35i & 35is common failures / buyer check points

[ph001]

Hey all,

Spent the best part of 2 days reading this forum in attempt to glean as much info as I can on my prospective 35i / 35is purchase.

So far I have ascertained the following as known issues (although not necessarily particularly prevalent). I have listed in order of most expensive to least (assuming car does not have a warranty):

• DCT gearbox rattle / failure

Only aware of 2 or 3 instances where owners have had these replaced under warranty. Rattling / noisy seems to be the complaint. Dread to think what one would cost out of warranty.

• Cracked alloys

A common occurrence on the 296 (1st pic), less common on the 326M (2nd pic) style alloy wheels but all the 19" seem to be affected much more then the 18". Cracking is typically on the inside rim so not easy to spot from the roadside. Ditching the RFT (run flat tyres) may help to prevent cracking as the runflats have a very stiff side wall. Budget at least £500 per wheel if you have to fund it yourself, or repair may be an option for £50-£70 each if you want to keep 'em.

• Piezo injector failure

These seem to leak fuel when closed which commonly causes poor running, particularly poor starting from cold with lots of spluttering. Looking at least £200 x 6 + fitting. BMW seemed to have revised these as the years have gone by so the most recent ones may be more reliable.

• Leaking adaptive suspension

Seems to be fairly isolated but one or two have had shock absorbers replaced due to fluid leakage so inspect carefully with the wheel removed if your warranty is coming to an end. Noises / clunks from the suspension also reported but these seem to be more likely to be bushes on the rear anti-roll bar.

• HPFP (High pressure fuel pump)

Most common complaint for this seems to be noisy rather than actually failing and stopping the car. Not sure of exact price but not cheap!

• Faulty coil packs

A common failure point on many cars (not just BMW) and it seems the E89 is not excluded. Not a difficult DIY to replace and I think around £60 or so each. Misfire on acceleration and poor performance once warmed up seem the most common complaint.

• LPFP (low pressure fuel pump)

The E89 uses a 'primer pump' inside the tank to send fuel up to the HPFP. You can often hear it start when you turn on the ignition. Again, seems like noise issues are the most prevalent complaints. Most dealers seem to needlessly change these when trying to fix cold start problems, only to then find it was the injectors all along.

• Rattling wastegate actuators

Again, not sure how this manifests itself in terms of fault symptoms but fairly widely reported. There are also some pressure transducers and a filter related to the turbo which have been noted to fail and cause an overboost malfunction (EML light on dash) - see here http://www.z4-forum.com/forum/viewtopic.php?f=45&t=87475
Not sure of the fix for the wastegate, maybe just an annoyance rather than a problem?

• Electric handbrake failure

Usually lock on and can't be released which makes it a bugger to get the car to a garage. Seems to be related to early 'buggy software' in connection with the wheel speed sensor which perhaps isn't very well written. New software flash of the handbrake ECU seems to sort it. Most have to physically remove the electric actuators (small servo motors on the rear hub) to be able to move the car :-(

• Water ingress into boot / rear light cluster

VERY common reported fault and of course not restricted to the 35i. The BMW sealant degrades badly at around 5 yrs or so and requires all the rear sealant strip around the boot to be removed, cleaned, gutter sealant added and refitted. The rear light cluster seal also seems badly designed, resulting in misting and corrosion inside the assembly. Aftermarket ones are available from Euro Car Parts for a modest amount and seem to be better designed, otherwise it's a strip down, clean and seal properly before refitting. Note there was a recall for some aspects of water ingress into this area (vents?), and you can tell if this has been done by the presence of a green trim clip in the boot area.



I think that's all the stuff I've read about. Please feel free to add / comment and correct if I got anything wrong or missed anything.

 

[Zed Five]

Fingers crossed, I've not experienced any of these and am now up over 40k miles

Biggest failure for a 35iS is to adhere to national speed limits. :wink:

 

[metal licker]

Had my 35i two+ years had none of the above but it will probable get one or two now I've mentioned it 8)

 

[stuartinzg]

None of the above for me either. Now at 35k (from 18k when bought).

