[CuntFace5000]

Hello,

Had my 335d xdrive in for an engine oil change today and they noticed a significant oil leak from what looks like the transfer box.

They said further investigation was needed, however I now have a third party warranty so I can't use main dealers to carry out the work. I will have to get an independent specialist to diagnose and repair.

The car has only done 27,000 miles. The BMW dealer said it was very unusual for an oil leak like this with a low mileage car. They also said 9 times out of 10 it is just a seal.

What worries me though is if there is a reason for the seal failing like a worn shaft, splines or a bearing on it's way out.

The reason I'm worried is because thinking about it when at cruising speeds, say a steady 70mph, there would sometimes be a low frequency droning noise that would come and go. The noise would build up to it's peak (which wasn't very loud) then get quieter then within a second or so the noise would cycle again. Say 1 cycle of noise every 2 seconds.

I am hoping it is just a seal that needs replacing and that the noise was unrelated. However my gut tells me there is an expensive repair bill heading my way.

I would be grateful if anyone who has had, or knows of, a similar issue could share their experience.

[CuntFace5000]

Picture 1

[Wills2]

Is it remapped?

[CuntFace5000]

Picture 2

[CuntFace5000]

Picture 3 sorry for the poor picture quality I had to take it from my laptop screen

[CuntFace5000]

Originally Posted by Wills2

Is it remapped?

It is. Done by DMS. But I really don't abuse the car as is reflected by it returning 42mpg.

[Wills2]

Originally Posted by demc1982

It is. Done by DMS. But I really don't abuse the car as is reflected by it returning 42mpg.

Just thinking about your warranty, the car is being run over the torque limits of the gearbox.

[Watsey]

Originally Posted by Wills2

Just thinking about your warranty, the car is being run over the torque limits of the gearbox.

Not necessarily.

DMS will remap only up to the gearbox torque limit if requested, as many people do (me included).

This is really the default outcome as, unless DMS is spoofing the ECU output data, the TCU and the ECU operate in a real-time feedback loop. If the ECU output data indicates that the torque limits are being exceeded the TCU intervenes to reduce the power/torque being produced by the engine.

Two independent dynos have shown that my 30d produces a max of 678 to 711Nm, which is nicely around the official max rating of 700Nm.

Even allowing for a very modest engineering safety tolerance of 10% these AT should be safe and reliable to the high 700sNm.

Most likely it's just a seal, unless the car has been 'launched' repeatedly.

[Wills2]

Originally Posted by Watsey

Not necessarily.

DMS will remap only up to the gearbox torque limit if requested, as many people do (me included).

This is really the default outcome as, unless DMS is spoofing the ECU output data, the TCU and the ECU operate in a real-time feedback loop. If the ECU output data indicates that the torque limits are being exceeded the TCU intervenes to reduce the power/torque being produced by the engine.

Two independent dynos have shown that my 30d produces a max of 678 to 711Nm, which is nicely around the official max rating of 700Nm.

Even allowing for a very modest engineering safety tolerance of 10% these AT should be safe and reliable to the high 700sNm.

Most likely it's just a seal, unless the car has been 'launched' repeatedly.

Good luck with that speaking to a warranty company if it went bang...I think they'd tell you to FRO as would BMW.

I'm sure DMS would stand on though....

[CuntFace5000]

DMS said the remap was undetectable. They also said if there was ever any need to remove for a possible warranty claim scenario then they would remove it FOC.

I didn't ask for any torque limits to be removed. They only remapped the ECU and left the gearbox alone.

I have never launched the car, although I can't vouch for the previous owner.

[Eddamoo]

Banging on about a remap isn't really helpful to the op to be fair. Nor would it cause an oil leak in 99.9 percent of cases.

That oil looks to be leaking around the transmission sump, not the transfer case. The transmission sumps are known to warp in some cases. I would get the sump and oil changed, but a specialist transmission shop will sus it out easily!

[CuntFace5000]

Originally Posted by Eddamoo

Banging on about a remap isn't really helpful to the op to be fair. Nor would it cause an oil leak in 99.9 percent of cases.

That oil looks to be leaking around the transmission sump, not the transfer case. The transmission sumps are known to warp in some cases. I would get the sump and oil changed, but a specialist transmission shop will sus it out easily!

Thanks,

That's a good call about taking it to a dedicated transmission specialist

[Watsey]

Originally Posted by Wills2

Good luck with that speaking to a warranty company if it went bang...I think they'd tell you to FRO as would BMW.

