2010 BMW X6 40d E71

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Jakg

Original Poster:

3,602 posts

175 months

Tuesday 5th March
quotequote all
Had a 335d for the last four years.

Been a great car, bought to be a big family car that was economical to commute in.

A lot changes in four years (i.e. an entire pandemic!) and it wasn't quite hitting the spot any more:
  • we bought an X5 which became primary family car, so no need for massive practicality
  • WFH means no commuting - but most journeys now involve a toddler
  • moved to somewhere a little more rural with worse roads, flooding etc
  • I was bored
I'd been considering something less practical and more exciting (E93 M3 or M135i) but realistically with the above, I'd probably be in the same position again. And I really really like the X5 - but having two of the same car would be weird.

So what's the next best thing? You can guess by now.

Ideal requirements where sunroof, facelift (CIC iDrive), 8 speed gearbox and not too much slower than the 335d.

A couple came and went but were too far to go and see, and then this popped up fairly local...





2010 N57 40d in individual "pearl silver". Always wanted an individual BMW so that's something off the bucket list (even if it's not exactly the best individual colour ever!)

Decent spec with "dynamic package", sunroof, piano black interior and rear heated seats, but not "every option" like the ad claimed.

There is one small catch - it has two gears. Park, and neutral...

Seller claimed car lost drive, they scanned with a generic diagnostic that said the gear lever was faulty, but every garage they spoke to said it wasn't something they had the equipment to resolve.

I thought the gear lever itself was unlikely to be faulty - but it does control whether it's happy to engage drive (e.g. if the door is open, it'll pop it back into park) - so probably a different fault.
I scanned it for faults and the gearbox seemed ok (i.e. no major fault codes, pressures etc in range).

I'm not a big risk taker but I had a good feeling and, well, the good news is it was cheap...

Edited by Jakg on Wednesday 16th October 11:40

Jakg

Original Poster:

3,602 posts

175 months

Tuesday 5th March
quotequote all
So, I paid the money and left with... well nothing obviously. Later on my, delivery arrived.



Just fits in the garage, not fun doing it with manpower alone but it's in and on stands



First job was to remove the grille //M badge and the three (?!) wind deflectors





Next was a new battery - the car came with a spare battery and gear lever the seller bought, but didn't fit after finding out they needed to be coded to the car.

Luckily had the foresight to remove the boot floor etc before it went in the garage, as no access to the boot when tight up to the wall. So all work via the back seat.



Swapping out the 7 year old battery



Didn't fix the fault (unsurprisingly) but gave me a clean slate to clear everything down and rescan it - this car is also newer than I've worked on before so I've had to upgrade diagnostic software (INPA -> ISTA).

Lots of faults, including the gear lever - but interestingly at the very bottom was no communication to the transfer case.

Figured that'd be a good place to start - on earlier cars the controller is in the boot (which is still dismantled), but on later cars it's on the transfer case itself.

So, transfer case propped with a bit of wood



Crossmember removed



Controller removed



Checked all the pins for voltage and all looks good (but don't have the gear to check CAN).

While there the transfer case mount looked a bit worn.

Cut through the metal outer.



Lots of hammering and getting nowhere, eventually removed the centre by drilling through the rubber supports and then could "peel" the mount from the sides



Struggled to get the new one in all the way, refused to buy proper tools so made something out of wood. Wouldn't recommend, but it worked.



If there was voltage at the transfer case controller, I figured it might be dead so was going to buy another (they aren't *that* expensive) but then I remembered the plug came off very easily.

I looked back at the picture when I removed it and noticed the locking tang wasn't in place



Could it be, just not plugged in fully?

Put it back on, cleared the faults and we have communication, gave it a test and...



That's a gear!

After a little longer the traction control had a fit (presumably because it thinks all four wheels are sliding and the car isn't moving), and the transfer case has a warning for oil quality, so a little more work to do before I can drop it on the ground and test it for sure.

I've also put a cable tie through the transfer case plug to ensure the latch stays down to stop this happening again...

Next update could be positive, or very negative!

Until I know it drives (and that I actually like it - I've still not driven one!), I'm holding back doing anything else that needs doing.

