Why did my painted LS6 manifold's paint crack?
#1
Why did my painted LS6 manifold's paint crack?
Opened my hood after my first couple of rides since the car has been back together to see that all the paint on my LS6 manifold has started cracking I'm not sure why this happened, I sanded down the entire manifold with 220, then 320. Scuffed with SEM soap and a red scotch brite then adhesion premotered before laying down DuPont 2k primer. Sanded the primer with 600 for base and clear coat. So maybe someone knows what went wrong and can correct me so this doesn't happen again. Thanks
#4
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Maybe you need a flex agent in the paint. Like you would for a bumper, because I doubt the intake got hot enough for it to fail. Just a guess though I really don't know how much expanding and contracting one of these intakes do.
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#8
Staging Lane
don't use the plastic promoter! your going to have to sand it all done sand it with 180 scuff it down , clean it with a dewax and degreaser then lay down some nice coats of primer! if you can see the sand marks after it dries take some 400 and wet sand it smooth. then you can either lay down your base coat or give it another coat of primer that's up to you then it will stick to the plastic and bond together and heat should not effect it!
#9
don't use the plastic promoter! your going to have to sand it all done sand it with 180 scuff it down , clean it with a dewax and degreaser then lay down some nice coats of primer! if you can see the sand marks after it dries take some 400 and wet sand it smooth. then you can either lay down your base coat or give it another coat of primer that's up to you then it will stick to the plastic and bond together and heat should not effect it!
Thanks
#10
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You have to use some kind of promoter, you can't just paint on plastic. What kind of promoter did you use? The bulldog stuff that's in the writup in the sticky? I've seen some primers separate (between itself). Not epoxy primer, though.
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Wondered about too thick as well, look at third pic, look how much it shrunk up!
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had a chat with my boss today actually. he was saying using wax & grease remover on plastic is not a good idea because it pulls the mold release agents and any other oils to the surface. only supposed to use water based stuff or just soap and water
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That's scary. Hope it never happens to mine. Previous owner had it done in GM Sunset Orange Metallic. I've never painted an intake, but I know, in the past any success I've had with painting plastic, the material had to be highly scuffed.
#19
just had a thought...dont most of the aresols say to do a very light coat of adhesion promoter? possible issue?
Yes they do. On the can it said first coat is a dust coat, then the next coat is a medium wet coat and you let it sit for 15-30 minutes, which I did.
Wondered about too thick as well, look at third pic, look how much it shrunk up!
Yes they do. On the can it said first coat is a dust coat, then the next coat is a medium wet coat and you let it sit for 15-30 minutes, which I did.
Wondered about too thick as well, look at third pic, look how much it shrunk up!
Anyone else have any ideas?