wtf baked my valve covers have blisters
04-25-2016, 07:48 PM
#41
Oil Producer
Thread Starter
i am 99% sure that its oil in the metal. there is a pic upthread of oil coming out a pore after being sanded and washed.
if anybody tries this, it is actually very possible and easy but you must strip, clean, wash with soapy water then bake in oven or bbq for a while and u will most likely see oil come outpores.
then wash in hot soapy water again.
then prime, paint with high temp enamel of your choice. i let that sit for a month because it took me that long to get to reinstall. the can said to wait a few days. then i got a can of 2k clear, the kind u have to pop the bottom up and it releases the hardner then you have a 24hr life to the can. its about 20$ for the 2k clear can. spraymax is the brand in the us. in canada i used a local sourced can from a body shop supply store.
i coated the bejesus out of mine with clear coat in multiple thin coats. dont allow runs or you will want to sand and recoat which would suck.
mine sat for a long time before getting them on the car. once they warmed up on the car i could smell them curing a bit more. i also smelled the black head paint that i put on and saw it its fjmes come off.
i heat cycled the engine and let it cool. looks excellent!!!!!
i also used my kids paint brushes to touch up the black on the emblem. that got clear coated seperatly. then i saw cliff harris had jb welded his emblem on so i sanded the clear with rough 60 grit on the mounting point of the vc and did same on back of emblem. light jb weld coat so it would squidge out the edge.
have a look.
04-25-2016, 08:31 PM
#42
Burning Brakes
Cheap porous castings hold contaminates. When baked, it bubbles up to the surface.
04-25-2016, 09:00 PM
#43
Oil Producer
Thread Starter
not quite sure on cheap being the reason. my understanding is that magnesium as a metal is lighter and more porus.
ill report on mine later as it proceeds but the trick is to bake them before you paint and get any volatiles out and wash/scrub with hot soapy water and a brush.
Last edited by VikingTrad3r; 04-25-2016 at 09:00 PM.
04-26-2016, 06:50 AM
#44
baking valve covers is nonsense and surely not the "key." if anyone is experiencing paint problems, it's because they're not getting the castings perfectly clean initially. I have restored, reconditioned, or painted, close to a dozen sets of magnesium covers, and have yet to bake these things in an oven or the back yard barbecue. here's a proper link for cleaning and refinishing magnesium castings.
https://books.google.com/books?id=cA...nesium&f=false
nowhere will you find a "baking" step!
my personal "KEY" to painting magnesium is a wash with tri-sodium phosphate, a thorough detergent wash and rinse, and a final solvent wipe. the base prime coat should be an acid etching primer, followed by your choice of topcoat. I have never experienced paint failures due to surface contamination. you bake cookies, not valve covers. sorry for the rant, and no flames, but i'm amazed how some of this gets started and then "propagates."
https://books.google.com/books?id=cA...nesium&f=false
nowhere will you find a "baking" step!
my personal "KEY" to painting magnesium is a wash with tri-sodium phosphate, a thorough detergent wash and rinse, and a final solvent wipe. the base prime coat should be an acid etching primer, followed by your choice of topcoat. I have never experienced paint failures due to surface contamination. you bake cookies, not valve covers. sorry for the rant, and no flames, but i'm amazed how some of this gets started and then "propagates."
Last edited by Joe C; 04-29-2016 at 04:02 PM.
04-29-2016, 03:43 PM
#45
Burning Brakes
Yes, a good cleaning with something like TSP and a conversion coating immediately after cleaning/stripping is all you need. The problem you're running into is that as soon as Mag is stripped, it starts corroding. If you just paint over it, it will keep corroding and produce a gas under the paint as part of the corrosion process that the paint will trap underneath.
And, NEVER, use a wire brush on Mag. You will embed particles of a dissimilar metal in the (softer) Mag and will get small bits of galvanic corrosion all over the place. Use a non-metallic abrasive to sand/strip.
