Tar-like undercoating on 63 Valiant...any way to remove it?

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B-i-n-g-o

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Started pulling the old fuel line, and, as I worked my way forward, realized the whole underside is coated in a dry tar-like material. This 1963 dealer rustproofing, a 70s JC Whitney thing, or what?

Any way to get it at least mostly off without blowing the car apart? I fear it'd turn into another unfinished project if I did that.

Thanks,
Steve
 
I've used several methods over the years, all with varying levels of success. I will often use a combination of different tools to get it all off.

An air chisel with the pressure turned WAY down works really well on flat spots. You just have to be careful to keep the tool at an angle so you get underneath the coating without beating the crap out of the panel. It should come off in strips if done correctly. You can also use an oscillating scraping tool.

Another way is to heat up a paint scraper to cherry red and scrape it off. I personally don't like the fumes when doing this unless you have a lot of air flow.

Last method is a stiff wire wheel. It gets everywhere. Super messy job. This is my least favorite way, but sometimes you need to do it in tight spots.
 
B-i-n-g-o said:
Started pulling the old fuel line, and, as I worked my way forward, realized the whole underside is coated in a dry tar-like material. This 1963 dealer rustproofing, a 70s JC Whitney thing, or what?

Any way to get it at least mostly off without blowing the car apart? I fear it'd turn into another unfinished project if I did that.

Thanks,
Steve
Click to expand...

Few options... mostly involving scraping... I had success with my 64 using a heat gun (carefully) and a multipurpose tool with flexible scraping attachment along with a putty knife and wire wheel. It was messy and took a lot of time.

I tried the oven cleaner and other liquid/ chemical approaches and at least for me they did not work at all... Others have had success.

Good luck

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Heat gun and putty knife as stated above works well. Don't forget long sleeves and gloves.
 
We did it with a propane torch and putty knives. Heating the undercoating and scraping it off.
Started out with a heat gun but found a propane torch was faster. My kid just getting started on it.
Going to be his car after all...
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It was a bit of work but effective. It went to media blasting once we had the undercoating off.

Next time I may try this Dry Ice method or just do it in when it's very cold out...
I've also seen this done with the car right side up and the dry ice on the inside to get it cold and chip it off in chunks.
 
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If it ain't broke don't fix it.

The tar is the factory undercoat.
It has done it's job for 50 to 60 years.

Fix areas that need fixing.


If you are hell bent on removing it...

I removed some from a fender with propane torch, watch the flame and the tar catching fire. It tends to self extinguish when you move the flame away.

What I did was heat up an area then use a scraper to scrape it off.

I would look for some high temp plastic scrapers so to not scratch the paint.
 
If it's cold, the air chisel with a wide blade works really good, like in post #6. It's way faster than any other method i've tried. Otherwise, like above, a torch and a steel putty knife will work. It actually works better when you have two people. One heating with the torch turned way up, and the other one following along scraping.
 
Is started with a old HF oscillating tool and scraper blades. Works well. But i burnt that up and switched to pneumatic mini needle scaler which even better. No chemicals etc and the material lands dry and can swept or shop vacuumed up. But my car was also on a rotisserie. Where a dust mask or other APR for sure.

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It can even help find rusty metal under that spray. Like when it blew through this spot when used in the trunk!

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I posted this April 30, 2020
Removing 55 year old undercoat from your restoration is, to say the least, something that can be time consuming and just "sucks canal water." I've watched videos and read articles about it. I've used an air scraper, (fair) heat (fair) paint stripper (nope) and even oven cleaner to try and expedite its removal. I would like to share something I discovered by doing something "just for the hell of it." (of course I may not have discovered something that has already been discussed on the forum, if so, I haven't seen it.) I "generously" sprayed (wet) my fender wells with "Goo Gone Automotive Spray Gel," just to see what would happen. It was late in the evening so I decided to let it stay on over night. The next day I was blown away about how easy it was to remove the under coating. I was so impressed I had to make this little video to share. (Let me add...I did a final clean up with my pressure washer, mainly to get rid of the residue)
Norm
1965 Barracuda restoration.
 
Sucks canal water. :lol:
I wonder if it would have been any easier if you hadn't waited overnight. maybe just a few hours? It might have been a little "wetter' and been even easier to remove.
 
I second the Goo Gone. I sprayed on the inside of my fenders and let it sit for a few hours and it came right off. Then hosed it down! Works great!!
 
I tried using a heat gun and then a propane torch on the Dart, nothing would touch that crap. I got a needle scaler and that did the trick. This was easily the most filthy job I've done on the car. I had a face shield, eyewear, a quality dust mask, hat, long sleeves, and still it got everywhere. However, when done it sure looks nice!

The grey area is cleaned off of old undercoat, the brown is the primer.

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Shore looks purdy all finished up with new undercoat!

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Could be factory, dealer, end user. Getting it off though, there's really no "easy" way. It's gonna be some work.
 
Fuel line off, first coat of Goo Gone left on a few hours and scraped. Ugh...new fuel pump, hard lines cleaned out from carb to fuel pump, as well as new fuel hoses, clamps and filter. Second coat of Goo Gone on. Letting it set overnight, see if it'll soak through the thicker coating. Found some rust the undercoating was hiding, it probably did more to trap moisture than actually prevent it...
 
Man, wish the underside of mine looked anywhere close to you guys! I'm just not going to blow it apart, I did that to my 38 Chevy...ask me how close I am to finishing THAT project!
 
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