Crushed Gas Tank. Removing old need help

[bolomiester]

I'm picking up another tank today, but I have a question for our experts. We have to remove the passenger side inner fender to get to the fuel vapor diagnostic pump and vent line. All the fasteners are out but there is an electrical box preventing us from removing the fender liner. You can see it below, circled in red. It looks like it's riveted in place as we see no screws and we've pried on it thinking it might snap in place but it doesn't want to move.

Riveting seems wrong since there are serviceable parts in there but does anyone know how it comes off?

I'll have photo of the tank differences to post later today.

[Edwin NL]

There are 2 fasteners in the middle (plastic) take a screw driver and pry them out, or press the centre and push the pin out that is in the middle and it come right off.

Good luck

[bolomiester]

Thanks Edwin.

[01sport]

When I had my rear bumper replaced the body shop used plastic pop rivets to install the wheel liner. I told then that they were not original equipment. The guy said 'Oh yes they are. These are BMW rivets!"
"Nice try" I told them. Then I made them cut out the rivets and order the speed nuts and galvanized screws that were original equipment. I can be such a &%$#@ sometimes.

[stanley]

How did the tank get damaged? Was it hit or get caved in. They had a problem with spiders in vent tube, yes spiders. There is a replacment vent tube for this.

[paprmkr]

my tank has this popping sound at startup after sitting for sometime. i guess i may be doing this work on mine soon

[meteck]

Check the vent tube.

[bolomiester]

How did the tank get damaged? Was it hit or get caved in. They had a problem with spiders in vent tube, yes spiders. There is a replacment vent tube for this.

Yes, it was spiders. Other than an occasional thump in the back when sitting in traffic the car had no symptoms. The first clue was when it ran out of gas with the gauge showing a quarter tank. Even then I thought I had a fuel level sending unit problem. A couple of days later it went into the shop for new front brakes and that was when we discovered the tank was crushed. There is a service bulletin posted on e38.org, http://www.e38.org/SI.New.Evaporativ...Purge.Line.pdf, that will give you the details. Unfortunately I did not know this situation existed until I posted on this forum. I bought the updated, spider proof, vent pipe, part #16131184554 from the dealer for $15.58.

Had I suspected the vent pipe problem before it was totally blocked I could have saved having to track down and buy a used tank, new ones are almost $1,000 or even more if you have SLS, and about 6-7 hours labor. Fortunately one of our members, bmwlefeber, had a beautiful one on hand at a good price.

[stanley]

As I work at a dealership, 41 years, one of my techs was the one that found the spiders and we made a report to BMWNA about it.

[coleshooter]

The only safe fix after finding the spider colony.

[bolomiester]

I bought the updated, spider proof, vent pipe, part #16131184554 from the dealer for $15.58.

Looks like I may have the wrong vent pipe. Brian, from the shop, called this morning to say the one the local dealer sold me, #16131184554, is for the 1994-1995 model and doesn't fit. I'm having a hard figuring out what the correct vent pipe for my car would be. It's a 3/98 740iL model. I've been looking online and it could possibly be #16131182246, but it looks to me like that part is listed as a fuel feed pipe.

Can anyone tell me the correct part number for the "spider proof" vent pipe for my 3/98 740iL? Thanks.

[jeison33]

Were is the vent tube located?

[bolomiester]

Were is the vent tube located?

It's behind the passenger's side inner wheel liner. It connects to the center of the carbon canister, goes over the top on the expansion tank and disappears into the front of the wheel opening. When replacing it. The updated vent pipe is shorter and just goes over the top of the expansion tank and ends at its forward end.

[bolomiester]

The job is finally done. I wasn't able to sort out the correct updated vent pipe situation, but my mechanic came up with a solution. He cut the old pipe just in front of the expansion tank and discovered that the old pipe was small enough to slide tightly into the new one. So he cut the new one off pretty close to end. He then heated the new pipe up just enough to make it flexible and slid the old one into it. When they cooled there is no way for them to come apart. Just to be sure there were no spider webs in the part he reused he made a cleaning kit out of an old speedometer cable and a rifle cleaning patch holder. He ran it through the old pipe to insure there wasn't a trace of web in it. There wasn't.

In addition to that and replacing the collapsed tank, he also installed a new fuel vapor detection pump, the part that had thrown a code earlier.

Final bill:
Labor - $445
Used 2001 gas tank - $100
Updated vent pipe - $16
Fuel vapor detection pump - $124
Gas cap - $9
exhaust gaskets and brackets - $10
Fuel pump & sending unit gaskets - $9
Misc. bolts washers & nuts (broken during dis-assembly) - $20
Misc. clamps & hoses - $20
Total - $753

Not bad as 7 series repairs go but a lot when you consider it was caused by tiny little spiders.