 

[Nanu]

Fingers crossed, I've not experienced any of these and am now up over 40k miles

Biggest failure for a 35iS is to adhere to national speed limits. :wink:

Yep just the same, no faults but as said, national speed limits are definitely an issue :rofl:

 

[sammyz]

My parking brake 'failed' with warning lights but was working fine. So it seems it can fail and stick on or fail but still function. Updated software cured this.

 

[craig3.2]

My parking brake 'failed' with warning lights but was working fine. So it seems it can fail and stick on or fail but still function. Updated software cured this.

Good to see it was an easy fix John

 

[ph001]

Great to see many owners up around the 40k miles mark with none of the above. Shows that it is quite a reliable car generally. I am quite surprised about the water ingress not being apparent as this is very widely reported. One to keep your eye on I think - it's a pretty cheap simple fix anyway.

Does anybody have any more info or experience of the rattling wastegate issue?

 

[Wrs]

Does anybody have any more info or experience of the rattling wastegate issue?

Maniac does I believe and replacement exhausts.

You have missed 296 & 326 alloys cracking, very widely reported and £600 a pop.

 

[ph001]

Oh yes, the alloys, good spot. Have added - thank you.

 

[chasBMW]

Sadly roof failure due to microswitches/sensor can occur

 

[Z4M-2006]

The wastegates rattle on the N54 due to the actuator wearing..
You can have this altered by moving the base setting and this "tightens " the wastegate rod..
It's a work around and can cause the odd running issue..
Only real fix is too replace turbo's .. big money.

The adaptive suspension legs can leak on the front and they are expensive to replace ..

I did around 6k in my 35is and sold it with 65k (ish) on it and in my ownership it was faultless..

It got faster as the miles ticked up.


I think a warranty is a good thing to have on the 35is as the engine bills can be ruinous ..

 

[JustCruzin]

Had a rear cracked 326 on my now sold 35is replaced very fortunately under warranty

Cheers JC

 

[R.E92]

Had my car for nearly 3 years, from 17k to 60k miles and had the following:

Piezo injector failure

Leaking adaptive suspension

HPFP (High pressure fuel pump)

Faulty coil packs

LPFP (low pressure fuel pump)

Rattling wastegate actuators


The HPFP will cause the car to misfire while driving and to crank for long while starting. When it gets more severe will prevent the car starting. A bad HPFP will also mean your engine runs lean which is bad news.

The rattling wastegates are just an annoyance for the most part, all cars over 50k miles will have it to a varying degree, it's hard to hear from the drivers seat unless you part in a garage. They will eventually fail but it takes a good 30k miles before you start to notice a lack of boost and the car throws a fault.

Coil packs can be picked up for £20 each if you shop around. I got a fresh set of 6 for £120 from ECP during their last black friday sale.

Injectors are another thing that will be knackered on most cars if they are revision 11 or lower but are only really obvious once you have them fixed. When they fail the car will need recovering but they can run in a leaky state for years. It's only once you get a new set of injectors that you realise how much smoother and more fuel efficient the car is.


The DCT gearbox has proven to be incredibly reliable all across the BMW range. As with most things in these cars it's been hugely over-engineered, capable of handling much more torque than a standard Z4 can throw at it.

 

[stuartinzg]

Had my car for nearly 3 years, from 17k to 60k miles and had the following:

Piezo injector failure

Leaking adaptive suspension

HPFP (High pressure fuel pump)

Faulty coil packs

LPFP (low pressure fuel pump)

Rattling wastegate actuators


The HPFP will cause the car to misfire while driving and to crank for long while starting. When it gets more severe will prevent the car starting. A bad HPFP will also mean your engine runs lean which is bad news.

The rattling wastegates are just an annoyance for the most part, all cars over 50k miles will have it to a varying degree, it's hard to hear from the drivers seat unless you part in a garage. They will eventually fail but it takes a good 30k miles before you start to notice a lack of boost and the car throws a fault.

Coil packs can be picked up for £20 each if you shop around. I got a fresh set of 6 for £120 from ECP during their last black friday sale.

