I am about ready to removing the under coating,I have used a putty knife to do a test the thing is the PO also used some kind of liquid rust check, the good news if there is such a thing the hard stuff is soft.OK so what can i use to get it off,this stuff is like oil,any tips will help greatly.

I have used a hot water pressure washer and was able to get 100% off without damaging the metal or original paint/over spray.

I used some gasoline in a pump up sprayer to soften up the hard stuff. In less than 4 hours I had the bottom of my car spotless, clean enough to eat off of.

Rent one, you won't be sorry and you can move on to other more important things on your car. Pictures later.

Well thats a good tip this washer does it do the heating up for water?

This is the machine I use. It uses #2 diesel to heat the water to near 212° and moves 4.5 gallons per minute at 2000PSI.


I used it to clean the engine bay first. Sure I removed plenty of factory undercoating, but there was also plenty of road tar and dirt mixed together from 30 years of use that was just as tuff as the factory undercoating in places.



Notice how I have just done the top side so far, I flipped the car to get it from the other angle. Never bent over the whole time.



I have been using a pressure washer like this one at work since the 80s. I bought this one for my home over 10 years ago now, use it year round at home for everything.

Man I wish I would have this.. would have rented one.. I used a torch..putty knife..and wire wheeel on a drill....

very nice you know what your doing.

Thanks, I used it to strip my doors on a different car. MY gold 71.




A heck of a lot easier than sanding off the old paint, especially in the door jambs.



June 2015, Thurs before the Nationals because that's where were going in the pouring down rain!

In 1976 or so my first "real" job was working at a British car and motorcycle dealer and he raced a Ford Cortina. One of my first jobs was to remove the undercoating from the car with a putty knife and a propane torch. I had to lay on my back on a creeper and it was one of the nastiest jobs I ever did, great way to find out I didn't want an automotive career in my future... It did work just fine, but I would find a better way if I did it again.

I did it that way on 71 challenger I had around 1983, I got it off with torch and a putty knife, well most of it. I never did get the car back together and sold it and many NOS parts for it around 1988 to go drag racing. Man did I sell those NOS parts cheap compared to today. I sold them for more than I paid for them, thought I was doing good, it was still cheap.

Yep, same here, steam is the ONLY way I'd ever do this job. 3 hours of wet and dirty, all done!

I remove this stuff often for customers. it doesn't have to be complicated and I don't think you need to spend hours with a pressure washer just to spend hours with a sander afterwards.
media blasting has come a long way in the last few years and I am always amazed at people doing stuff the hard way to save $250 in blasting costs.

that being said I blasted a rx7 for a customer yesterday and he did an awesome job at removing the undercoating before i blasted. I asked what he used and he said dry ice. put it on and the undercoating froze and he swept it off.

dart

Chris,

I don't think media removal is a bad idea for some cars, but I wouldn't use it on my restoration projects simply because I like to reveal the factory paint application and undercoating pattern details without destroying them. So far steam cleaning is the best way I've found to do that.

If the body is mounted on a rotisserie, under coating can be removed by sand blasting. As a bonus, the surface is clean and ready for sealer.

A mobile blaster charged me $600 to strip my '71 Challenger, top to bottom.

Make sure the blaster knows what he is doing, as sheet metal warps easily. The worst part is blowing out/vacuuming out residual sand. In my case, it wasn't too hard, as I cut the bottoms off the quarters ahead of time.

I like steam cleaning because like Scott said, I can see what the car looked like new.

But the main reason for me is several,
So I don't have a bare car to deal with while I make rust repairs, the car is still protected while I do sheet metal replacement. It's plenty clean enough to weld on with minor clean up at the weld area with a flap wheel. Then when all that is done then I'll media blast it, the whole thing right before paint.

Saves me time and paint and grinding the primer off when I weld new sheet metal in. And then I only have to clean up media once and it sucks to have it in your frame rails when your trying to replace sheet metal on your car. Hate it on the floor of my shop.

Plus you can't media blast stuff like glass and you can't media blast around window regulators in doors either like I did with hot water. I cleaned out the window regulator tracks with steam.

And IMO media blasting off under coating causes much more stress on the metal than does steam cleaning, after steam cleaning it only takes a very light blasting to clean up. Less media and less to clean up too.

I blasted a lot of my gold challenger after pressure washing the whole thing first.

No oils got blasted into the metal or seams to come back later to haunt you because it was very clean before blasting. It took very little media, look on the ground and how close I am to my house, patio and garage. I used coal slag on the bottom and plastic media on the body.

And I didn't media blast the doors or the inside of the front fenders, only steam cleaned them. There too delicate imo to be blasting, plus they were not rusty on my 71. Only one way to get them this clean...and not have a bare part rusting as soon as your done blasting needing primer.

If blasting is necessary, I prefer to do so before metal work because cleaning is much easier when the quarters and rockers are cut open.

That is true. Another thing is, I use my 100 cfm compressor that I use to blast with to blow out the car. Not my wimpy 5 horse shop compressor.

i don't even waste my time blowing it out with a compressor..
i bought a stihl backpack blower for that task.

Heck yea! Bigger and badder is always better!

I Got a stihl hand held yard blower, just got it a couple years ago. Don't know why I didn't have one sooner?=real handy. We have tons of leaves to deal with in the fall too and I did them with a rake for 25 years.

Gary and Scott.....have either of you ever used a steam cleaner on a car that has been Ziebarted? My 68 Roadrunner got the full treatment, apparently when it was either new or close to new. It isn't rusty, but I bet it weighs 4K lbs. with all that stuff on it! I just want to clean what's on the bottom of the car, but want to strip it out of the engine compartment. I have access to a really good hot water pressure washer if it will remove said Ziebart goop.