Because they are made of magnesium, Is there any risk of fire when sandblasting 4.9 valve covers ?

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no only grinding.....which I took a wire wheel to mine before I knew what they were made of...no fire though but I wouldn't do it again

I found this about mag wheels.

http://www.roadsters.com/wheels/

"Magnesium is dangerous. If it ever catches fire, throw a bucket of sand on it and run for your life. When magnesium burns, it virtually can't be stopped. Small quantities of magnesium are used to make photoflash bulbs. Larger quantities are used to make bombs."

Maybe a paint stripper would be safer? I'm not sure what you could do about any pitting that has started.

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-Kyle
Email: kakagiraffe@gmail.com
Aim: Littlechugger
1988 Notchback 4.9 V8, 5spd Isuzu, Spec Stage 4
True Dual Exhaust, Delta Cam (212,000 Miles)
1992 Honda Accord LX (220,000 Miles) 5spd

ya even D rated fire extinguishers are hit and miss when it comes to putting out metal fires. If you just want to play it safe a soak in paint thinner will do it.

I used paint stripper and got as much off as I could that way and then used glass bead in my blaster to get the rest off. Worked well.

Jack

Yea before I knew that fact, I ground down my 4.9 valve cover while it was in the engine bay..I'm sure alot of shavings got thrown in the firewall insulation...greaaat. That valve cover is now gone, but still.

[This message has been edited by mattwa (edited 01-03-2012).]

Not sure if it is a fire hazard. However, you could hydro-blast them (sand and water). We have done that on the street rod bodies to keep the warping that comes from sandblasting down (the water keeps the metal cool enough to maintain form. Then etch wipe down and a compatible primer before the rust sets in ).

Please note that the fire hazard for magnesium is for "finely divided" - in simple terms, fine powder.

Solid, formed, cast magnesium is not much of a hazard.

Note also that many common materials are extremely flammable when "finely divided".

quote Originally posted by olejoedad: Please note that the fire hazard for magnesium is for "finely divided" - in simple terms, fine powder. Solid, formed, cast magnesium is not much of a hazard. Note also that many common materials are extremely flammable when "finely divided".

Yep. I've burnt magnesium for fun. In fillings, it burns pretty easily. In solid masses (like half of a chevy transfer case for example) it takes a good hot bon fire to get it to light...and even then it needs to sit in the fire pit for a good half hour to an hour before it takes off. Once a large mass lights, it's almost impossible to put out...convensional methods don't work and water can actually make it burn even hotter once it gets going. Fun stuff.

You've got to be very careful when sandblasting valve covers. If any stuck stray particles of abrasive get trapped/remain and end up in the engine it could cause severe damage, If you sandblast, keep the sand from the inner surface and try to powerwash afterwards. I play it safe and use paint stripper. It takes a few applications but it is safer.

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I found that straight lacquer thinner worked to dissolve the factory black paint. Soaking them took a while to work but it did the job. My valve covers ended up having oxidation under the paint and needed a good hand sanding to smooth things out. Before I knew about the "hazards", I used a dremel with a cut off wheel to remove those threaded pieces between the ribs of the back valve cover. Then I continued to use a had file and sand paper to achieve the look I was after. I didn't have any fires but swept up all the filings after I found out they were flammable and tried to light them (under safe conditions)...no success. I wouldn't stress yourself too much.

Fieroseverywhere bead-blasted mine and his and we didn't cause any fires. I even used a die grinder to sand off the paint off the center section and still didn't ruin anything. Like others have said, be careful, sweep away the dust and go slowly. Being ignorant and sanding away while smoking a cigarette might lead to a disaster, but simple safety precautions should keep you from burning down the house. Others have offered different methods to achieve the same results, so really, the choice is yours.

Thanks!!!

Josh

Some one recently told me that the decklid grills are magnesium. If this is the case I've not only sandblasted mine, I also ran one through the self cleaning cycle in my powder-coating oven at temps approaching 800 to bake the original coating off. Doh! Incidentally temps that high caused the grill to warp pretty severely so don't try this at home.

DF

edited to add:

I was once involved with a magnesium fire in a landfill. Even with 10 feet of compacted clay covering the burning material, flames could be seen coming through the dirt at night as well as a constant popping that could be felt in the bulldozer we used to keep it covered. It burned underground like that for 5 or 6 days.

[This message has been edited by Dave E Bouy (edited 01-04-2012).]

Degrease it, and wetsand it by hand. A little more time consuming but worth it in the end. No worries. Start with a heavier grit then move to finer grits. Like you would do anywhere else.

quote Originally posted by Dave E Bouy: Some one recently told me that the decklid grills are magnesium. If this is the case I've not only sandblasted mine, I also ran one through the self cleaning cycle in my powder-coating oven at temps approaching 800 to bake the original coating off. Doh! Incidentally temps that high caused the grill to warp pretty severely so don't try this at home. DF edited to add: I was once involved with a magnesium fire in a landfill. Even with 10 feet of compacted clay covering the burning material, flames could be seen coming through the dirt at night as well as a constant popping that could be felt in the bulldozer we used to keep it covered. It burned underground like that for 5 or 6 days.

If the decklid grills are magnesium, then I would say sandblasting them wouldn't be a problem, considering I tried to weld one and it didn't light up.

I was also involved in a magnesium fire... Actually I set it . I worked in a rail scrap yard and had just started there. They had a pallet of 50 lb sacks of magnesium fillings that were used to weld rail together. I was told to use a torch and cut the truck keys of the trucks so we could remove the wheels. First time ever doing it and the guy on the forklift gettin the trucks set me up next to this pallet of magnesium. A few sparks from cutting with the torch hit the pallet and the magnesium started burning. I freaked and tossed as many bags off the pallet as I could before the fire got to hot. Then jumped in a Bobcat with a bucket and burried the rest in dirt. Scared the crap out of me and I thought for sure that was my last day at that job. Luckily it wasn't.