Found some battery acid damage...how bad-spot repair?

[efhughes3]

Yesterday I was "nut & bolting" my car for a DE next weekend, and saw a couple of ugly "sores" up front underneath. The one toward the center was perforated, and I dug at it with my finger to open it up a bit. I'm sure it's damage from the old wet cell that I replaced a couple of years ago. I'd had a little evidence up inside the boot that I treated with rust inhibitor and then rattle canned.

What's the prognosis? I don't see this damage up inside the trunk, this was probably the low spot where some acid did its work.

Is there any chance of a spot repair here? Obviously, until I were to start cutting the area out, I don't know the true extent, but I dont want to do a full pan if not needed. The front control arm mounts look OK, but there is another "sore" several inches away from that, but it didn't disintegrate when poked.

[robmog]

patchable. see darryl's work here.
http://www.darrylsgarage.com/912/912FEB06.htm
it's always worse than it looks but maybe pan replacement is avoidable.
cut it open and look around with a light and mirror
pan jobs are one big PITA

[efhughes3]

Bob, that is very helpful-thanks.

[Bobboloo]

I would section off a large portion of the gas tank support, over the affected area of the pan, so you can see the extent of the damage to the pan. The view from the underside only shows the area where it rusted through. If you remove a section of the gas tank support it allows you to remove any surface rust on the other side that you don't see. Then after the welding repair of the pan you can etch and paint/POR-15 this gully in the pan before you close it from the top with the gas tank support.

The idea here is to stop the rust process. What really caused the rust was exposure caused by battery acid removing the paint. If you don't get this area painted on the inside it will rust all over again after being repaired. I've seen many replaced pans needing a second replacement because they weren't painted properly after replacement. You see them on Ebay all the time.

[efhughes3]

Bobby, I was thinking along those lines too. Thanks.

[efhughes3]

Today, I dug deeper. The undercoating was somewhat comprimised in the vicinity, and when I got off that which would come off pretty easily, I saw a 2" X 4" area of damage. So, I cut it out to where I had pretty good metal left. I stuck a mirror up to see what it looks like inside, and there was corrosion evident, but seemingly in the center of the low part of the front pan. The area surrounding the A arm connection seems good. I don't know if that will make a difference in the breadth of the ultimate repair, or not.

So, armed with the knowledge gained, I sprayed Krylon Rust Reformer around inside-hoping to arrest the disease or at least retard it. I then cut a patch and formed it a bit to match the old. After cutting back the undercoating, I tacked it in place. The fun part here is getting to use some of my metal tools and my "el cheapo" mig welder. Although, it wasn't fun working around the gas tank. I put some wood up around the work area to protect everything and took it slow.

After I got the patch in, I knocked the welds down a bit, primered and then sprayed some Wurth undercoating on. Pics of all of the steps below.

The bottom line: I just ordered a new front pan from Restoration Design. I don't know if it will be better to replace the whole pan, or to cut out the center channel between the front A arm mounts and use the front pan as a donor for that portion. I'm going to leave that to a professional. There are a couple of good P-car body shops in these parts (gotta love SoCal), so she'll go in for repair by a pro. She's good for the time being. Keep your eyes open when poking about your cars!

[robmog]

you did an excellent job.
why'd you buy a new pan?
that should last years.

[efhughes3]

Just paranoid with there being more rust at work in there, and getting to the suspension pick-up points, I guess.

[Bobboloo]

Good job! Fun stuff!

You should probably drill a drain hole since the one that was there is gone now. Also if there's an access hole from the top then pour or spray some POR-15 in there from the top to paint the back side of your repair.

No need to replace good metal so just sell that RD suspension pan.

You should also clear and repaint the other two drain holes.

[efhughes3]

I'm going to run the fuel tank down pretty low and then jack it up for access and full inspection from the top.

[efhughes3]

You know what? It is pretty fun. If I had a garage queen sitting out there, I'd probably not be so quick to chop and burn. But, it is good experience-who knows maybe someday I'll take on a resto project?

[Zeke]

Nice job!

Resto project? Can you say slippery slope?

[efhughes3]

Originally Posted by milt

Nice job!

Resto project? Can you say slippery slope?

I must've had a few beers in me when I typed that! Too short on time, and certainly money nowadays to even think about such a project now.