Black Undercoat Removal

[rothaus]

I'm in the process to get my 70 911T ready for Painting, and the car has a layer of this ugly black undercoat in the wheel wells and underbody. Somebody sprayed it over the original factory coating. Is there a good efficient way to get it off ?

Whatever I try it also damaged the factory coating.

Thanks for any input on that.
Engelbert

[Dpmulvan]

Did you try a heat gun? Just a thought

[rothaus]

With heat I also destroy the factory coating.

Thanks for the input
Engelbert

[turbo owner]

Try WD-40, let soak and wipe it off.

[962porsche]

your looking at allot of work no matter what method you pick .
that crap is not made for cars that's why NO auto maker uses it .

we use RM 900 in a pump up sprayer and soak the crap out of the area were it is .
wipe off with lots and lots of clean paper towels .
lay plastic sheeting under the car so you don't make a total mess of the ground / floor .

if the hole underside and wheel houses are done you will go thru about 2 Gal. of preclean-o /900 .

on some cars when some dumb ass coated the hell out of the car with that crap we just remove all the chip guard right down to bare metal and start again .
it's 3 days labor to try and remove just the undercoating or a days labor to just remove the undercoating with the chip guard to bare then re chip guard every thing .

one problem is some times the black undercoating will stain the chip guard so even after you remove it the chip guard still will not have the OE look it should .

[rothaus]

Hi 962porsche,

Looks like just thinking about this stuff makes you mad. I feel the same way.

Thank you for your input.
Engelbert

[962porsche]

it sure in the hell does !
people have no idea what a PITA that crap is like to remove . the worse part is it does nothing at all .
it offers no extra protection . it never drys and if you get solvent on it then it just makes a mess .

if this is your 1st go around with it then think about dealing with countless cars I have had to deal with that crap on it .

[47silver]

Horrible job. Had fenders bead blasted. Diesel fuel helped. Then wire cup brushes. Time consuming and dirty

[rothaus]

I could not find where to buy the RM 900. However, I got a good tip about using Kerosine. Which I had already at home. It works but slow, however, that's better than anything else I have tried.

Here are a few sections I cleaned up. I sprayed it on with a spray bottle, and then used a brush to loosen it up, and wiped it off with rags. I put a plastic on the floor and some oil try on it.



It looks like the factory chip guard is light gray.



Thanks for all the tips.

Cheers
Engelbert

[962porsche]

all you need is a product that breaks down tar as that is what it is .
the fun is getting out from inside the texture of the chip guard .

[turbo owner]

Originally Posted by 962porsche

all you need is a product that breaks down tar as that is what it is .
the fun is getting out from inside the texture of the chip guard .

Pressure washer will do it

[JohnJL]

Originally Posted by turbo owner

Pressure washer will do it

Yes, this. With a bit of pressurewasher degreaser. Hook up to your hot water for extra quick cleaning. Just did this Monday.

[962porsche]

only to a point will a pressure washer remove it . we clean the hell out of the tar with 900 then soak every thing again and power wash it as the last step . but more often then not there will still be some of that crap left in the nooks and crannies .
no matter what you do it's a sucky job removing that crap .

[turbo owner]

Originally Posted by JohnJL

Yes, this. With a bit of pressurewasher degreaser. Hook up to your hot water for extra quick cleaning. Just did this Monday.

Dawn dish soap does a great job for final clean up, mix strong in a spray bottle to apply. Scrub brush it first then wash, repeat as necessary.

[Keith l]

Try Eastwood,s "UNDERGONE" in the aeosol cans-works great.

[rothaus]

OK, I get most of this stuff off.

Here is partial success


That was is still left, is like over spray paint.


Whoever worked on that car and installed a new front suspension pan, sprayed that black stuff just over the blank metal.


Same thing for the door past replacement


Here is the thread of my project.

My 1970 911T project

Cheers
Engelbert

[Cairo94507]

Glad you took all that stuff off to see what was underneath. Now you can do it correctly and sleep better at night knowing it was done right. Good work.

[ed317]

I have also used Aircraft stripper, no longer available in California.
Use in a well ventilated space and don't smoke.
Like everyone says, dirty job but needs to be done, I would strip to bare metal then start over.
Good luck, Ed

[rich]

Looks like a job for Mike Rowe!! I feel for you man!

[TMo]

I've used kerosene followed by Dawn dish soap in the past. It's not fast, but it is effective.

Kerosene and scrubbing with a stiff bristle plastic brush, thorough rinse with kerosene followed by wash and scrubbing with a medium/soft bristle brush and the Dawn.

I'm sure there are more harsh chemicals that could make quicker work of it, but I don't feel like I'm actively giving myself cancer with gauntlet gloves and the above treatment.