Transmission issues summary

[bcredliner]

It has been impossible for me to determine if all the transmission problems posted happen to all the transmissions or if some are more problematic than others. Further, I can't decipher what transmissions are prone to which particular problems.

One of the reasons I am interested, while I am not having any transmission problems, I am over 100,000mi on the original transmission. When I have transmission problems I would like to be able to consider any other compatible transmissions that would be more reliable and able to handle more torque than my original transmission. Thus far, my take is I would have to pay big bucks for an aftermarket improvement.

[bcredliner]

Originally Posted by bcredliner

It has been impossible for me to determine if all the transmission problems posted happen to all the transmissions or if some are more problematic than others. Further, I can't decipher what transmissions are prone to which particular problems.

One of the reasons I am interested, while I am not having any transmission problems, I am over 100,000mi on the original transmission. When I have transmission problems I would like to be able to consider any other compatible transmissions that would be more reliable and able to handle more torque than my original transmission. Thus far, my take is I would have to pay big bucks for an aftermarket improvement.

Can anyone answer the question of which transmissions are problematic, which are prone to what problems?

[srmmmm]

It appears to me the people with the most problems are those who number one: perform frequent fluid changes (possibly with the wrong fluid); number two: reprogram or modify their transmissions, and number three: misinterpret worn driveshaft splines or low vehicle voltage as a transmission problem. I think the units are quite reliable under normal driving conditions. However, due to the higher performance characteristics of the X5 itself, many of us take on a more "spirited" driving attitude, thus advancing the normal wear cycle of the driveline. I have 242,000 miles on my 3.0 with a build date of October 2002. The fluid has never been changed and I have done at least 15,000 miles of towing a 1300 pound PWC & trailer in Texas heat with no problems at all.

In past lives with GM turbo 350s, 400s, 200Rs, a fluid and filter change every 30,000 miles was the norm. But with newer synthetic fluids and the precision of electronic controls, the internal wear factors have been sharply reduced.

[bcredliner]

Originally Posted by srmmmm

It appears to me the people with the most problems are those who number one: perform frequent fluid changes (possibly with the wrong fluid); number two: reprogram or modify their transmissions, and number three: misinterpret worn driveshaft splines or low vehicle voltage as a transmission problem. I think the units are quite reliable under normal driving conditions. However, due to the higher performance characteristics of the X5 itself, many of us take on a more "spirited" driving attitude, thus advancing the normal wear cycle of the driveline. I have 242,000 miles on my 3.0 with a build date of October 2002. The fluid has never been changed and I have done at least 15,000 miles of towing a 1300 pound PWC & trailer in Texas heat with no problems at all.

In past lives with GM turbo 350s, 400s, 200Rs, a fluid and filter change every 30,000 miles was the norm. But with newer synthetic fluids and the precision of electronic controls, the internal wear factors have been sharply reduced.

I would be among those that change the fluid (every 50,000) miles. My transmission is also modified with Dinan transmission software. I also have all the Dinan mods plus nitrous. I am in Texas also, and have the original transmission at 110,000mi. That means there is at least one transmission in service that is still performing as intended having done all the above.

My question is--when a particular BMW transmission fails what are the likely causes in descending order of likelihood.

[JCL]

Originally Posted by bcredliner

Can anyone answer the question of which transmissions are problematic, which are prone to what problems?

I don't think there is any consensus on that question. All of the automatics in the X5 (GM, ZF, 5 speed, 6 speed, 4.6 variant) have had some amount of failures. Those failures don't appear to have been related to wear out due to overheating or overloading most of the time, but rather sensors, actuators, and random failures that are not precipitated by distance or load. The exceptions to that would be the 4.6 torque converters, and the early diesels (the GM trans was under-spec'd in the first diesels). It is really difficult to engineer in reliability after the product has been designed and manufactured. It involves a long development and testing process; neither is practical for an owner. You can't improve base reliability by doing things that aren't related to the common failure modes, ie replacing the fluid. That particular one usually won't hurt, but it isn't likely to help.

I don't think it is practical to swap in a different automatic. You would give up the electronic integration most likely. You could swap in a manual, but that seems like a lot of work.

Personally, I would just work to reduce the risk to the minimum possible, within the constraints presented. That is why I recommend ZF fluid and OE filters, for example. They aren't necessarily that much better, but they are lower risk.

[TiAgX5]

Originally Posted by JCL

.......That is why I recommend ZF fluid and OE filters, for example. They aren't necessarily that much better, but they are lower risk.

