Finishing a Patch and Its Weld

[2002#3]

I have welded in place the usually-not-visible footwell-firewall patch shown in the pre-weld photo below.  The weld has been ground to be relatively flat and contains pinholes.  Of course, the external surfaces of the final work will be exposed to the elements and to exhaust heat.  The patch and surrounding area:  only raw metal; no rust; not tar-like sound deadner.  The pre-weld surface rust you see on the patch in the photo is no longer there.. 

 

Here are my finishing tools at hand:  Eastman Contour body filler and activator, SEM seam/body sealer, MAX epoxy primer, and MAX 1K Fillclean paint.  Seems to me the order of operation and order of application of these products will be important.  Therefore, the question:  

 

Q:  What might be your suggestion re: the next steps to close, seal, and finish the work - both outside (engine bay) and insider (footwell) the patch. 

 

Thanks.

 

 

 

[Dudeland]

We need to see the post weld photo. 

 

[2002#3]

Dang!  I knew someone would want to see the post-weld photo.  The weld is solid and has some pinholes...it's just not aesthetically pleasing.

 

Thing is, my bud is a good welder and wanted a trial exercise to tryout his nifty, all-new, virgin TIG welder for an initial run.  He had to lay on his back to do this and could never seem to get a good angle with the electrode.  He was exceedingly disappointed in his efforts and made me promise not post his work.  To anyone.  I lied.  He is a Porsche guy and I don't think he will see this post.  Please do not tell him.

 

PS:  Dudeland, thanks for prompting me to come clean.  I feel better.  

 

[bergie33]

Looks about as good as my front subframe reinforcement job that I did.

[tech71]

9 hours ago, 2002#3 said:

What might be your suggestion re: the next steps to close, seal, and finish the work - both outside (engine bay) and insider (footwell) the patch. 

Working from your available stuff, I would apply 2 medium coats of the Max epoxy primer to cleaned surfaces both sides followed by a layer of the Sem sealer. It’s a small enough area, use a spatula, like frosting a cake😉

 

 

 

 

 

[Dudeland]

9 hours ago, 2002#3 said:

Dang!  I knew someone would want to see the post-weld photo.  The weld is solid and has some pinholes...it's just not aesthetically pleasing.

 

Thing is, my bud is a good welder and wanted a trial exercise to tryout his nifty, all-new, virgin TIG welder for an initial run.  He had to lay on his back to do this and could never seem to get a good angle with the electrode.  He was exceedingly disappointed in his efforts and made me promise not post his work.  To anyone.  I lied.  He is a Porsche guy and I don't think he will see this post.  Please do not tell him.

 

PS:  Dudeland, thanks for prompting me to come clean.  I feel better.  

 

The first project I used my welder for was building a welding cart. Twenty-five years later, I still have it and am reminded of my humble beginnings. It looks like it will stick, and it isn't structural, so all is good. I suspect that it was a .35mm flux core, which is very, very hard to use. If your welder doesn't have a variable heat setting(i.e., a dial, not a selector switch), it is harder again. 

 

When I butt weld sheet metal I use.25 mild steel with 80% argon/ 20%co2 mix gas.  A little tappy tap, and it is just ok.   I just got a tig, and ohhhh boy, "goopy pool of aluminum snot" doesn't begin to describe what I did to my center console.  

 

I put some 3m seam sealer on my floor pan welding sins, and I feel that the flexibility will help keep the water out.  Zap that with some paint, and you are off to the races. 

 

I do like Steelit, a stainless steel polymer that you can weld through. It is super durable and flexible, and those I have recommended it to have had positive things to say about it. At $33 (ish) a can, you can use it sparingly, and coverage is very good. 

 

Amazon is expensive, but other retailers have better prices. 

 

P.S. Please feel free to critique my booger welds; they are especially tasty on the cross bars for my seats.  They aren't pretty but they are strong... just like me . lol 

 

 

 

 

 

 

[zinz]

Any of the seam sealers you already have will work just fine. Wipe the area with alcohol or other solvent for a clean surface and apply. 
 

@BarneyT and I found the POR15 seam sealer paste works very well. It’s fairly thick and you can smooth it out with a gloved finger.  It dries hard and sandable. 

 

Available thru lots of retailers. Jeff Bezos can deliver it to your door, even. 
 

Ed Z

Edited September 28 by zinz

[BimmerRover]

I’d put a light source on one side or the other and make sure you dont have anything bigger than a “pinhole” in your weld. Seam sealer isn’t meant to be body filler. Clean the patch and surrounding are with W&G remover, scuff it up with some 80grit, spray some self etch on it, seam seal it, then spray the underside with a decent undercoating. 

[Mike Self]

3 hours ago, zinz said:

POR15 seam sealer paste works very well. It’s fairly thick and you can smooth it out with a gloved finger.  It dries hard and sandable. 

+1 on this stuff.  You can patch a hole up to 1x1" or so with some POR15 and fiberglass window screen in non-structural areas--a hole that's hardly worth dragging the welder out for.  Clean back to clean metal, grind off any paint/remaining rust, and ding the edges down just a little.  Cut the patch  3/8" larger than the hole, butter the hole edge and press the screen into the wet POR paste.  Let it dry overnight, then fill in the screen (from both sides if possible) with more POR paste, and let it dry.  Check for pinholes and fix.  Once it's thoroughly cured, skim filler over it, or if under the car, just use schutz or even roofing cement as an undercoat.  I have these patches that have been holding for 5 + years on daily drivers...road salt and all.

 

mike

[Son of Marty]

3 hours ago, BimmerRover said:

I’d put a light source on one side or the other and make sure you dont have anything bigger than a “pinhole” in your weld.

Plus one on the bright light under the car turn off the shop lights and watch for stars around the seam.

[VWScott]

Definitely seam sealer. I finish up my repairs with Herculiner brush on bed liner. Abrasion resistant and easy to repair with just brushing it on. Does not get brittle either.

[Markster]

I went with Wurth.  

 

I mig welded up a sunken socket to reach the stock spare tire hold down rod.  It also needed to be low profile so the wooden deck sat flat on the spare.  
 

My body shop swore by Wurth.  I just use the disposable brushes that are used by plumbers to apply flux. (Back in the day!)

 

 

 

 

 

 

 

 

 

 

 

[SydneyTii]

Love those Kooglewerks rear battery holders! Christmas pressie me thinks😁

[Markster]

27 minutes ago, SydneyTii said:

Love those Kooglewerks rear battery holders! Christmas pressie me thinks😁

I would ask Santa to supply the top bar with one eye bolt that is reverse thread so when you rotate it it adjusts! 

[SydneyTii]

16 minutes ago, Markster said:

I would ask Santa to supply the top bar with one eye bolt that is reverse thread so when you rotate it it adjusts! 

Intrigued, what do you mean?