Pinhole Remedy After Welding Sheetmetal Patches?

[GeorgeH]

. Half of all new cars are put together with the stuff, it is made to adhere to bare metal.

Not correct. Oem's for the most part use weld/bonding techniques where the adhesives are spot welded through on steel panels and bonding and rivets or welding on aluminum. It impossible to duplicate in the aftermarket without some high end welding equipment such as a Pro-Spot machine. The adhesives used at the oem level are a long way from 3M panel bond and the like. There is not an oem out there that condones gluing there cars together as a repair procedure. Gluing a car together will get someone killed if it gets hit again.

 

[GeorgeH]

We aren't building a 100 story skyscraper here, and the welds don't have to be x-rayed. Panel bond will fill those holes, and it will do it very well. It's even sandable and paintable if need be.

No, but blanket statements like yours are what leads people to think it's ok to glue rocker panels and door posts in an such. Every part on a unibody is structural.

 

[rednesss]

Not correct. Oem's for the most part use weld/bonding techniques where the adhesives are spot welded through the on steel and bonding and rivets or welding on aluminum. It impossible to duplicate in the aftermarket without some high end welding equipment such as a Pro-Spot machine. The adhesives used at the oem level are a long way from 3M panel bond and the like. There is not an oem out there that condones gluing there cars together as a repair procedure. Gluing a car together will get someone killed if it gets hit again.

That's not true at all, who do you think makes the adhesive that OEM's use?? Answer, 3M, Lord Fusor, etc... The spot welds are just there to keep the parts from sliding around while the panel bond cures. You can cream an entire quarter skin on and rosette weld it where it needs to be with a cheap MIG. ASE procedures, as well as manufacturer recommendations for collision repair, call for structural panels to be adhered all the freakin time. Even aluminum ****. You're talking out your backside here.

 

[mopar head]

We`re talkin pin holes fellas, not rocket surgery.

 

[GeorgeH]

..

 

[GeorgeH]

We`re talkin pin holes fellas, not rocket surgery.

True, but it's only metal and not so difficult to go back and touch it up. A bad weld is a bad weld that can lead to cracks and other problems later.

 

[jos51700]

Exactly. All kinds of stuff is welded that has to be air tight, fuel tight, even pressurized at high pressure,. Fuel tanks, propane tanks, oil pipelines, etc, it's a long list. Pin holes are not inevitable.



That's exactly the point. It doesn't react with the metal. It literally will not mix. And if (and WHEN) it leaks, moisture gets behind the repair and it rusts out. The metal on these cars flexes, the resin will separate, and the repair will fail.

I'll agree that pinholes are not inevitable, but to be fair, most thin gage applications are pinch roller welded or some other methods.

And I would never advise using fiberglass to fill a pinhole.

If you're getting lots of pinholes, try adjusting your gas postflow to flow gas a little longer after the weld, and keep your torch on the weld until the gas shuts off.

 

[gdrill]

Well, filling holes with glass may not be the best solution........if you think you're going to outlive your car. However, regardless, I cover all my welding with glass. There may or may not be "pinholes", but the glass is my last great act of defiance against the inevitable future......loooong after I'm gone.

Oh, and yes, the factory used lead in a lot of applications. Well, guess what......it failed to.

 

[kursplat]

If you're getting lots of pinholes, try adjusting your gas postflow to flow gas a little longer after the weld, and keep your torch on the weld until the gas shuts off.

nice welder if you can do that.... buy some junk panels and practice until you can weld them without the pin holes. try different wire / wire sizes and feeds until you get it dialed in.
to be fair, any of these cars that isn't E-coated is going to have some rust some place, no matter how much blasting you do. you'll NEVER get it all out. so worrying about the inevitable rust bomb left behind by glassing over some pin holes, is to me, pretty mild on the scale of **** i potentially have available to me to worry about....but hey, that's just me

 

[Dartswinger70]

Bullshit, I don't know where you heard that from, but fiberglass is an insulator when there are two different metals touching each other, to prevent corrosion.

I have heard this also, the welds should be sealed with fiberglass,or similar product. Plastic filler isnt waterproof, fiberglass is. Or thats what I have read/heard.

 

[barbee6043]

An old man's take. There is a difference in quality of migs, some just allow a better weld than the cheapo stuff, just as there is a difference in wire, welder's ability, quality of metal, as in rusty floor metal!!!!!! Mig does not do well with any contamination on metal, as in any type of rust, oil, any contamination. The small .023 require gas, some gas is better than other, a pure or blend of gas, any air blowing away your gas? I sometimes make welds outside with .030 and no gas nad have good clean welds with what was a $600 welder bought 25 years ago. I am NO pro welder either!
Clean the metal real good before welding, flap disc, wire cup, on rusty floors I have sprayed Ospho ( phosphoric acid solution , used weld thru spray, etc) flumes are not good!),, After you have ground down your welds and if you see minute pinholes, I would retreat with the Ospho to help clean the welds, next day I wipe it clean with laquer thinner, wax and grease remover, and spray with a good epoxy primer, then use a GOOD body filler over that, NEVER any need for fiberglass really anywhere if you are doing adequate work IMHO>
Hardest place to get good welds is the floor pans, unless maybe it was blasted, and then you have nothing left!! LOL Make it solid and go on here, the carpet will cover it. Floors: I find excellent results spraying a good epoxy primer, topcoats floors with any type tractor enamel, I ever use Asphalt roof repair in the caulking tubes,as a sealer ( laugh if you like it works, and cheap unlike auto body sealer) ......Pretty work on the outside is where it is important.

 

[furyus2]

I've done a few panel replacements in my time. If I get pinholes, I go back over with the mig. Fiberglass expands at a different rate than metal. Eventually it seperates. Remember the hoodscoops people glassed on back in the 70s, and 80s. They always cracked. When done, I use seam sealer.