I would have gone with the ZF fluid had I researched the topic more throughly B4 my 100k fluid/filter swap. I was listening for trans noise post fluid swap for around a year (20k miles). Now that my trans has gone over 70k on Castrol I will be continuing with it to see if I can get to over 200k (no plan on selling the X, drilled slotted rotors/refinshed calipers/CC pads and KW C'overs are going on soon, sub-10k value on '03 4.4 is not enough $s for overall condition).

[JCL]

Originally Posted by TiAgX5

I would have gone with the ZF fluid had I researched the topic more throughly B4 my 100k fluid/filter swap. I was listening for trans noise post fluid swap for around a year (20k miles). Now that my trans has gone over 70k on Castrol I will be continuing with it to see if I can get to over 200k (no plan on selling the X, drilled slotted rotors/refinshed calipers/CC pads and KW C'overs are going on soon, sub-10k value on '03 4.4 is not enough $s for overall condition).

I think that is a very reasonable approach, to continue with the fluid that worked for you. My only caution would be that without a spec to conform to, any fluid is subject to changes from time to time and the fluid you buy one year may be different than what you buy a year later. Oil companies are pretty famous for changing their fluids in the interests of marketing, usually calling it reformulation. What the spec does is provide some comfort that there is a standardized fluid being offered.

[bcredliner]

Originally Posted by JCL

I don't think there is any consensus on that question. All of the automatics in the X5 (GM, ZF, 5 speed, 6 speed, 4.6 variant) have had some amount of failures. Those failures don't appear to have been related to wear out due to overheating or overloading most of the time, but rather sensors, actuators, and random failures that are not precipitated by distance or load. The exceptions to that would be the 4.6 torque converters, and the early diesels (the GM trans was under-spec'd in the first diesels). It is really difficult to engineer in reliability after the product has been designed and manufactured. It involves a long development and testing process; neither is practical for an owner. You can't improve base reliability by doing things that aren't related to the common failure modes, ie replacing the fluid. That particular one usually won't hurt, but it isn't likely to help.

I don't think it is practical to swap in a different automatic. You would give up the electronic integration most likely. You could swap in a manual, but that seems like a lot of work.

Personally, I would just work to reduce the risk to the minimum possible, within the constraints presented. That is why I recommend ZF fluid and OE filters, for example. They aren't necessarily that much better, but they are lower risk.

For clarification--the 4.6 torque convertor does not hold up as it should?

I think changing fluid is better, especially if a common failure works because of the lubrication or fails because of too much friction. I agree, changing the fluid may not prevent common failures but it should not hurt.

[TiAgX5]

Originally Posted by bcredliner

It has been impossible for me to determine if all the transmission problems posted happen to all the transmissions or if some are more problematic than others. Further, I can't decipher what transmissions are prone to which particular problems.

One of the reasons I am interested, while I am not having any transmission problems, I am over 100,000mi on the original transmission. When I have transmission problems I would like to be able to consider any other compatible transmissions that would be more reliable and able to handle more torque than my original transmission. Thus far, my take is I would have to pay big bucks for an aftermarket improvement.

Brian, I think we have the same trans (5HP24) except you have a slightly larger TC (due to the extra grunt of the 4.6). I did a fluid/filter change (3 drain/fill, new filter on last fill) at 100k miles. 173k miles now with no issues (even using the Castrol Multicar Import, some on here and B'forums stated failure would soon follow because of missing "friction modifiers"). Planning another series of drains/fills soon and will be checking the pan mags closely.

There's no such thing as a lubricant with infinite life (even syns) and I'm suspect of BMWs motivition in making such a claim at the EXACT time they began no charge sched maint. Even the maint sched provided with my X stated 100k fluid swaps, when I pointed it out to the Senior SA at a Florida BMW dealer it was dismissed a printing error. In the same breath he informed me that BMW translates trans lifetime as 100k miles.

[bcredliner]

Originally Posted by TiAgX5

Brian, I think we have the same trans (5HP24) except you have a slightly larger TC (due to the extra grunt of the 4.6). I did a fluid/filter change (3 drain/fill, new filter on last fill) at 100k miles. 173k miles now with no issues (even using the Castrol Multicar Import, some on here and B'forums stated failure would soon follow because of missing "friction modifiers"). Planning another series of drains/fills soon and will be checking the pan mags closely.

There's no such thing as a lubricant with infinite life (even syns) and I'm suspect of BMWs motivition in making such a claim at the EXACT time they began no charge sched maint. Even the maint sched provided with my X stated 100k fluid swaps, when I pointed it out to the Senior SA at a Florida BMW dealer it was dismissed a printing error. In the same breath he informed me that BMW translates trans lifetime as 100k miles.

BMW says the fluid lasts a 'lifetime'. I don't recall a communication from BMW saying WARNING--Do not change the transmission fluid. I change the fluid because I believe the capability of the fluid to properly lubricate declines as miles increase.