A good conversion coating is something like this from aircraft spruce:
https://www.aircraftspruce.com/pages...otesurface.php
If you need to fill pores, you can use "all-metal body filler", which is aluminum based and won't react with Mag.
All of this holds for Aluminum (for those of you with boat outboards/outdrives), too, although it's not as reactive as Mag.
And, NEVER, use a wire brush on Mag. You will embed particles of a dissimilar metal in the (softer) Mag and will get small bits of galvanic corrosion all over the place. Use a non-metallic abrasive to sand/strip.
A good conversion coating is something like this from aircraft spruce:
https://www.aircraftspruce.com/pages...otesurface.php
If you need to fill pores, you can use "all-metal body filler", which is aluminum based and won't react with Mag.
All of this holds for Aluminum (for those of you with boat outboards/outdrives), too, although it's not as reactive as Mag.
08-08-2016, 03:53 PM
#46
Oil Producer
Thread Starter
joe i agree about baking the paint
howver, heating up these magnesium valve covers on my bbq, even after extensive sanding hot water washing with soap
still produced small oil spots coming out from the metal.
i agree on baking the paint. not neccescary and besides the engine bay nicely cures it anyway.
there is a post upthread where i summarized the final process that ended up working. the 2k clear is a great ending step as it created a very glossy and hard commercial finish.
when reinstalling everything i was careful to protect the vc's especially those darn intake runner bolts and also the dizzy clamp.
now after being done for many months the finish still looks great and the coating has hardened considerably.
cheers.
howver, heating up these magnesium valve covers on my bbq, even after extensive sanding hot water washing with soap
still produced small oil spots coming out from the metal.
i agree on baking the paint. not neccescary and besides the engine bay nicely cures it anyway.
there is a post upthread where i summarized the final process that ended up working. the 2k clear is a great ending step as it created a very glossy and hard commercial finish.
when reinstalling everything i was careful to protect the vc's especially those darn intake runner bolts and also the dizzy clamp.
now after being done for many months the finish still looks great and the coating has hardened considerably.
cheers.
baking valve covers is nonsense and surely not the "key." if anyone is experiencing paint problems, it's because they're not getting the castings perfectly clean initially. I have restored, reconditioned, or painted, close to a dozen sets of magnesium covers, and have yet to bake these things in an oven or the back yard barbecue. here's a proper link for cleaning and refinishing magnesium castings.
https://books.google.com/books?id=cA...nesium&f=false
nowhere will you find a "baking" step!
my personal "KEY" to painting magnesium is a wash with tri-sodium phosphate, a thorough detergent wash and rinse, and a final solvent wipe. the base prime coat should be an acid etching primer, followed by your choice of topcoat. I have never experienced paint failures due to surface contamination. you bake cookies, not valve covers. sorry for the rant, and no flames, but i'm amazed how some of this gets started and then "propagates."
https://books.google.com/books?id=cA...nesium&f=false
nowhere will you find a "baking" step!
my personal "KEY" to painting magnesium is a wash with tri-sodium phosphate, a thorough detergent wash and rinse, and a final solvent wipe. the base prime coat should be an acid etching primer, followed by your choice of topcoat. I have never experienced paint failures due to surface contamination. you bake cookies, not valve covers. sorry for the rant, and no flames, but i'm amazed how some of this gets started and then "propagates."
08-08-2016, 04:09 PM
#47
joe i agree about baking the paint
howver, heating up these magnesium valve covers on my bbq, even after extensive sanding hot water washing with soap
still produced small oil spots coming out from the metal.
i agree on baking the paint. not neccescary and besides the engine bay nicely cures it anyway.
there is a post upthread where i summarized the final process that ended up working. the 2k clear is a great ending step as it created a very glossy and hard commercial finish.
when reinstalling everything i was careful to protect the vc's especially those darn intake runner bolts and also the dizzy clamp.
now after being done for many months the finish still looks great and the coating has hardened considerably.
cheers.
howver, heating up these magnesium valve covers on my bbq, even after extensive sanding hot water washing with soap
still produced small oil spots coming out from the metal.
i agree on baking the paint. not neccescary and besides the engine bay nicely cures it anyway.
there is a post upthread where i summarized the final process that ended up working. the 2k clear is a great ending step as it created a very glossy and hard commercial finish.
when reinstalling everything i was careful to protect the vc's especially those darn intake runner bolts and also the dizzy clamp.
now after being done for many months the finish still looks great and the coating has hardened considerably.
cheers.
