my automotive professor suggested shutting the A/C off five minutes before the end of the ride to allow moisture to escape the system before turning the car off. This gets rid of the moisture that causes the bad smell (usually a sulfur or rotten egg smell).
Dave Oldham
Raleigh, NC
I like that theory; I will be sure to remember that one. Thanks Dave!
Suspension induced rattles?
I have a question that falls into what must be one of the more difficult categories for you to diagnose—noises and rattles. I have a 2002 E46 with OEM Sport package/suspension, five-speed stick and about 107,000 miles. It has always had a solid feel and ride despite its age. No rattles or creaks, or indication of anything loose. I recently had a four-wheel alignment, along with replacement of the front lower control arm bushings. Ever since, I am hearing rattles seemingly coming from under the dash. Possibly near the glovebox. However, it is a bit hard to pinpoint the exact source. I have checked everything I can for tightness, and all is good.
I have heard it could be possible that new control arm bushings will stiffen up the suspension, to the point where such renewed stiffness could excite various parts that previously were not being rattled due to the previous softer transmission of road bumps to the cabin with the older worn bushings. Is that a possible/reasonable explanation? Have you heard similar experiences before where replacement of suspension components causes new cabin rattles? Or could there have been a bad alignment done perhaps? The car drives straight with no pulling.
Tim Strempfer
Laguna Niguel, CA
I have to say it is a solid theory considering the front control arm bushing on an E46 is usually worn out by 30k miles. Back in my day, that was a routine repair item that often cured a customer’s front-end complaint after replacement. However, I have to say I have never had one back and complain of a rattling noise. But if you want to isolate the noise, then you will need to start removing items around where you suspect the noise is and see if it goes away once you drive it. It is up to you on how to you want chase it. But despite the mileage, an E46 that is 20+ years old is bound to make some noises eventually.
X2 Emergency Call Malfunction
I have a 2019 X2 M35i that is a wonderful car, but had a recent issue with the SOS emergency call malfunction. I took it into the dealership for other maintenance and they said it was a small dead battery and they estimated the cost to replace it, somewhere in the roof, at over $710 as you must tear apart a whole bunch of the car to get to it.
I really have no intention of replacing it since I have an iPhone that would have a crash detection call and other means to call for an emergency, but it does put a large warning indicator light on the dashboard that disables other useful functions like engine temperature or miles per gallon or trip information.
Is there any way to turn off this warning either at a service shop or with some kind of code reset or just disable this SOS system completely so there is no warning?
I think BMW needs to figure out a better solution for that than hiding the battery somewhere that it is completely inaccessible, but I just want to get rid of or turn off the warning indicator on the dashboard. Any ideas?
Dan DeChant
Charlotte, NC
This is a frustrating thing for late model F-chassis BMWs. I have dealt with this repair a few times. Most of the time it is the battery failing. Sometimes water manages to get under the shark fin and contaminate the TCB that holds the battery. With that said, I do not know off the top of my head if there is a way to circumvent the warning light. Because it is tied into the Crash module, this tends to be a liability for BMW if there was a simple way to turn off the warning light.
Remind me on the operation: You start the car; light comes on and stays on? I believe if you press the BC button, it will clear it and allow you to see temp and MPG. I do not remember if the SOS light, then comes back on after 10 or 30 seconds or not until you start the car again?
The dealership repair is to lower the headliner to get access to the TCB and replace the battery. That repair can be a bit overzealous (and expensive) considering you can lower the rear section of the headliner and slip a hand in there to replace the battery. I have a feeling that a competent BMW independent shop can do this repair for less than the dealership. A friend of mine (former BMW tech, works for a BMW race team) recommended Caroline Eurowerks 3111 Sun Valley Place Indian Trail, NC. It might be worth asking them if they have a way of rectifying this issue whether it be through repair or possibly special software coding.
Yes, the light comes on as soon as you start the car and stays on until you shut it off. What is the BC button so I can try that?
I will reach out to this local shop that you suggested and get them to quote it as well so thanks for the information!
The BC button is the Body Control button that will clear warning lights that pop up on the dash. It will also cycle through some vehicle info on the dash. I believe it is on the end of the left stalk, turn signal lever. If it is not on the turn signal stalk, it should be on the steering wheel.
