How Do I remove this undercoating

[WyldBill]

Hey guys it looks like I've got in a little over my head I have a 65 Sport Fury an it has some kind of undercoating on the bottom my original thought was to paint the bottom with Rust Bullit with a black outer coating the problem is this undercoating seems to be in one of two states falling off or stuck extremely well as you can see a large portion of it has fell off but the remaining is stuck really well. I've been trying to get this stuff off all weekend with not much luck. I've tried professional strength goof off and aircraft stripper then hitting it with a pressure washer as well as a heat gun and scrapper and a hand grinder with a wire brush. I did take a chunk and put it in as cup of gasoline and it turned into goo but I'd rather not use that as a solvent. I'm trying to do this project myself as much as i can. But I'm not getting anywhere very fast. Has anyone ever ran into this before if so any advice would be greatly appreciated.

 

[commando1]

I can't say this is the brightest thing I have ever done but I found heating it up with a propane torch makes that stuff literally fall off using a putty knife.
And I'd do it again only this time wearing wearing a hard hat...

.

 

[polara71]

When I was 18 I laid on my back and wire wheeled the belly of a 1971 Polara four door. ...... DONT do that unless you're 18, and even maybe then.


Good luck, whatever method you use

 

[monaco75]

I agree with Stan. The propane torch, and scraper work the best in my experience. After the bulk is off, go over with a wire wheel.

 

[Zymurgy]

Not any better, safety wise, but I have had leaky gaskets on my fuel tank. Gasoline takes it right off, to shine metal.

I would think there would be other less flammable options as a possibility.

 

[67-Fury]

When I was 18 I laid on my back and wire wheeled the belly of a 1971 Polara four door. ...... DONT do that unless you're 18

....What about 21? lol.

 

[Wildaugust]

I've tried Brake Cleaner and Gasket Remover aerosol spray to remove undercoating from parts and specific areas under my car. Both of those had no effect. I haven't tried gasoline. If you're going to use gasoline, it would be best to do it outside instead of indoors, IMO.

 

[MrMoparCHP]

I have great luck with a heat gun (not a hair dryer) and a putty knife.

I kept the putty knife hot by heating the area just ahead of it and almost as fast as i could scrape it off it came off.


Alan

 

[VALNUT]

I think its tar based so heat will always work. A less flammable option to gasoline is kerosene. Ive used heat on a valiant that was caked in it and then clean up with kero. works a treat.

 

[polara71]

....What about 21? lol.

No....things were starting to hurt by then

 

[70bigblockdodge]

Heat gun cheap one at harbor freight should last long enough to do at least one car and less flammable than the torch which works well also.

 

[Ironwolf]

I would also use one of these face shields .........

 

[rexus31]

Why fight it? It's a good protective coating. Rust Bullet the bare spots and overcoat the entire underside with 3M's undercoating in aerosol cans. That's what I did on my 300 'vert. My car must have gotten the deluxe treatment at the dealer because that **** was EVERYWHERE; caked on the underside of the trans, the oil pan, gas tank, suspension. Those areas were dealt with but I wasn't about to spend countless hours on my back scrapping that crap off. And for what? Who's going to look at it? Your time and energy are better spent making other parts of your car perfect.

 

[commando1]

I'm shocked. I would have bet my life that I would have been able to see my reflection on your underbody.
But beautifly done, none the less.

 

[polarus]

When I was 18 I laid on my back and wire wheeled the belly of a 1971 Polara four door. ...... DONT do that unless you're 18, and even maybe then.


Good luck, whatever method you use

X2

 

[rexus31]

I'm shocked. I would have bet my life that I would have been able to see my reflection on your underbody.
But beautifly done, none the less.

Exactly the reason why a presentable tidy up will suffice; no one will know. Our cars simply aren't worth enough to justify the time and energy.

 

[Big_John]

Heat is about the only good way. Propane torch with a flame spreader is my weapon of choice.

 

[WyldBill]

I think Rexus makes a lot of sense i think i can blend it all in and make it look pretty good the truth is that this crap has kept it from rusting for 50 years it must be pretty good ( i haven't found any evidence of rust underneath the car) and i can testify that it's not falling off anytime soon. I appreciate everyone's suggestions but i think the truth is this stuff isn't supposed to come off ever and at this point if what remains hasn't came off then it;s not coming off without tons of work

 

[70bigblockdodge]

You will know if it is rusty behind it, that's when it falls off.

 

[Samplingman]

You will know if it is rusty behind it, that's when it falls off.

Exactly, and that's what I'm doing with mine. Scrape the bare/loose spots, take care of the rust and blend. The only panel I cleaned completely was the trunk pan replacement. I had to do a lot of welding and you really don't want this stuff to catch fire where you can't reach it.