I think this is somewhat related to the problem (at least in the area of the battery). I've seen it in several Bonnevilles and seems to be a lot more common than I first thought.

Here'* the GM Technical Bulletin.
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Floor Pan Corrosion Perforation in Battery Compartment (Install Repair Kit) #05-08-61-002 - (Jan 11, 2005)
Floor Pan Corrosion Perforation in Battery Compartment (Install Repair Kit)
2000-2005 Buick LeSabre

2000-2005 Cadillac DeVille

2000-2003 Oldsmobile Aurora

2000-2005 Pontiac Bonneville

Condition
Some customers may comment on corrosion (rust) in the floor pan in the area where the battery is located.

Cause
This condition may be caused by a weeping of acid from the battery or from a battery vent tube that has become dislodged.

Correction
Repair the damaged area using the parts and information contained in the floor pan repair panel kit.. Also, clean any area of the floor pan where acid may have been present with a solution of baking soda and water. Rinse and dry the area thoroughly.

Parts Information
The floor pan repair panel kit contains a replacement section of the floor pan, a battery hold down and instructions. The adhesive needs to be ordered at the time of the repair.

Part Number
Description

88948594
Panel Kit-Floor Pan Repair

12378567 (U.*.)

88901675 (Canada)
GM Metal Bonding Adhesive


Parts are currently available from GMSPO.

Warranty Information
For vehicles repaired under warranty, use:

Labor Operation
Description
Labor Time

S5230
Replace Floor Pan
2.6 hrs

Add:
Refinish/Clearcoat
0.7 hr

Add:
Material Codes
GM

Add:
Paint Mix Time
0.3 hr




GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION


© Copyright General Motors Corporation. All Rights Reserved.


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Document ID# 1581654
2004 Pontiac Bonneville

my battery area is fine, i didnt even POR15 it... my floor pan damage is strictly from water leaks

That'* good news. I had corrosion under the battery in my '02, and I can see it starting in my '04 as well. Also noted in some others. Just thought it may be of some relevance given the number of cases I've seen.

Andrew, thanks for bringing this back up. I was just going to tackle some rust tomorrow. I just ordered a quart of the POR-15.

For the painted surfaces did you use anything else before you applied the POR-15, ie cleaner or other POR-15 product? Or did you just sand to rough up the surface? For the most part I will be using it on everything on the undercarriage, suspension, etc. and beneath the back seat.

I'm wondering if I should spend another $30 for their 'Marine Clean' degreaser and "Metal-Ready" adhesion promoter. :?

Ok, for POR 15, if you have flaky rust, get it off. Clean away any grime, oil, dirt, etc... If it is surface rust left, thats even better than bare metal, or rust free metal. POR15 sticks to surface rusted metal better than bare metal. Apply, and let dry.

If you just have bare metal and your wanting to POR15, applying the metal etching(spelling?) that they offer.

Thanks slick. Most of what I have is rusted metal. Nothing clean or bare, so I just plan on getting all the loose rust off. I know some spots are oily, and I thought I'd use brake clean to clean it, then sand, then paint. I just don't want to spend too much on the other products.

you could try the magical solution that haro mentions earlier in the thread

If we knew what it was....

What is this magical solution Andrew...Peter? :?:

You don't really even need to sand it. Remove anything flaky, degrease it(brake cleaner is fine), spray it off with a hose to remove any oils or any other solutions, let dry, then go to down.

Wear long shirt and gloves that you don't mind ruining. I had a POR15 stain on my arm and wrist for 2 months before it finally wore away. In fact, wear goggles too.

Ok, so brake clean is fine...cool. I figured brake clean (some brands) left oily residue that POR-15 wouldn't like, so I'd sand a little more afterwards. I'm sure it will be fine.

Andrew, how were the fumes from all that paint?