Need Some Advice
 

Hey all, long time lurker, first time poster.

So I have had my 05 4.8iS for about 2 years now. Bought it at 70k now just crossed 102k.

Love the car, however it is starting to have some issues. Particularly with the transmission. It seems to be slipping while driving especially in automatic mode in higher gears. 5th is the worst. I actually skip over it since I only drive the car in manual mode.

So my question, what happens is this situation? Any ideas for a fix? Used transmissions aren't too bad but I don't want to deal with this issue again.

Any help is appreciated since I'm also considering trading her in for a smaller vehicle if I have to.

My .02 cents

- Find an Indy shop that has BMW specific platform like GT1 or DIS or ISTA - scan / run diagnostics
* for stored codes - hint if transmission slipping, and other module(s)/
factor(s) for the root cause.
* check for electrical gremlins - battery / alternator / and more
* check fluid level

Also, try to contact propellerhead his indy did some good troubleshooting and replacement of specific parts in his vehicle trans (your vehicle might be a close clone of his).

Good luck! you might be surprise! it might be just a simple fix for all the hassle you are experiencing / described above.

Mine was a different story (3.0 with GM Trans:
http://www.xoutpost.com/bmw-sav-foru...on-d-mode.html

Here's a link to problems associated with the ZF6HP26 trans as installed in a BMW. The fact that your trans is slipping leads me to suspect the torque converter could be one of the problem. The ZF6HP26 trans was the first trans that could lockup the torque converter in all forward gears.

Common Problems Associated With The ZF 6HP26 Automatic Transmission

As quote from the website on BMW lifetime ATF.

"Service interval recommendations are too long (BMW). On BMW vehicles equipped with this transmission, the factory rates the fluid to last a lifetime. The unfortunate fact is that this is simply not accurate. Tests have shown that the fluid starts breaking down at around 62,000 miles. It is therefore recommended that the fluid be changed every 50,000 miles. Doing so will assure you a long transmission life span."

Yeah the torque converters do fail on the 6hp but some diagnostic analysis needs to be performed to determine where the customer should go. If the Tranny never got any fluid and filter service then I would suspect that the tranny is on its way out component seals have begun to break down. If I had purchased at 70K I would have replaced the trans fluid along with the mechatronic for piece of mind service.

I would think if he wants to keep the truck he would install a remanufactured trans, or find a shop that specialize in tranny rebuild. Most remanufactured trans offers a better warranty than a trans that is rebuilt.

Wow thanks for the responses guys.

As far as a replacement trans, they are expensive. As much as an LS engine.

If that puts things into perspective haha.

If someone would be so kind to provide me with some estimates of costs so I can figure out if it is worth it for me I would greatly appreciate it.

If it were mine, I would have an Indy do a transmission service, (look in Yelp and read the reviews) particularly if it had not been done at all or for many miles. Involves removing the trans pan, 4-5 quarts/litres of trans fluid, uses zf lifeguard 6, expensive stuff, changing the filter, cleaning the pan which has magnets that catch the fine metallic particles. These particles end at the bottom of the pan and can cause the solenoids to foul up as they are close to the bottom of the transmission. The solenoids activate the shift points. Doing the service is a good place to start. I am thinking it will be $400+ but perhaps solve your issues. This 6HP26 ZF transmission must use the ZF fluid mentioned. on the passenger side of the transmission is the mechatronic sleeve, an electronic connection to the trans...this often weeps or leaks fluid, which might also be your problem, low fluid, so doing the service is wise.

Thank you for the advice. I will try this first and foremost.

I agree with the above. In fact, I need to get mine done soon... nearing 100k miles myself. If I remember right, on my last X5 I paid ~$450 for a good indy to do it.

I agree that it does sound like the torque convertor and also to take it to a recommended transmission shop for diagnosis. More often than not once there are symptoms such as you are experiencing a fluid change will not fix the problem. Since it might not fix the problem, that is the reason to have it checked out by a qualified tech first.

If its the torque converter it will eventually trigger the check engine light. At that point a hard enough code should be generated to further substantiate the analysis. On some of the torque converter cases the unit starts to deteriorate so much that it begins to whine. When this happens bits and pieces have come off the converter and are travelling through your transmission. You want to avoid the situation getting to this level because at that point the transmission will need to be replaced(remanufactured best). If you catch the torque converter failure in the early stages then you just replace this component and the trans is still good.