Diagnosing my X5 issues

[RToth]

So, I will use this thread to keep track of and help me diagnose the actual problem with my newly acquired X5, time will tell if it is an electrical issue or actual mechanical failure of the trans itself. http://www.xoutpost.com/bmw-sav-foru...-cheap-x5.html is the problem child.

Previous owner said on a couple hour drive to his fathers house to visit the trans began to act up and stick in 5th gear, he finished the drive without issue other then low power due to being in high gear. It has been parked for the last couple weeks before I bought it the other day. When I got there to check it out I drove it around their yard, no clunks at all when shifting to drive or reverse, but when I went to accelerate I could feel the ABS kicking on. ABS would stay on but as soon as I would let off the gas pedal and try to go again the ABS would shut off and all was normal. This is also coupled with ABS engaging at low speeds when on the brakes. No lights on the cluster for ABS or DSC ever came on.

After driving it around the yard a bit I gave the guy the money and made the drive home, maybe two miles. For the most part the drive was fine, I ended up getting a flashing check engine light (on the domestic cars I'm used to this is usually a catalyst damaging issue / multiple misfire) and the engine began to misfire but still got to speed with ease and shifted through all gears flawlessly. At 60 MPH I floored it and when it went to downshift it instead just free revved at which point I let off and just kept 60 MPH still without any issues.

Got it home and backed it into the driveway, misfiring pretty good, I grabbed my scanner (Scangauge II) and found P0720 and P0000. I cleared the codes and immediately the engine stopped misfiring and ran perfectly smooth.

Also at this time the battery light was flickering, on the scanner it showed roughly 12.5 volts at idle, no electronics were on to create a large drain. Just off idle voltage went up to around 13.4 but dropped again at idle. Battery was reading 12.03 volts yesterday after running it for a half hour the day before and reading 12.6 after shutting it off. Took the battery up and they did a charge and load test on it, came back as good but I have my doubts. It was at 12.68 volts last night when I got home, this morning when I left for work it was 12.5, I will check tonight when I get home also.

I already bought a new battery and will be picking it up tonight as this was the wrong battery type anyway and I just don't trust it as it looks like a cheap reman battery. I am also looking into the alternator rebuild kits, I certainly don't want to drop $300 on an alternator if a $75 rebuild kit will do the same thing.

I am looking into the INPA software and cable, I believe I can use that to look at the individual wheel speed sensors and see if one is messing up. Can I also use this to monitor the turbin and output shaft speed sensors in the transmission? If all of the electrical checks out then I am fairly certain I have a victim of the A clutch failure and at that point I will begin to drop the trans and rebuild it.

Anyone have any other suggestions? I am pretty new to BMW so I don't want to make any fatal mistakes

[RToth]

Looks like it is indeed a failed A clutch assembly, playing around with it this evening and I notice now it is slipping when put in gear, RPMs up to around 1,500 ~ 2,000 and it bangs into gear, every thread I've found with that symptom was always the failed trans. I'll pull the pan off sometime in the next few days and see what I find with metal chunks, I read one place that the input speed or turbine speed sensor will be full of metal debris in the case of the A clutch failure. More updates will follow as I go along, taking my time on it though so updates may come slow haha!

[g300d]

Well looks like you are elbows deep into it already, good luck! Interested to see what you find

[1000hp]

The battery light is for the charging system, ie alternator. NOT the battery itself.
If it is charging to 12.X volts at idle, your alternator is faulty. Low output from the alternator can cause a lot of electrical issues, so start with that.

[RToth]

Originally Posted by 1000hp

The battery light is for the charging system, ie alternator. NOT the battery itself.
If it is charging to 12.X volts at idle, your alternator is faulty. Low output from the alternator can cause a lot of electrical issues, so start with that.

Exactly, but with the drop in voltage overnight with the battery it had in it as well as it being a cheap remanufactured battery and also not even being the correct type for the X5 I replaced it anyway. Alternator will be fixed before I rip into the trans as well and still plan to explore a few other options such as dropping the pan and checking the turbin speed sensor for debris on it indicating the A drum failure. Worst comes to worst I fix the charging system, replace some suspension bushings (I have a hydraulic press) and rebuild the trans and I have an amazingly smooth really nice looking rust free daily driver

[1000hp]

Originally Posted by RToth

Exactly, but with the drop in voltage overnight with the battery it had in it as well as it being a cheap remanufactured battery and also not even being the correct type for the X5 I replaced it anyway. Alternator will be fixed before I rip into the trans as well and still plan to explore a few other options such as dropping the pan and checking the turbin speed sensor for debris on it indicating the A drum failure. Worst comes to worst I fix the charging system, replace some bushings (I have a hydraulic press) and rebuild the trans and I have an amazingly smooth really nice looking rust free daily driver

According to your numbers, it dropped 1.38V overnight. The first reading was taken directly after shutdown.
Dropping 1.38 volts overnight after running all day with a faulty alternator does not indicate an unhealthy battery.

The battery light should be your first big red flag. If the alternator is not producing adequate voltage or amperage while running, you're going to have a lot of issues, regardless of the condition of the battery.
When the engine is running, the battery does very little. After startup, it's basically there to absorb voltage spikes and to take a charge. The vehicle is getting nothing from the battery until the alternator starts to die, like yours is. Replace the alternator and get back to us.

[RToth]

I replaced the battery because I have seen many issues with batteries on the forums, it wasn't terribly expensive and I just didn't trust the one that was in it as well as the one in it was not even the right type of battery, no vent tubes. I didn't replace it thinking it was going to be the fix to it all, the thought had crossed my mind, but I know the alternator would be the root cause of the issue due to the low charge voltage at idle.

I'm not arguing with you, I am very much agreeing with you

I am still hopeful that a good alternator rebuild or replacement will fix the issue, but I am not putting all my eggs in that basket. For now I have it backed into the garage where it will sit for the next several days while I am busy at work and going camping with the family. During this time I will figure out what I want to do with the alternator (rebuild vs replace) and pick up what I need, probably have that all set sometime next week.

[1000hp]

I see.

Is this a water cooled unit? If so, you may have a hard time finding a shop that will rebuild it. If not, a reman. traditional alternator is fairly cheap from the right source. I want to say $150ish?

It's not likely that the alternator issue is causing the trans to free rev, though. That sounds like an internal trans problem. But the alternator may solve multiple other gremlins.

Good luck.

[RToth]

Yes, water cooled. I found a rebuild kit on Amazon for about $80 https://www.amazon.com/Alternator-Re.../dp/B008J7QL3G still looking to see if that will work for me. I do all my work myself, to be honest I just don't trust shops / mechanics. I trust myself with no certifications or any formal mechanical training more then I trust a shop, too many horror stories that I have experienced when I was younger and have heard about from friends, family, and forums Not saying they are all bad, but they are rare in my experience. Also, when I do the work myself I can make sure to take time and put everything back together perfect and clean everything like new rather then just leave a greasy mess everywhere.

[1000hp]

Check out BMW Repair Shops - Find a BMW Mechanic | BimmerShops.com. You can search for BMW-specific shops in your area.
It's good that you are willing and able to tackle the repairs yourself, but sometimes you need to defer to someone with more experience and skill.
Not all shops are rotten. Just a matter of finding the right one.