Slight rear diff leak

[Stevey101]

Hello everyone

So at the weekend I bought a F83 M4 competition. The car it self runs perfect, only done 30k miles and is very clean with a full bmw service history with receipts. Now on further inspection a few days after I’ve noticed I’ve got a very slight diff leak, it’s not trickling or pouring out but the area is kind of moist so it’s not like a big leak and it runs perfect. To my knowledge anyway as I’m not a mechanic and only know very basic things.
Now what’s strange and the dealer did mention this when I told him about the leak, it only had its last service back in July 24 ( I have all paperwork and can see this) and on that service it specifically had a rear diff service so I don’t get how 11m later it can be slightly leaking. Obviously I know and am going to take to garage to inspect it but I’m just wanting a bit of advice.
I do have the crappy 6m 3rd party warranty which only covers mechanic labour costs up to £50ph and the dealer I bought it off basically told me when buying “ just make sure you’re happy with it check it all throughly because you once it’s sold I won’t be getting it back or liable for any issues “ blah blah which I know legally isn’t the case. Hopefully it doesn’t get to that and it’s just a minor fix as the car honestly is one of the cleanest M4s I’ve ever seen it’s beautiful with all official BMW service history. Drives great it’s literally just this slight leak.

Thanks

[paddy1970]

You're absolutely right that the dealer's "sold as seen" disclaimer doesn't override your consumer rights. Under the Consumer Rights Act 2015, you have protection for up to 6 months where the burden of proof is on the dealer to show any fault wasn't present at sale.

Get the car inspected by a BMW specialist or independent garage ASAP to establish the cause and get a written report

[Stevey101]

paddy1970 said:

You're absolutely right that the dealer's "sold as seen" disclaimer doesn't override your consumer rights. Under the Consumer Rights Act 2015, you have protection for up to 6 months where the burden of proof is on the dealer to show any fault wasn't present at sale.

Get the car inspected by a BMW specialist or independent garage ASAP to establish the cause and get a written report

Yeah exactly mate I’m going to, I just hope it’s nothing major as I really can’t be bothered with the hassle of trying to get the dealer to pay up as I know he’s going run as fast as he can 🤣

[stevemcs]

Isn't it just the nose seal on the diff that leaks - the same as all BMW's

[Stevey101]

stevemcs said:

Isn't it just the nose seal on the diff that leaks - the same as all BMW's

Yeah, the dealer said it’s probably just the seal/cap and it’d nothing at all, nothing big and I could drive with it for the next few years no issues. I don’t personally believe him as such and I’d rather not have a leak. This is why I’m asking as I want to know it’s a common thing and anything to worry about?

[stevemcs]

Yes its common, I think the last one we did was around an hour plus the seal. They usually sweat and a little oil goes a long way.

You could always top the oil up, clean the diff down and see what happens

[Stevey101]

stevemcs said:

Yes its common, I think the last one we did was around an hour plus the seal. They usually sweat and a little oil goes a long way.

You could always top the oil up, clean the diff down and see what happens

Thanks a lot for the advice, appreciated. Also what’s best oil for this car?

[stevemcs]

Just go genuine, its not usually all that expensive and you won't need much

[Stevey101]

stevemcs said:

Just go genuine, its not usually all that expensive and you won't need much

I was told Shell Helix ultra 5W30?

[stevemcs]

Sorry, for the diff oil - it will be specific, for engine oil, BMW tend to brand stuff but its usually Shell, we use Qauntum (Fuchs) but i'm always a fan of Shell.

[TheWokeBlob]

I've heard those diffs do like to leak when overfilled so might just need a bit draining off.

Firstly contact the dealer and see what if anything he is purposing to do - You can't spend his money for him, so you can't really drop it into a garage expecting him to eventually foot the bill without letting him know

If he's being awkward you've got the choice to either try and go legal, which you'll probably win, eventually, but it's really worth bearing in might that it is a costly and lengthy process and it is a risk, so best to save that as a last case scenario and hopefully working with the dealer to get a resolution.