Injectors are another thing that will be knackered on most cars if they are revision 11 or lower but are only really obvious once you have them fixed. When they fail the car will need recovering but they can run in a leaky state for years. It's only once you get a new set of injectors that you realise how much smoother and more fuel efficient the car is.


The DCT gearbox has proven to be incredibly reliable all across the BMW range. As with most things in these cars it's been hugely over-engineered, capable of handling much more torque than a standard Z4 can throw at it.

I should probably start to prepare myself for some of these - being at 35k now.

Did you go with OEM injectors or look at aftermarket alternatives like the coils? Same for the HP/LPFP.

What did you do about the wastegates? I had an idea to go hybrid when they need doing and get them re-engineered. What do you think?

The leaking adaptive is a worry as that's bloody expensive and I'm out of warranty.

 

[R.E92]

Had my car for nearly 3 years, from 17k to 60k miles and had the following:

Piezo injector failure

Leaking adaptive suspension

HPFP (High pressure fuel pump)

Faulty coil packs

LPFP (low pressure fuel pump)

Rattling wastegate actuators


The HPFP will cause the car to misfire while driving and to crank for long while starting. When it gets more severe will prevent the car starting. A bad HPFP will also mean your engine runs lean which is bad news.

The rattling wastegates are just an annoyance for the most part, all cars over 50k miles will have it to a varying degree, it's hard to hear from the drivers seat unless you part in a garage. They will eventually fail but it takes a good 30k miles before you start to notice a lack of boost and the car throws a fault.

Coil packs can be picked up for £20 each if you shop around. I got a fresh set of 6 for £120 from ECP during their last black friday sale.

Injectors are another thing that will be knackered on most cars if they are revision 11 or lower but are only really obvious once you have them fixed. When they fail the car will need recovering but they can run in a leaky state for years. It's only once you get a new set of injectors that you realise how much smoother and more fuel efficient the car is.


The DCT gearbox has proven to be incredibly reliable all across the BMW range. As with most things in these cars it's been hugely over-engineered, capable of handling much more torque than a standard Z4 can throw at it.

I should probably start to prepare myself for some of these - being at 35k now.

Did you go with OEM injectors or look at aftermarket alternatives like the coils? Same for the HP/LPFP.

What did you do about the wastegates? I had an idea to go hybrid when they need doing and get them re-engineered. What do you think?

The leaking adaptive is a worry as that's bloody expensive and I'm out of warranty.

I've gone with OEM parts.
For coils there are a few different brands of OEM coil. Bosch, Deplhi and Eldor. There's no real evidence to suggest Delphi or Eldor are any better than Bosch and the Bosch coils were £60 cheaper for the lot.

With injectors I'm not aware of any aftermarket solutions. The index 12 seem to be a more robust design as I'm not aware of any failures.

For turbos there are a good few aftermarket options. Mine were replaced under warranty so I just have another OEM set. If you are doing it out of your own pocked then Pure offer some good setups but I think most retain the stock wastegate configuration so may also suffer rattle. If you don't plan on going above 500bhp then stock are all you need.

Leaking dampers are just a fact of life with the adaptive suspension. I've seen lots of people reporting leaks and there is a serious part shortage of them due to that. 2 week lead time from dealers.

 

[stuartinzg]

Had my car for nearly 3 years, from 17k to 60k miles and had the following:

Piezo injector failure

Leaking adaptive suspension

HPFP (High pressure fuel pump)

Faulty coil packs

LPFP (low pressure fuel pump)

Rattling wastegate actuators


The HPFP will cause the car to misfire while driving and to crank for long while starting. When it gets more severe will prevent the car starting. A bad HPFP will also mean your engine runs lean which is bad news.

The rattling wastegates are just an annoyance for the most part, all cars over 50k miles will have it to a varying degree, it's hard to hear from the drivers seat unless you part in a garage. They will eventually fail but it takes a good 30k miles before you start to notice a lack of boost and the car throws a fault.

Coil packs can be picked up for £20 each if you shop around. I got a fresh set of 6 for £120 from ECP during their last black friday sale.