08-08-2016, 05:14 PM
#48
Oil Producer
Thread Starter
all good id never take it as that.
you could be right about the bbq lol
i have my 87 to do this time ill report on if similar results are had.
you could be right about the bbq lol
i have my 87 to do this time ill report on if similar results are had.
08-09-2016, 04:01 AM
#49
Safety Car
baking valve covers is nonsense and surely not the "key." if anyone is experiencing paint problems, it's because they're not getting the castings perfectly clean initially. I have restored, reconditioned, or painted, close to a dozen sets of magnesium covers, and have yet to bake these things in an oven or the back yard barbecue. here's a proper link for cleaning and refinishing magnesium castings. https://books.google.com/books?id=cA...nesium&f=false nowhere will you find a "baking" step! my personal "KEY" to painting magnesium is a wash with tri-sodium phosphate, a thorough detergent wash and rinse, and a final solvent wipe. the base prime coat should be an acid etching primer, followed by your choice of topcoat. I have never experienced paint failures due to surface contamination. you bake cookies, not valve covers. sorry for the rant, and no flames, but i'm amazed how some of this gets started and then "propagates."
08-09-2016, 07:10 AM
#50
(no flames) the OP had an issues with repaint, not because of engine oil, but because of hamburger grease. one minute you're frying up bubba burgers, and the next minute you're prepping parts for paint in some dirty, greasy, backyard BBQ grill -
VT3, if you're going to repaint your 87's valve covers, DON'T prep these things in your backyard grill. your not driving out engine oil, your driving in hamburger grease. remember, you bake cookies, not valve covers!
- 
Last edited by Joe C; 08-09-2016 at 09:14 AM.
08-09-2016, 02:53 PM
#51
Safety Car
one, I have powder coated in the past. "apparently" you've never "properly" prepped metal for paint. two, I have refinished, probably a dozen sets of covers over the last 20 years, all done with a thorough cleaning and prep, and have yet to have an oil contamination issue. I don't understand why some people think magnesium (alloy) VC's can't be re-painted, and this stuff soaks up oil like a sponge. granted magnesium is somewhat porous - the actual term for magnesium porosity is, I think, "foam" and the percentage, of this "foam" can be adjusted by the composition of the alloying material. there is a balance between porosity, strength, and weight between the different alloys. the real shortfall with magnesium alloys has to do with corrosion resistance, and that's one of the reasons GM painted the things to begin with - the other, they are pretty sad looking castings. hence the sandy-textured topcoat. in one of my previous posts, I attached a link to properly cleaning magnesium prior to refinish. i'm not saying powder coating is bad, what I'm saying is if done properly, VC's can be re-painted without problems. powder coat or paint - to each his own. I personally prefer paint for the originality factor, and the constant learning and challenge to replicate original factory finishes. (no flames) the OP had an issues with repaint, not because of engine oil, but because of hamburger grease. one minute you're frying up bubba burgers, and the next minute you're prepping parts for paint in some dirty, greasy, backyard BBQ grill - VT3, if you're going to repaint your 87's valve covers, DON'T prep these things in your backyard grill. your not driving out engine oil, your driving in hamburger grease. remember, you bake cookies, not valve covers! -
08-09-2016, 03:31 PM
#52
This isnt an arguement about powder coating or spray painting. My comment was in regards to the extra step that is done to prepare a part. Pre baking is a common step that every powder coating business uses. And why do you think that is? Its because it outgasses contaminants that are IN in the metal. Then after those contaminants are brought to the surface they surface clean them again. I think you been lucky and havent dealt with any seriously contaminated valve covers.