[jjc034]

So I believe I fixed my issue. I suffered from a heavy "glue glue glug" sound in gas tank, which I knew was due to a venting issue. First I replaced gas cap, no luck. Second I replaced vent piece in gas tank by the pickup, no luck again. Thirdly, I noticed the leak detection pump wires were chaffed so I repaired those hoping it would enable a vent valve to open, nothing. Finally, I took a look at the vent tube running from charcoal canister to body of car. I realized that even though mine was an '01 it was missing the updated part! I decided to cut the tube and confirm blockage. Sure enough I turned red trying to blow through the chassis side pipe, while the charcoal canister side was fine. I placed the tube back and we'll see how it works! Shouldn't get any codes for major leaks since that tube always dumped to atmosphere.

This was a painful process! Luckily my gas tank doesn't leak so I'm going to keep using it.

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[nmlss2006]

Waaaaaaait a minute. The blue line is factory?!?

[jjc034]

Waaaaaaait a minute. The blue line is factory?!?

Don't know, but looks it to me

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[nmlss2006]

I ask because I have the exact same blue line in my 750 and I thought it was a COLORFUL CHANGE by the PO...

[jjc034]

I ask because I have the exact same blue line in my 750 and I thought it was a COLORFUL CHANGE by the PO...

No clue to be honest, but it fixed my problem

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[ddrewyor]

So I had the same "boinging" noise from fuel leaving the tank, but no air entering on my 740i. Car sat for three years and did not have the issue when parked so I guess the spiders got to it!
I cut the vent line (completely blocked) and put a small engine fuel filter on to keep dust and stuff out. Seems to work well. Blue line is factory. I'm the second owner and I know the original owner and he never did anything to this area of the vehicle. By the way, I snapped the fourth line into the holder right after I took the picture!
My thanks to JJC034 for working with me on this and the whistling noise that is also there.
IMG_0720.JPG

[ddrewyor]

The hose that I cut was not the correct vent line. I think I fixed it this time!!!
Here is what I did after removing inner fender liner:

• Drop the Expansion tank at top of wheel well to give you room to work when you drop the canister.
• Dropped Charcoal Canister. Lift up and pull top forward then out. Otherwise you break tab off back. Yep - you guessed it, mine broke!
• Remove hoses from top - squeeze sides and ring releases, then pull out. Remove rubber hose from the pump.
• Removed Dust Filter (cylinder canister on side of charcoal canister) This is where supplemental air goes in.
• Checked hose and filter for clogs. Good Airflow was present
• Blew into Leakage Detection Pump (LDP) where Dust Filter hose attached. Bad airflow
• Removed LDP three screws on bottom and it pulls out.
• Blew into LDP. Good Airflow
• Blew into Charcoal canister and barely any airflow. Ah Ha
• Drilled 1/2" hole near bottom. Put your hole a bit higher than mine as there is a paper filter cartridge at bottom.
• Shook out charcoal. Black at first, then white clumped together. I used a piece of 12 ga wire to "scoop" it out. Tapped on side of canister with rubber mallet periodically. This only emptied out the small side of the canister
• Covered hole with finger and blew into inlet. Great airflow (could possibly be better because the large side may be compromised also, but I have nothing to compare it to). Felt airflow was adequate to supply enough make-up air.
• Took JB Plastic Bonder and capped with plastic plug like in picture.
• Covered in light coating of Black RTV.
• Reinstall components
• Fixed cut hose from earlier adventure

Ok - test ride for ~50 miles with 5 engine shut down cycles in that drive. No codes, CEL, or faults. Also, no boing
I will update if anything shows up fault wise. I have an Autel and if there is any issue pending, it usually shows long before a CEL comes on. Good Luck

IMG_0726.jpgIMG_0727.jpgIMG_0728.jpg

[ddrewyor]

Update:
I have now driven the car for over 200 miles and everything seems good. I also noticed that my tank fills without having to regulate the fuel flow with the handle. It has been like that since I acquired the car. Thought it was just a bad design. Maybe it was my charcoal canister slowly failing.

[jjc034]

Update:
I have now driven the car for over 200 miles and everything seems good. I also noticed that my tank fills without having to regulate the fuel flow with the handle. It has been like that since I acquired the car. Thought it was just a bad design. Maybe it was my charcoal canister slowly failing.

Now it sounds like your BMW ownership experience is going to become uneventful lol. All the fun is taken out!

Serious note, fantastic job looking into this and diving further than I did/ analyzing shortcomings to my method. I plan on using your guide to fix my problem as well.

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