E89 35i sump oil leak

[Riche89]

Hi I wonder if you can help me. I just found an oil leak from the back of my sump on my 35i dct.
Went for a 150 mile round trip at the weekend which I averaged 41 MPG mostly all motorway miles. No problems at all everything running fine then the next day went to start up and the orange oil can came on and it looks like I've lost three quarters of a litre of oil from the bottom of the sump as I can see the oil has sprayed backwards underneath.
Anyone know the rough cost of replacing this gasket and where I could go near Maidenhead, Berkshire for a good independent garage as I can't leave it like this.
Thanks all. Rich

[R.E92]

First make sure that the leak is coming from the sump. It could be a cracked valve cover leaking down the back of the engine.

Sump gasket leaks aren't usually that severe. On the 335i the sump gasket change requires the subframe to be dropped and is quite a lot of work, hopefully the Z4 is easier.

[Riche89]

Thanks for that. Yes will try to look at the back of the block tomorrow.

[Mr Tidy]

Definitely worth cleaning everything up to see where it is really coming from.

My 3 Series got an advisory for an oil leak last year and the tester said it was coming from the back of the engine.

But I knew there was a leak from the oil filter housing and decided to leave it until it was due a service which has now been done.

With the undertray in place I suspect he saw oil at the back of the undertray.

[mcbutler]

First make sure that the leak is coming from the sump. It could be a cracked valve cover leaking down the back of the engine.

Sump gasket leaks aren't usually that severe. On the 335i the sump gasket change requires the subframe to be dropped and is quite a lot of work, hopefully the Z4 is easier.

Had one on my 23i, went round and nipped up as amny of the bolts as I could reach, several were almost finger tight!!!
Fixed it though so worth a try

[Riche89]

That's a great idea I will check the bolts. if I can squeeze under the car.ha