Media blasting engine bay.

[tyson]

This winter for the 240Z I want to strip the engine bay, inner front fenders (lets just say the entire front unibody) and most of the trans tunnel, seam weld and do some smoothing.  I think I might relocate the battery as well (I'm undecided right now).

 

I've read about a million posts on different forums about doing this on various makes, but I'd like to pick the brains of people who have done it on Zs.

 

It's going to be winter in Minnesota, so I'll be working in a garage with a kerosene heater.  To keep flash rust down from the moisture/condensation I'm thinking of doing about a 1' tall x 2' long section at a time (give or take), cleaning, then priming with a weldable primer and moving on to the next section.  

 

I'll be using my ~30 gal 2hp compressor, it does about 5.5cfm at 90psi.   For the gun/hopper I've read good things about the cheapo harbor-freight, only complaint is people having to fill the hopper (but since I'm doing just the engine bay, I don't see it being a huge annoyance).

 

Dust is also an issue, since I will not be able to have the garage door open more than a crack.  I'm thinking of using plastic bead to first strip the paint, and then using silica to attack rust when I find it, trying to keep the blast nozzle at an angle instead of at a 90 degree to avoid any potential of warping/pitting.   I plan on sifting the media and reuising, I have an idea for a nice containment area.

 

I'd much rather spend a day or two getting covered in dust rather than spend a weekend lightheaded, splashing chemical on and cleaning up the goopey mess under the car.

 

Does anyone have any tips or suggestions?   Will the plastic media give me a good texture for paint, or should I lightly go over it with silica afterwards?

Edited October 15, 2013 by tyson

[jt1]

I can't comment on the plastic media since I haven't used it.

 

So far as the sand, i think your plan is workable.  You need to pay a lot of attention to sealing up the cabin of the car.  Sand will get everywhere, I mean everywhere.  You need good eye protection, some type that seals to your face with a gasket.  Moto x googles worked for me.  You may want some type of air supply.  This can be as simple as a vacuum cleaner.  Prepare to be filthy.  Sand in your hair, your ears, the crack of your a**, everywhere.  However, the results are very nice.

 

jt

[tyson]

Cool.  My plan is to build a containment shield out of PVC tubing and blue tarps, I'll build it to wrap around the front end of the car.  I was thinking a shop vac on one end, and a blower fan on the other to try and keep the dust moving.

 

Good call on the eye pro!  As for dust getting everywhere, it can't be any worse than being in Kuwait during a dust storm hehe.

[socorob]

You should use a supplied air respirator with sand. Silicosis is very bad. A friend of mine does media blasting. He uses plastic, sand, and glass. Plastic won't remove rust, but its a little cleaner and he does that in a booth. He is able to scoop it up with a shovel and run it through a filter to reuse it. He will then use sand on the rust spots. The glass is nice. It is mixed with a liquid solution so it makes no dust and you barely need any ppe. I'm not sure how much a setup for home use is, but there's a video of someone doing it in a garage and it only makes a mess a few feet around the perimeter of the car. It doesn't go everywhere.

[tyson]

You should use a supplied air respirator with sand. Silicosis is very bad. A friend of mine does media blasting. He uses plastic, sand, and glass. Plastic won't remove rust, but its a little cleaner and he does that in a booth. He is able to scoop it up with a shovel and run it through a filter to reuse it. He will then use sand on the rust spots. The glass is nice. It is mixed with a liquid solution so it makes no dust and you barely need any ppe. I'm not sure how much a setup for home use is, but there's a video of someone doing it in a garage and it only makes a mess a few feet around the perimeter of the car. It doesn't go everywhere.

 

Hmm, I'll have to look into that liquid setup as it sounds interesting.

 

PPE is a must.  Both my grandfather and my father died early due to lung problems, grandpa due to his years as a mason, my father although diagnosed as idiopathic it was likely his years as a smoker.  I usually use canister style respirators whenever possible just to make sure I'm on the safer side.

 

Does anyone know if plastic media blasting will give me a suitable surface for the primer to adhere to?  Maybe I'll look into just doing glass bead and silica instead of the plastic?