Injectors are another thing that will be knackered on most cars if they are revision 11 or lower but are only really obvious once you have them fixed. When they fail the car will need recovering but they can run in a leaky state for years. It's only once you get a new set of injectors that you realise how much smoother and more fuel efficient the car is.


The DCT gearbox has proven to be incredibly reliable all across the BMW range. As with most things in these cars it's been hugely over-engineered, capable of handling much more torque than a standard Z4 can throw at it.

I should probably start to prepare myself for some of these - being at 35k now.

Did you go with OEM injectors or look at aftermarket alternatives like the coils? Same for the HP/LPFP.

What did you do about the wastegates? I had an idea to go hybrid when they need doing and get them re-engineered. What do you think?

The leaking adaptive is a worry as that's bloody expensive and I'm out of warranty.

I've gone with OEM parts.
For coils there are a few different brands of OEM coil. Bosch, Deplhi and Eldor. There's no real evidence to suggest Delphi or Eldor are any better than Bosch and the Bosch coils were £60 cheaper for the lot.

With injectors I'm not aware of any aftermarket solutions. The index 12 seem to be a more robust design as I'm not aware of any failures.

For turbos there are a good few aftermarket options. Mine were replaced under warranty so I just have another OEM set. If you are doing it out of your own pocked then Pure offer some good setups but I think most retain the stock wastegate configuration so may also suffer rattle. If you don't plan on going above 500bhp then stock are all you need.

Leaking dampers are just a fact of life with the adaptive suspension. I've seen lots of people reporting leaks and there is a serious part shortage of them due to that. 2 week lead time from dealers.

Might be worth going fully adjustable KW V3 with EDC delete at that point then.
Won't the OEM turbo's fail again? or has it been revised as well?

 

[R.E92]

Might be worth going fully adjustable KW V3 with EDC delete at that point then.
Won't the OEM turbo's fail again? or has it been revised as well?

I expect they will start rattling again in 40k miles, I don't think the turbo design ever changed.
I'll probably be driving another car by then though, had the Z4 for close to 3 years already, might keep it another year or two since I love it so much.

The rattle isn't too bad an can be masked by changing the resting wastegate position in the DME. This will increase lag a little though.

The consensus amongst the tuning community is that OEM turbos are the most reliable. An unsettling amount of aftermarket turbos fail before hitting 30k miles.

 

[stuartinzg]

Might be worth going fully adjustable KW V3 with EDC delete at that point then.
Won't the OEM turbo's fail again? or has it been revised as well?

I expect they will start rattling again in 40k miles, I don't think the turbo design ever changed.
I'll probably be driving another car by then though, had the Z4 for close to 3 years already, might keep it another year or two since I love it so much.

The rattle isn't too bad an can be masked by changing the resting wastegate position in the DME. This will increase lag a little though.

The consensus amongst the tuning community is that OEM turbos are the most reliable. An unsettling amount of aftermarket turbos fail before hitting 30k miles.

Thought about this kit?
http://turbolabofamerica.com/bmw-135i-535i-335i-turbo-wastegate-rattle-repair-fix/

 

[R.E92]

Might be worth going fully adjustable KW V3 with EDC delete at that point then.
Won't the OEM turbo's fail again? or has it been revised as well?

I expect they will start rattling again in 40k miles, I don't think the turbo design ever changed.
I'll probably be driving another car by then though, had the Z4 for close to 3 years already, might keep it another year or two since I love it so much.

The rattle isn't too bad an can be masked by changing the resting wastegate position in the DME. This will increase lag a little though.

The consensus amongst the tuning community is that OEM turbos are the most reliable. An unsettling amount of aftermarket turbos fail before hitting 30k miles.

Thought about this kit?
http://turbolabofamerica.com/bmw-135i-535i-335i-turbo-wastegate-rattle-repair-fix/

I've heard about revised wastegate designs but I've not seen anyone going into details about using them.

I would imagine the cost to remove turbos and replace the wastegates might be quite high already. I don't think it's just a case of bolting new wastegates on, you need to cut and weld.

With warranty BMW will just replace the turbos as soon as they start to rattle. Without warranty you may as well go large and get some bigger turbos