I'm sure DMS would stand on though....

Where did I state that the warranty would be unaffected ?

You made a statement that the gearbox is being run beyond its limits.

That's not necessarily the case (if you understood the feedback loop between the ECU and TCU), and it's unlikely to be the cause of the fluid weep that the OP's car has. A remap is very unlikely to cause the AT casing to warp.

[bishbosh]

Looks more like the gearbox sump to me too. If it's been leaking fluid that could explain the whine.

A new sump, bolts and fluid fitted at a transmission specialist is around £350 - £380.

[Watsey]

OP - unless you have a 'maxed' remap from DMS and/or abuse the drivetrain (launch control) this is very unlikely to be a symptom of the remap.

Engine and gearbox sumps can weep, and there's usually a very simple (and easy to fix) reason for it.

IF a bigger problem was discovered, having a 3rd party warranty could put you in a better position than if the warranty was with BMW.

The warranty provider is (my assumption) less likely to require a full ECU/TCU diagnostic from BMW and a BMW dealer is less likely to do it in this situation because finding anything untoward may mean the job is refused and it wouldn't earn that income.

If a BMW dealer was applying to BMW UK for warranty reimbursement for a major drivetrain component replacement then a data diagnostic is perhaps more likely.

Remaps are detectable, but whether someone decides to go looking is a different matter.

[CuntFace5000]

Thanks fellas,

It's booked in at BMW for an investigation on the 3rd of February. £84. I know they'll probably just get it up on the ramps, give it a wipe and try to spot the source but it's a start at least. If they quote me say £300 to £400 for a repair I will just pay it. Anymore than that and I'll take it to a transmission specialist and claim back off the warranty.

If BMW say they need to strip anything down to look for a root cause then I will have another decision to make.

[CuntFace5000]

Originally Posted by Watsey

OP - unless you have a 'maxed' remap from DMS and/or abuse the drivetrain (launch control) this is very unlikely to be a symptom of the remap.

Engine and gearbox sumps can weep, and there's usually a very simple (and easy to fix) reason for it.

IF a bigger problem was discovered, having a 3rd party warranty could put you in a better position than if the warranty was with BMW.

The warranty provider is (my assumption) less likely to require a full ECU/TCU diagnostic from BMW and a BMW dealer is less likely to do it in this situation because finding anything untoward may mean the job is refused and it wouldn't earn that income.

If a BMW dealer was applying to BMW UK for warranty reimbursement for a major drivetrain component replacement then a data diagnostic is perhaps more likely.

Remaps are detectable, but whether someone decides to go looking is a different matter.

Regarding the remap I just asked for the one advertised as 395bhp. Because I live in Cheshire and they're based in Southampton they came to me and done it on my drive. No rolling road custom maxed out map. Although they did say I am entitled to a rolling road session either at Southampton or their Midlands depot inclusive of the price.

But honestly I don't thrash it very often at all. It's just nice to finally be able to overtake safely after years of driving a 1.8 Toyota avensis

[CuntFace5000]

Had the car back from BMW today. They said there are actually 2 oil leaks.

1 from the transmission sump. Quoted nearly a grand to basically fit a new sump gasket. £441 of this was for new transmission fluid.

The 2nd leak is coming from the transfer case. They said it looks like someone has had it apart at some point. It is leaking from the 2 mating faces of the case. They said there isn't a seal or gasket here and that it is a sealed unit. They would only fix it buy replacing the transfer case for £2521.

[CuntFace5000]

Some pictures of the leak from the transfer case

[Watsey]

Who did you buy the car from, and when ? (date & mileage)

Transfer cases are a known problem on units like the 328d. Maybe there's a similar latent defect across the xDrive range ?

Obviously that's s big bill, combined, which would be good to have recourse (claim) for.

[CuntFace5000]

Originally Posted by Watsey

Who did you buy the car from, and when ? (date & mileage)

Transfer cases are a known problem on units like the 328d. Maybe there's a similar patent defect across the xDrive range ?

Obviously that's s big bill, combined, which would be good to have recourse (claim) for.

I bought it from an independent dealer on 28th October 2019, the car had covered 24k. It has done just under 28k now. I imagine they'll say sold as seen. I bought it using Close Brothers Motor Finance on a PCP deal. I will maybe call them to see what they suggest although I would like to get as much advice as possible first.

[CuntFace5000]

Can see from the second picture it. Looks like some kind of flexible sealant that has been used. Obviously not OEM.