Welding/Repairing Rust 01 Sierra

[ryans69chevy]

I got the typical bed rust on my 01 GMC Sierra. Both wheel arches are rusting away. I thought it was just surface, so tonight I took a screwdriver to start scraping the paint flakes and rust scales so I could sand it clean and spray primer. Soon i was scraping holes through. Realized it was more than I thought.

A few questions for you guys -

I found a pair of repair panels for $105 to do both sides from am-autoparts. Not sure if they are any good or not. Just tried to find the cheapest price. Does anybody know of any good panels that fit nicely without any big modifications?

I'm planning on doing all the work while the bed is still on the pickup. I'm looking for safety points on what I can do to be safe since I'll be welding in close proximity to the fuel tank. What things should I do to keep myself safe during this project? I'm use to welding on panels that are off a vehicle.

My plan for this pickup is to repair the panels and put it up for sale. So I don't want to put a lot of money into it.

Thanks for the suggestions.

[ryans69chevy]

Here is the rust. The other side is about the same, maybe a bit worse.

[72HuggerK20]

We never do those replacement panels anymore. With the time you have into them, you're better off doing the whole box side. Then you know what you've got. But since you're looking to sell it, and if you don't care about your time, go right ahead. I would highly suggest pulling the box off the pickup. It only takes an hour to take out the bolts, undo the wiring, take the filler neck loose, and take the tailgate. Then grab a few buddies to help lift it off. If you still don't, tape up the filler neck very well. Unhook the ground on the battery. Make sure you undercoat the **** out of the inside of everything when you get the old piece cut out. Weld through primer anywhere you will be welding. Trim up your patch to the general shape you want (you almost never need the whole thing, better to keep the repair small. But still cut out ALL of the rust). Then make the hole fit the patch, not the patch fit the hole. It'll save you a lot of time. Make the patch so that it'll lap behind the original panel. It'll be easier to weld, and reduce warpage. The height difference will be made up with filler. As far as safety, make sure you have safety glasses, a good welding helmet, welding gloves, and a good dust mask when sanding filler.

[ryans69chevy]

Thanks hugger for the response.

Yea I don't want to put a ton of money into it, so I'd rather just get the repair panels instead. I have more time than money. I understand the process of repairing the patch. I guess what I'm not sure about is the safety part of welding so close to the fuel tank. I have all the safety equipment for welding. I just am not familiar with welding close to a fuel tank. I just don't want a spark from welding to fly up and the gas vapor ignites.

I would like to take the bed off. I'm just not sure if I'll have the room to do all the work in the garage. So I'm looking for pointers for if I left the bed on the pickup. You mentioned taping the filler neck and unhooking the battery. Whats the reason behind that? Is there anything else I should do so I don't start a fire with the sparks of the welds?

Thanks

[72HuggerK20]

The reason for unhooking the ground on the battery is to break the circuit. Otherwise, a MIG welder typically running at around 19-22 volts when welding sheet metal will probably fry your ECM. Another thing that works is a service minder, but those are expensive and don't do any more than simply unhooking the battery. As far as spark protection, You can get a roll of 3M "spark paper", which is actually pretty great stuff, but it ain't cheap. Or a bunch of leathery welding blankets wrapped around sensitive parts is great too. I was just suggesting tape so that sparks have less of a chance to melt through the filler neck. You make a good point about the vapor possibly igniting. I still would highly highly recommend taking the bed off in the driveway, and then carrying it into the garage where you're working and set it on a couple sawhorses or something. They aren't heavy at all. Maybe 300 pounds at most. Once you have it off, you'll be glad you do.

[ryans69chevy]

Shoot maybe that's what I should do then. I guess I never realized they were that light.

[72HuggerK20]

A guy on each corner will have no problem lifting it off. An extra guy to guide the filler neck when putting it back on would be nice.

[ryans69chevy]

Right on! Now I have to come up with 4 friends!

[Indian113]

I'm going to take the box off my C10 and my S10 with a Engine Lift. It's easy and you can control it plus it doesn't drink as much beer as my Buddies!

[sevt_chevelle]

Hmm

Are you gonna gain back the money you put in that truck? I can tell you the inner wheel lip is also rusted, they rust from the inside out. Also willing to guess that the rockers are toast as well.

I have welded on countless parts in a collision setting, and never worried about the gas tank. Wrap the filler opening several times with masking tape and be done with it.

