Fuel Tank Breather

[dragonz 16]

So it's almost a year since I got my 335i, & for the most part I would only partially fill the fuel tank, because why cart more gas than needed.

However on the few occasions that I did fill the tank, I would notice a very strong raw petrol smell until the fuel level got down to 1/2 tank or below.

Read a couple of things that indicated an issue with the carbon canister in the venting, priced replacement & thought f**k that, & carried on regardless.

Then one day after filling the tank, I parked the car across a slope, with the drivers side down hill.

As I got out of the car I saw petrol dripping from just in front of the right rear wheel. After getting over the shock, I turned the car round so it was across the slope the other way & once I was happy that there was no more fuel running out, went about my business for the day.

Started digging & found that there have been a number of the E90 series cars with this issue, & it appears that the breather hose that runs from the top of the tank to the neck of the fuel filler could be damaged due to excessive movement of the tank.

So, last week was a quiet week for work, & I finally got the chance to get under the car & repair the issue. I had bought a replacement vent hose, & expected that it would be a fairly simple, if somewhat laborious, task, to lower the fuel tank sufficiently to get to the breather hose & replace it.

More fool me!

When I got to that point, I discovered that the breather spigot that the vent hose clips onto had broken out of the fuel tank completely!

This then necessitated the complete removal of the fuel tank.

For those who have not had the pleasure, this requires removing the driveshaft & the handbrake cables (I had already removed the exhaust system) & this is where the fun starts.

To remove the driveshaft requires a 50mm open-end spanner & lots of brute force to undo the coupling point with the diff.

To remove the handbrake cables, requires gutting out & removing the entire centre console! 

Once I had the tank out & could see the damage, I called BMW for a price. $1530+GST, & special order from Germany! Further explicatives followed for some strange reason!

Fortunately, many years ago I had sold some fellow car enthusiasts a tig welder, & they happen to run a company Plastics Constructions, in Avondale. I gave Richard a call, "can you weld a plastic fuel tank?". He checked the material, & "yes no problem" was his reply. He made a beaut job of it, & it's now probably stronger than the original. 

So, if you notice strong fuel smells when you fill the tank, this may be something to watch for. Another check I would suggest, is to lift the rear of the car when the tank is empty, & make sure that the tank is tightly held by the securing straps. I was able to move my tank up & down by more than 10mm when I got underneath, & I have fixed this by putting thicker heavier foam blocks between the tank & the bodywork when I reinstalled the tank.

I still need to finish reassembly of the interior & final bolt-up of the exhaust, but at least my car won't leak petrol any more.

I will post some photos of the process & what to look for when I get the job completed

 

  

[allan 295]

holy grap k boom man the gods were looking after you. Glad you got it fixed and who you know not what you know came to the front yet again with $$$$$ saved.

Would this be a design fault, securing brackets coming loose, not enough packing between tank and body etc. BMW any use for info?. 

[B.M.W Ltd 950]

I've had to deal with fuel tank security issues many times on Euro cars. More on BMW's though

[Gaz 1062]

If you have a Japanese imported f20 then I suggest contacting your local dealer to check for any outstanding recalls as some of them required a replacement 

[martyyyn 102]

I've just gone through the exact same thing last week in the e90 320d. Our son got home five minutes after filling the tank and it was pouring out from under the drivers rear quarter.

I don't have the time, skills or tools to sort this one so this is where the fun started.

Long story short, I had to try a local mechanic rather than my usual place. They had it for 3 days, charged me for 7 hours (it's a 4 hour job at most) and left me with a broken handbrake.

There was actually nothing wrong with the handbrake they just hadn't taken it out of "service mode" and readjusted the cables at the hubs (a ten minute job) but they were convinced the adjusters were seized and it needed more parts and another two hours minimum to fix.

Muppets.

There are plenty of comments about this in E90 forums around the world. All coming from the vent hose feeding through the rear wheel arch and there being nothing between the hose and the hole so the hose rubs against it and ends up being torn, therefore leaking fuel. Several people in the UK have had success with BMW paying 50% of the repair but good luck with getting that in NZ with a 10+ year old car and multiple owners.

Both diesel and petrol share the same tank and hoses but it's mostly diesel drivers who notice it because the dripping petrol tends to evaporate first, but I'd suggest all E90 owners get this checked out.

[dragonz 16]

A couple of pics of the damaged tank

[dragonz 16]

Some pics of the repaired tank & the new foam blocks I put in place.

As I had purchased a new vent hose I put it on, even though the original wasn't leaking. It did have a slight rub mark, but could still be used.

Sing out if anyone needs one ?

[dragonz 16]

The car up on my hoists

I have a set of hydraulic ramps that are supporting the front of the car, & a pair of air/oil single post hoists that I used to lift the rear