[mjgreen81]

I was replacing a number of fixings on the undershield of my F30 as it had been hanging down a bit loose (I think it was damaged before I bought it).

I noticed the undershield was cable tied to one of these pipes. I presume this was a 'fix' by someone working on it in the past (or perhaps the person who broke all the fixings).

I decided it was probably best to remove the cable tie as I presume it didn't come out of the factory like that and I figured that if the undershield ever got caught in something, it would rip out whatever that pipe is.

So my question is, what are those pipes? I had initially thought brake lines but why would there be four towards the rear/mid section of the car. They appear from underneath the undershield and go up next to what I presume is the fuel tank.

And did I do the correct thing removing the cable tie?

Thanks

[dmaxdmax]

Two might be brake lines and two fuel lines. I don't know how they're fastened, but you'll find it somewhere in realoem.com or newtis.info

Your theory sounds reasonable, though, especially if zip ties were protruding below the underskirt.

https://www.realoem.com/bmw/enUS/sho...diagId=34_2109

This is mine, but lots of clips. I'm sure there's a similar diagram under fuel supply.

https://www.realoem.com/bmw/enUS/sho...diagId=16_1041

[Gen13 F36]

Damn are those rust?

[mjgreen81]

Originally Posted by dmaxdmax

Two might be brake lines and two fuel lines. I don't know how they're fastened, but you'll find it somewhere in realoem.com or newtis.info

Your theory sounds reasonable, though, especially if zip ties were protruding below the underskirt.

https://www.realoem.com/bmw/enUS/sho...diagId=34_2109

This is mine, but lots of clips. I'm sure there's a similar diagram under fuel supply.

https://www.realoem.com/bmw/enUS/sho...diagId=16_1041

The zip tie was through the empty hole in the under shield you can see close to the hoses.

[mjgreen81]

Originally Posted by Gen13 F36

Damn are those rust?

My car is quite rusty underneath unfortunately, but the build up on the pipes is just dirt I think.

[weehe126]

I'm guessing the zip tie was just to keep the undersheild from rubbing/bouncing on the lines.

[bellguy]

I see this all the time on most cars of a certain age :-)
The two thin pipes are brake lines, the thick pipes are fuel lines.
Dirt on the fuel lines and surface rust on brake lines, wire brush the brake lines and grease them up, will stop/slow down the rust issue.
Because the brake lines run over the tank and therefore can't be seen, rust in that area does eventually become an issue, worth running fuel very low, dropping the tank and clean and grease the brake pipes up there also IF you have the means to work on it safely.

[dmaxdmax]

Originally Posted by weehe126

I'm guessing the zip tie was just to keep the undersheild from rubbing/bouncing on the lines.

Or he was maybe missing a clip for the underskirt and used the ziptie to hold it up with the fuel line...like a boss (moron).

[mjgreen81]

Originally Posted by dmaxdmax

Or he was maybe missing a clip for the underskirt and used the ziptie to hold it up with the fuel line...like a boss (moron).

My thoughts exactly!