Edited by Jakg on Tuesday 5th March 17:12


Edited by Jakg on Monday 14th October 14:29

E63eeeeee...

4,553 posts

56 months

Tuesday 5th March
quotequote all
Fingers crossed for you, I have a bit of a guilty pleasure soft spot for the X6 although I can't imagine ever coming up with a good excuse to buy one.

Mad Maximus

473 posts

10 months

Tuesday 5th March
quotequote all
Proper brave pill stuff this. Great work finding that fault and fingers crossed that’s all.

d_a_n1979

9,668 posts

79 months

Tuesday 5th March
quotequote all
What a great buy this could turn out to be; looks a great motor too wink

Will be following this biggrin

swampy442

1,481 posts

218 months

Tuesday 5th March
quotequote all
I used to hate the X6, but they've aged reall well just like the 6 series.

Good fault diagnosis skills though

Th3 D0n

103 posts

72 months

Friday 8th March
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Great stuff, hope that’s it sorted.
I don’t know why but I’ve always really liked these

Andy665

3,806 posts

235 months

Friday 8th March
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That was a brave move to purchase - no reduction on asking would have covered a replacement gearbox - glad it was a cheap / easy fix

Good to see you prioritising removal of the M badges too

cerb4.5lee

33,615 posts

187 months

Friday 8th March
quotequote all
I'm definitely in for this, and I've always had a soft spot for them. Great to see the wind deflectors/M badge gone too! thumbup

Jakg

Original Poster:

3,602 posts

175 months

Friday 8th March
quotequote all
Jakg said:
After a little longer the traction control had a fit (presumably because it thinks all four wheels are sliding and the car isn't moving), and the transfer case has a warning for oil quality, so a little more work to do before I can drop it on the ground and test it for sure.

I've also put a cable tie through the transfer case plug to ensure the latch stays down to stop this happening again...

Next update could be positive, or very negative!
It's a negative unfortunately - all back together and on the floor and the "no communication" has come back.

It definitely was communicating (temporarily!) so there's something else going on. Time to sleep on it!
Andy665 said:
That was a brave move to purchase - no reduction on asking would have covered a replacement gearbox
A second hand (not refurb) 8HP gearbox is ~£500. I doubt i'd be able to fit that myself, but worst case scenario (if it was just a gearbox) I'd probably still end up ahead.

Edited by Jakg on Monday 14th October 14:29

Jakg

Original Poster:

3,602 posts

175 months

Wednesday 13th March
quotequote all
While I had the car jacked up, I thought it'd be a good idea to replace the brake fluid and all the bleed nipples



Unfortunately the brake fluid reservoir is under the scuttle, and they get fragile with age. Mines been glued together in the past, but the lid had become structural and fell apart when I took it off. Already on the list for replacement, just been moved up a bit. I also got distracted while bleeding and let a load of air in, so need to have another go.



Also noticed one of the "wings" on the front disc backplate was completely loose and touching the disk



Nothing holding it in at all, wouldn't have been good to come off at speed.



Already missing on the other side (and on the X5) so must be a common problem.

Jakg said:
Jakg said:
After a little longer the traction control had a fit (presumably because it thinks all four wheels are sliding and the car isn't moving), and the transfer case has a warning for oil quality, so a little more work to do before I can drop it on the ground and test it for sure.

I've also put a cable tie through the transfer case plug to ensure the latch stays down to stop this happening again...

Next update could be positive, or very negative!
It's a negative unfortunately - all back together and on the floor and the "no communication" has come back.

It definitely was communicating (temporarily!) so there's something else going on. Time to sleep on it!
So I was a bit frustrated that I hadn't fixed it, but mostly I was confused - I was communicating with the transfer case, briefly - what happened?

The voltage with the engine running was a bit high:



I then checked the X5 and got a similar reading so was a bit stumped - but then checked my 335d (which had a new alternator regulator in the last year) and got a reading more like you'd expect (i.e. 14.x v).

I'd seen it suggested that in this scenario, the car shuts down systems and that disconnecting the alternator trigger wire can help - so I tried that, went for a gear and...



