Fluid leak coming onto the fuel tank

[InterlagosMC]

Hi guys, what lines run above the fuel tank on our cars as I found damp patches on both outer edges of the fuel tank and a large amount of fluid on lines running above the fuel tank, I know it’s not the rear diff at all as I only changed the front input seal about 18 months ago and that area is dry.

My car is an m coupe if that makes any difference

Thanks

[j3nks79]

Brake pipes

[Mr Tidy]

That could be it, the pipe to the driver's side rear brake runs across the bulkhead behind the fuel tank, although if that is leaking that much it would probably be pretty obvious driving it!

I'm not sure if the Coupe has any roof drains in that area?

[InterlagosMC]

I did think brake lines but when I checked the ends of the hard lines they all look in good condition, it’s not water as it leaves a residue with clumps with the dirt. I’m going to keep checking the brake fluid reservoir for a drop in level and will keep an eye on the fuel gauge as I barely drive the car. I’m doing a subframe rebuild in the summer so I can properly investigate it then. I was wondering if it’s the fuel filter seal weeping

[Mr Tidy]

My 2nd E86 got MOT advisories 2 years running for the rear brake pipes being corroded, but the corrosion was at the end of the plastic cover in front of the rear passenger side wheel where road dirt builds up and holds water so hopefully it isn't a brake pipe. I got them replaced in Kunifer.

Hopefully you'll get a better idea of what it is with the subframe out.

[InterlagosMC]

Yeah I’d have thought above the tank would be better condition than exposed ends which on my car look clean and free of corrosion. I’ll just add it to the long list of jobs to be done

[Rockhopper]

The pipe failing above the tank is a very common thing. I had mine done a couple of years ago.

[InterlagosMC]

Quick update I’ve been keeping an eye on fuel and brake fluid levels all week as car rarely gets used and both are unchanged since last weekend which is really bugging me

[Rockhopper]

Mine didn't noticeably drop either but it was still leaking. It only takes a tiny amount.