illustration of why the 2000+ fuel door area rusts

[harofreak00]

How would one get the undercoating spray into that area?

We are talking about the area that you see everytime you open your fuel door. That is where the water is getting in. You can see the seem when you have the door open. If someone to put a small bead of sealant, it might work.

How are you going to get the fuel neck housing off of the quarterpanel? (Is that the part you are after as a "patch?") Can you break that black weld seal stuff with a chisel?

I'm not exactly sure what you are asking, as I already have this panel off the car. This panel was a test cut for *B2*, because I am going to sell him a rust-free patch panel. I was able to pull the panels apart with my hands, took a lot of muscle, but it finally popped.

[golfyeti]

I have the same problem in mine. Sucks big time :( its not bad , YET, just a little bubble, but I know whats coming ..

FWI: mine spread from just one little bubble 18 months ago to now some 25+ inter-connected bubbles reaching all the way down to under the fender rim. It's a really bad cancer that may be best addressed sooner than later...unless you're replacing the whole quarter that is.

[2000Silverbullet]

Good advice to silicone seal the seam from inside the fuel door.
I notice mine has a small hole on the bottom to drain water accumulation. I sealed that years ago because I didn't like the dirt that would come up from the wheel well into that area.
Water and dirt must wick into the seam and catalyse the cancer.
I've seen pictures of Bonne's with fist sized holes in the quarter panel under the fuel door.

[2000Silverbullet]

Ahhh Haaaa........I see where the problem is now! If you feel inside the pocket with the fuel door open you will feel a pocket on the hinge side against the outside that can fill with water and there's no way it's gonna drain out.

Fill that with silicone and it should stay dry and corrosion free. Stupid design!

[SLEking]

you guys should see m poor panel. its about 9 inches wide and moved up and around the fuel door and down to the bumper. i can fit a fist and a half in my hole. my dad brought some metal home and we are going to section the rust out and weld in the metal. ill let you know how it turns out. other than that my car is virtually rust free considering the previous owner had it double undercoated from the dealer

[skregal]

I think it is more of a design issue than a materials issue.

If you open the fuel door and put your finger down behind the hinge,
low toward the bottom, you find a ditch that can hold water.
No matter what material it is made of, if it has standing water
with no way to drain, it will rust eventually.

Maybe I will fill up that ditch with some black silicone if I can
find a way to get it in there.

Edit: Paul's reply posted before mine, so this is redundant

[Ponch 04]

What doesn't help is that GM place a 1/8" drain hole located just beneath the filler neck that is HIGHER than the rest of the gas filler pocket. This hole drains on top of the tire so when you are driving on wet or salted roads the tire flings crap up inside the gas filler pocket which then drains towards the seam between the fender and the gas filler pocket.

I have sealed the hole using some all weather silicone and it doesn't seem to take on as much water.

This time of year I blow the mentioned seam out with compressed air to get the debris out, wash it with soap and water, blow it out again to dry, and spray a crap load of penetrant oil down there and on the inside of the fender well and the foam seal via the trunk.

[harofreak00]

How did you get that picture?

[Ponch 04]

Pulled back the trunk liner on the drivers side, pointed the camera at the filler neck area and took the picture. Granted it took me about 15 tries to get a picture that was aimed at the right spot and in focus .

I originally posted the picture in this dicussion about +00 rust issues back in February:

viewtopic.php?f=8&t=16455&p=174422#p174422

I talked to a body shop that specialized in working on +00 bonnevilles and fixing the rust in this area. I asked them how could somebody prevent it from happening and they told me to not let gas spilt gas seap into the seam of the fender. That was their only advice.

[spidey3479]

Thanks for the pics and info. Mine is bubbled pretty bad. One day I'll get around to making the repair myself, can't afford that kind of repair rt now.

[2000Silverbullet]

What doesn't help is that GM place a 1/8" drain hole located just beneath the filler neck that is HIGHER than the rest of the gas filler pocket. This hole drains on top of the tire so when you are driving on wet or salted roads the tire flings crap up inside the gas filler pocket which then drains towards the seam between the fender and the gas filler pocket.

I have sealed the hole using some all weather silicone and it doesn't seem to take on as much water.

Ya I did the same the first year after I bought it new. Noticed more dirt/water came up from the hole than was draining out.

Maybe we should just silicone the whole door shut.......that would solve the fuel mileage issue too. LOL

Suppose I shouldn't worry though since I never drive it in the rain or winter.

[CMNTMXR57]

$525

yea.. I like your guy better already

The guy he got the qoute from is the body shop I've used for years. They did this to my GTP, which they completely cut out that section, welded, ground, and prepped it for paint, then painted.

They've done work on my Camaro (which was show quality), Tahoe, 2500HD, Aurora, and most recently fixed my GTO bringing it back to show quality and additionally doing the 3M 3,000 grit wet sanding process to the clear coat to remove orange peel.

So they do great work. He can be a little slow, but I'd rather he be slow and get it right than rush through stuff.

[2000Silverbullet]

OK as anal as I am I just had to seal up the fuel door recessed area with Grey silicone sealer.
It's still possible for the crevice to wick up water from the inside but that's not as bad as dirty salty water in standing pools.

Thanks for the advanced warning of a potential future consequence.
Corrective action has been taken to hopefully remediate the problem.

[Mark Fahey]

I know this is an older post but Friday, I told a friend of mine who has a 2003 Aurora to be on the lookout for this problem. Unfortunately, yesterday, I saw 3 bubbles in the paint around the fuel door so obviously the problem has started for me as well. I had just finished clay barring and Zainoing the car and thinking that despite all of the problems that I've had with this car since it was new, the body has held up very well. I clearly jinxed myself since it was only a day later that I saw the problem.

[deano55]

I had been looking at Buick Lesabre's with low milage and saw one with this same problem. I bought an 03 SSEI the other day and looked at that area and didn't see any problem there untill after it came back from a detail shop. I see to little bubbles about the size of pin heads (just great!!). I'm going to try to stall it for a while by drilling a hole behind it on the inside wheel well big enough to see whats going on and shoot some Rust Bullet in there then plug the hole with a rubber plug to take off every once in a while for inspection. I know it won't stop it but maybe it will slow it down. It's winter now so that means salt around here and I would'nt want to get to deep in it now anyways.

[Ryan from Ohio]

Is there any more of these patch panels available?

If so PM me a price.

[keir]

I have this also and it's good to now know how/why it exists.

[Ponch 04]

I just wanted to add one more area where water gets into this area. It comes in around the rubber doughnut sealing the filler neck. As these cars get older the rubber starts to to shrink, allowing water to come in from the fenderwell. I too have sealed the weap hole under the filler neck but it was still coming in around the filler neck. Just a little food for thought.

[Mad Myche]

The water gets in around the fuel door and sits in there.

As the proud owner of a rusted through door on my 99, I had wondered about the source when I first purchased. After one of our recent snows, I noticed how the aerodynamics distributed the salt water. Right in the path is the door recess. Question answered

I, too; had thought about shooting some undercoating to help prevent (once repaired)

[00Beast]

This is a different issue 00+. 92-99 the door itself rusts, 00+ the quarter panel below it rusts.