If you remove the box I would do yourself a favor and remove the rear bumper.

[ryans69chevy]

Yea, I hope I can. I guess then I feel like it will be an easy sale since the rest of the pickup is in nice shape. I figure I'll have to put in about $500 before I can sell it. If I tried to sell it right now I feel it would be tough to get the price I want since the box is such an eye sore. The rockers are actually pretty decent. It's basically just the wheel well that's shot. And yes, just like you said this one rusted from the inside out.

I guess maybe I was worrying too much about blowing something up. It's probably my inexperience to that.

[MARTINSR]

Just to cover a few things here. Unless you are welding within 12 inches of a computer module or the like you aren't going to hurt it. Not unless you were to put the neg clamp from your welder on the other side of the module and you have the power from the welder going THROUGH it, which of course you literally can't even do on this particular repair.

But honestly, that stuff was way over thought when cars started coming out with all that electrical computer stuff. Even batteries in a Hybrid we use to pull them out of the car that were mounted under the seat when we did something like a rear body panel. But that is history, all manufacturers have basic guidelines like do not weld within 12" of the component, it's that simple.

On the gas, if you cover the filler at that gas cap with a wet rag you are pretty much good to go. But that is rarely done, those caps on these late model cars are sealed off, unless you had a spark fall on top of the rubber hose and burnt through nothing can happen.

Cars are welded near the gas tank and fillers like that every day in 50k shops across America.

Being overly safe isn't a bad thing, I am not knocking anyone for being overly safe. But just to set the record straight on the subject.

Brian

[ryans69chevy]

Okay perfect that is good news. Yea, I'm just use to welding individual panels on a stand not on a running vehicle.
So is it necessary to unhook the battery? It was mentioned earlier. Is that just so nothing backfeeds and destroys electrical?

[MARTINSR]

Nope, we weld on cars every single day and don't.


Brian

[ryans69chevy]

Okay thanks for all the responses. I definitely learned something new!

[MARTINSR]

And might I also add that we have inspections by a company called "Verifacts", and did so yesterday. They walk through the shop unannounced inspecting how things are done, inspecting weld quality, protection of the car, are we following manufacturers guidelines?

We get the manufacturers guidelines on how to replace any welded on part from a company called "Alldata" print it out and put it in every single car that is getting a weld on part. And other parts too, but we really make sure on weld on parts. But all suspension parts, the tech gets a manufacturer guideline including all torque specs.

Probably 90% of the cars we work on are less than 5 years old.

We have all cars made after 2012 pre and post scanned for all electrical systems. We take this stuff very seriously, and yes we have had an incident where a computer in a car got cooked but it was because the guy made a MORONIC mistake.

I remember when we were taking the batteries out of all the hybreds we did if we were welding on them. I went to a Toyota training and they about laughed at that. They said unless you are welding so close that you would damage the battery with heat that is pretty much unneeded. The basic rule is 12 inches. That goes for air bags, computers, batteries, everything.

Brian

[ryans69chevy]

That's some good information! I never knew that. That's cool that you get all that experience. I didn't realize you worked in a body shop. I've read through a bunch of your FAQS. They are very helpful and informative! I appreciate your time and knowledge that you contributed to this forum.

[MARTINSR]

But I can't make it clear enough, being overly cautious is a good thing. And reading this thing again it did hit me that we leave that Prius battery but it's disconnected! So listen to the others here and be very careful, unhooking the battery isn't going to hurt a thing, it's better to be cautious.

Brian

[hugger6933]

I unhook the cable but that is just being that has carried over from when trucks first had ECM's back in the 1980's. I am still in that habit. most of the time the cable is unhooked cause the truck is torn apart anyway. As far as the tank goes I've welded in rear sections [frame] a bunch of times without removing the tank. You are gonna need inner wheel "humps" as they are gonna be rusted too. Check te lower cab corners and rockers you may need those too normally if the bed is rusted the cab will be too. Jim

[ryans69chevy]

I found that inner wheel arch for $60 a side. Is that actually needed? Would it work to just cut it out and weld in only the outside wheel arch? I felt behind the wheel arch and could feel that panel or bits of it crumbling in my hand so that panel is toast as well. Rather not spend another $120 on that. But if it's something that will Ben pretty noticeable I'll have to do it. Haven't been able to start cutting the rust out yet.