Transmission Reliability

[X5Sport]

Had my E53 back for about three weeks now following a transmission rebuild. It's fitted with the same 6spd auto that the V8 4.8 has. The failure occurred at 41,890 miles and was nothing to do with the fluid - changing it would have made no difference.

The failure was within the torque converter and not the actual transmission but the broken plastic (yes plastic!) parts from the TC were ingested by the tranny oil pump destroying both it and the downstream clutches when the pressure failed. There were no warnings at all. There is no doubt that this was a premature failure and just 'one of those things' that can happen. Not that BMW GB showed any inclination to 'goodwill' the repair though!

However, this failure is not unusual and occurs on other vehicles that use the same box (Jaguar & Range Rover I'm told), though it is rare at low mileage like mine. Auto transmissions generally have a higher failure rate because they are by their nature a more complex beast. They are also much more expensive to fix - albeit with a rebuild costing approx 1/3 of a remfctrd and BMW fitted unit. Whether the transmissions fitted to the X5 are any better or worse than those used by other manufacturers depends upon the actual number of failures, and failure modes. Percentage wise it's probably around average. Perhaps an FOI request to BMW NA may reveal the true nature of the number of failures - but that might only identify those BMW know about. It won't pick up those fixed by other specialists - as mine was.

Given the option again, I would have had the 6spd manual but they are very difficult to sell on (and go for a lower price) as no one wants a vehicle like an X5 with a manual gearbox.

[HPIA4v2]

Originally Posted by X5Sport

Had my E53 back for about three weeks now following a transmission rebuild. It's fitted with the same 6spd auto that the V8 4.8 has. The failure occurred at 41,890 miles and was nothing to do with the fluid - changing it would have made no difference.

The failure was within the torque converter and not the actual transmission but the broken plastic (yes plastic!) parts from the TC were ingested by the tranny oil pump destroying both it and the downstream clutches when the pressure failed. There were no warnings at all. There is no doubt that this was a premature failure and just 'one of those things' that can happen. Not that BMW GB showed any inclination to 'goodwill' the repair though!

However, this failure is not unusual and occurs on other vehicles that use the same box (Jaguar & Range Rover I'm told), though it is rare at low mileage like mine. Auto transmissions generally have a higher failure rate because they are by their nature a more complex beast. They are also much more expensive to fix - albeit with a rebuild costing approx 1/3 of a remfctrd and BMW fitted unit. Whether the transmissions fitted to the X5 are any better or worse than those used by other manufacturers depends upon the actual number of failures, and failure modes. Percentage wise it's probably around average. Perhaps an FOI request to BMW NA may reveal the true nature of the number of failures - but that might only identify those BMW know about. It won't pick up those fixed by other specialists - as mine was.

Given the option again, I would have had the 6spd manual but they are very difficult to sell on (and go for a lower price) as no one wants a vehicle like an X5 with a manual gearbox.

Wonder if diesel with high torque cause the trans failure on yours. But again we've heard so many trans failure on petrol engine as well.

"lifetime" is made up word by lawyer since it's vague in terms of quantitative (no mileage can be put on it) and different people have different expectation in longevity. The old timer of Benz owner will balk for anything to fail under 200K miles, but new owner of benz lease theirs for 3 years.

[m5james]

Originally Posted by HPIA4v2

Wonder if diesel with high torque cause the trans failure on yours. But again we've heard so many trans failure on petrol engine as well.

"lifetime" is made up word by lawyer since it's vague in terms of quantitative (no mileage can be put on it) and different people have different expectation in longevity. The old timer of Benz owner will balk for anything to fail under 200K miles, but new owner of benz lease theirs for 3 years.

That is quite a low mileage and out of the norm. I agree w/ your lawyer statement as well.

[m5james]

Originally Posted by X5Sport

Had my E53 back for about three weeks now following a transmission rebuild. It's fitted with the same 6spd auto that the V8 4.8 has. The failure occurred at 41,890 miles and was nothing to do with the fluid - changing it would have made no difference.

The failure was within the torque converter and not the actual transmission but the broken plastic (yes plastic!) parts from the TC were ingested by the tranny oil pump destroying both it and the downstream clutches when the pressure failed. There were no warnings at all.

I've suggested this before, but never really researched it. The TC from a 740i sport has a higher stall speed than a normal 740iL. While I've heard of shifting problems in the E38 forums (my assumption is mostly due to lack of fluid changes), it's not as bad or complete failures like I read about here. I've always wondered if we could swap in the 740i Sport TC, hoping that maybe it's a little more stout since the stall speed is different, plus it'd might be a nice little upgrade.