[socorob]

Its like this, probably something you cant do yourself, but in the time he did the whole car, i doubt you'll have 1 door done with a small home sandblast setup. Compressor is a must, little home ones won't handle it at all. If you have a large tank twin cylinder, you may be able to sand blast but you'll be stopping a lot waiting for the compressor to catch up. It needs massive amounts of air.

[EF Ian]

Dust really does get everywhere, in any gap, hole, anywhere open, blasted my bay recently, the rest of the car was well covered but dust still made it the whole way underneath and into the chassis at the back, on top of the fuel tank, everywhere, even inside somehow, though it was well sealed but it still found a way in somewhere.

[proxlamus©]

the video above with water blasting...  is $2500 for the blaster.

 

    Ill be blunt.  Ive blasted my Z at home with soda and nickel slag with a 90 gallon compressor.  Ive done seam welding and grinding.  I will NEVER do it again.   Either rent a compressor and heavy blaster or drop it off at a shop.  Trust me. 

[socorob]

Without the proper equipment it will work you really hard.

[Zinpieces]

I recently had my 240 shell done by a local "Green Earth" glass slurry. The results were fantastic! The cleanup was a real chore. It took me three days to get the glass out of the car. I don't mean the occasional wisp of powder I mean the five pound clumps. It was worth it, but it was a real chore, a lot of rotating on the rotisserie a lot of tapping, banging, vacuuming, and blowing. If I had done only the exterior the cleanup would have been a breeze. I did everything inside and out. Probably should have just POR 15'd the interior but I am just a little anal when it comes to rust. The job was done on a hot humid day and the skin did start to flash almost immediately. I spent two days with  a DA smoothing the body and then shot on epoxy primer sealer inside and out. Painted the shell on my rotisserie which made good coverage a breeze. Plan on sanding the body the glass will leave a rough surface. The inside and the underside got a quick scuff and liberal scrub with wax and grease remover.

[Tony D]

I sandblasted my 73 engine bay in 1985.

After recovering from the silicosis I gave myself I painted it.

 

It looked great.

 

To this day, I still get sand in the heater system. I would NEVER do it again!

 

I would chemical strip with water-based stripper, and confine any blasting to a self-recovering unit with mask to recover media and spotblast corrosion.

 

I bought the larger HF Pressure Pot for soda blasting and use it outdoors...with a mask. Tops better than any suction feed gun, and works way better with limited volume compressors like yours.

 

 

My advice on your compressor: see if you can find more tanks to add volume and use a pressure pot style blast setup outdoors, or the spotblaster mentioned.

 

Never, never, never ever again. Goddamn sand. It IS WORSE than Kuwait in a sandstorm! Trust me on that!

[Tony D]

Mind you, I actually own one of those IR Diesel Powered compressors and two 300 gallon tanks... For frames on domestic crap and the like, I will get guys together and have a "blasting day" in the back yard. Split the cost of a commercial pressure pot and hood/ventilator and piss off the neighbours starting around 7AM

 

For chassis parts, castings, crap like that it's great.

 

I'd never do my engine bay that way again.

[RebekahsZ]

The problem I have with blasting and chemical stripping is the loss of all factory anti-rust coatings on the metal. And yes, the z car does actually have some. After stripping my car to bare metal 20 years ago, any tiny scratch in the paint immediately goes to rust. If I ever do a z again, I will limit old paint removal to only that necessary to get new paint to bond. And as for cleaning: never sand blast a fuel tank. Learned that the hard way too. Just scuff up the existing paint with sand paper and paint over it.

Edited November 16, 2013 by RebekahsZ

[s14kouki10]

The problem I have with blasting and chemical stripping is the loss of all factory anti-rust coatings on the metal. And yes, the z car does actually have some. After stripping my car to bare metal 20 years ago, any tiny scratch in the paint immediately goes to rust. If I ever do a z again, I will limit old paint removal to only that necessary to get new paint to bond. And as for cleaning: never sand blast a fuel tank. Learned that the hard way too. Just scuff up the existing paint with sand paper and paint over it.

Did you apply an epoxy primer to the bare metal?

Edited November 20, 2013 by s14kouki10