In hindsight, I'd jumped the gun a bit here - it wouldn't stay in reverse long enough to climb the (tiny) incline into the garage, so I had to get some help for the push of shame back into the garage.

But it does at least show there's an electrical fault I need to address, most likely the alternator regulator.

The alternators on the top of the engine, so access should be easy - but the tensioner is in the middle, so the fan has to come out to make space to get at it.

And if the fan comes off, some coolant hoses have to come off too, which meant it made sense to address some future jobs a little earlier.

Space made



The cars got the wrong coolant in, so it already needs draining and refilling. I haven't tested the thermostat, but all the diesel cars I've had have had broken thermostats, for £20 I put a new one in to avoid having to redrain later.



The drivers side of the engine has a thick coating of oil, tracked the source back to this boost hose. Common on M57 engines but not found much about the N57.



Some new seals from BMW.



Swapped the regulator on the alternator



Unfortunately no time to test yet though

So to feel like I'd actually fixed something

Battery vent tube had a broken elbow



Replaced



The next update probably won't be on the road (lets not jump the gun again!) - my current theory that the alternators put out too higher voltage and cooked some ECUs.

Edited by Jakg on Thursday 14th March 08:12


Edited by Jakg on Monday 14th October 14:29

BrettMRC

4,468 posts

167 months

Wednesday 13th March
quotequote all
Excellent work OP!

Like many others I've a soft spot for these!

Mad Maximus

473 posts

10 months

Wednesday 13th March
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Sounds like you’re getting there. It’ll feel so good once it’s fixed.

salmanorguk

213 posts

99 months

Monday 18th March
quotequote all
Jakg said:
The next update probably won't be on the road (lets not jump the gun again!) - my current theory that the alternators put out too higher voltage and cooked some ECUs.

Edited by Jakg on Thursday 14th March 08:12
Really enjoying reading about this. Its weird how the original X6 design now seems okay thanks to the fussy new designs!

Also I hope you dont mind but I couldnt resist:


https://i.imgflip.com/8jn7gv.gif

Pent

286 posts

26 months

Tuesday 19th March
quotequote all
this is a good methodical approach i like it
keep it coming

Its Just Adz

15,018 posts

216 months

Tuesday 19th March
quotequote all
Really interesting thread this OP.

I like the X6 too, they don't half get some stick but they drive so bloody well.

Jakg

Original Poster:

3,602 posts

175 months

Monday 25th March
quotequote all
(this is a boring update, it still doesn't drive)

Jakg said:
The voltage with the engine running was a bit high:

With the new regulator, voltage is looking much better



The engine bay partition / scuttle panel are a common fault for disintegrating, mine had been previously repaired with glue but fell to bits when I was bleeding the brakes



Aftermarket ones are only £25.

When broken, water can drain off onto the engine instead, typically collecting around the injectors and causing issues. The aftermarket parts didn't have any weatherstripping unlike the genuine ones, something like butyl rubber is probably the right thing for the job but silicone sealant works fine and is what I had...



All back together and good as new



As part of this the pollen filter came out, too disgusting to go back in



There's an additional filter for the recirculated air on the inside as well, looked clean until I opened it up and you can see the fold at the bottom shows the filter is meant to be white!



While working on the car I also noticed both disc backplates were loose - some penny washers later and secured



Getting to the backplates required removing the caliper carriers, which were way overtightened. I was using a 3/8" adaptor for the socket and snapped two before eventually getting it undone with a 3/8" breaker bar and a trolley jack to get it started. Unfortunately found I had a 1/2" (so no adaptor required) when I went to buy one afterwards...



Edited by Jakg on Monday 14th October 14:29

nismo48

4,440 posts

214 months

Tuesday 26th March
quotequote all
Good luck with the project, some proper elbow grease needed there wink

Stedman

7,287 posts

199 months

Tuesday 26th March
quotequote all
Great thread

JakeT

5,627 posts

127 months

Tuesday 26th March
quotequote all
While I’m not a diesel, and not an X6 fan this is a good project. I’d be inclined to say the gearbox was okay too, as ZF 8HPs rarely go wrong, hence them being quite cheap.