[Stevey101]

stevemcs said:

Just go genuine, its not usually all that expensive and you won't need much

[Trevor555]

Stevey101 said:

the dealer I bought it off basically told me when buying just make sure you re happy with it check it all throughly because you once it s sold I won t be getting it back or liable for any issues

I'd be very concerned about what else might be wrong.

Get that car thoroughly checked now.

Mileage genuine?

Poor accident repair?

Vin numbers all ok?

Damage underneath?

Dodgy, stupid, dealer who says that is hiding something.

[Lester H]

Stevey101 said:

Hello everyone

So at the weekend I bought a F83 M4 competition. The car it self runs perfect, only done 30k miles and is very clean with a full bmw service history with receipts. Now on further inspection a few days after I ve noticed I ve got a very slight diff leak, it s not trickling or pouring out but the area is kind of moist so it s not like a big leak and it runs perfect. To my knowledge anyway as I m not a mechanic and only know very basic things.
Now what s strange and the dealer did mention this when I told him about the leak, it only had its last service back in July 24 ( I have all paperwork and can see this) and on that service it specifically had a rear diff service so I don t get how 11m later it can be slightly leaking. Obviously I know and am going to take to garage to inspect it but I m just wanting a bit of advice.
I do have the crappy 6m 3rd party warranty which only covers mechanic labour costs up to £50ph and the dealer I bought it off basically told me when buying just make sure you re happy with it check it all throughly because you once it s sold I won t be getting it back or liable for any issues blah blah which I know legally isn t the case. Hopefully it doesn t get to that and it s just a minor fix as the car honestly is one of the cleanest M4s I ve ever seen it s beautiful with all official BMW service history. Drives great it s literally just this slight leak.

Thanks

Glad you are happy with the rest of the car and can I can understand your distaste for a lot of hassle. Incidentally, how many cars are happily running round with slight oil leaks, or what MOT testers love to call ‘ slight misting’ on shock absorbers? I look at quite a number of MOT histories, sad, I know ,and sometimes a car has had these faults for years!

[Stevey101]

Trevor555 said:

Stevey101 said:

the dealer I bought it off basically told me when buying just make sure you re happy with it check it all throughly because you once it s sold I won t be getting it back or liable for any issues

I'd be very concerned about what else might be wrong.

Get that car thoroughly checked now.

Mileage genuine?

Poor accident repair?

Vin numbers all ok?

Damage underneath?

Dodgy, stupid, dealer who says that is hiding something.

Car has been fully HPI checked etc and I have got all genuine receipts from BMW for service history. Car is clean underneath (from a basic viewing) and drives perfect from what I can see. You’re right though something does feel off about it all.

[Trevor555]

I'm worried for you.

The dealer said that for a reason.

[culpz]

As other have said, I think this can be normal. My E92 went into a dealer for a recall and they logged it as a "leaking" rear diff. Specialist said it's absolutely fine and is measuring at the correct level. These can just show excessively damp, but it's not leaking, per se.

[Stevey101]

culpz said:

As other have said, I think this can be normal. My E92 went into a dealer for a recall and they logged it as a "leaking" rear diff. Specialist said it's absolutely fine and is measuring at the correct level. These can just show excessively damp, but it's not leaking, per se.

Yeah could be so as like I say it’s not dripping or pouring out it’s more damp

[Stevey101]

• UPDATE*

So I got these pics of it today. I saw a mechanic for a brief check and he thinks it’s the shaft seal. According to him “ it’s leaking a lot” but to me it doesn’t seem much at all.
Anyway I’m going to get fixed but just need to wait for my warranty policy to update to my private reg so I’m just wondering if it’ll be okay to drive here and there?

[stevemcs]

Yes that’s leaking, damp is just that but that’s dripping.