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Thread: Manifold painting gone bad

  1. #1
    Join Date
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    Manifold painting gone bad

    I degreased, scrubbed and lightly sanded before applying a high heat primer. After my first coat of high heat enamel, I noticed it was reacting much like oil and water and no amount of paint will cover those spots.
    What's the issue and how do I resolve this? And please don't say blast and powder coat because around here, the cheapest quote I got was $800.

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  2. #2
    Join Date
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    850,76 2002 &530,84 633
    Either the metal was not cleaned well enough or the enamel reacted with the primer as discussed on Facebook. Did you use the same brand primer and enamel top coat? If so, then those two paints should have been compatible. If you used a lacquer based primer there's a good chance the enamel top coat reacted with it. As Steffen suggested, you might be better off using some stripper to remove all of the paint and then I would use some lacquer thinner to clean the metal really well before you try spraying it again. You need to use a durable epoxy based paint and I think it is the VHT brand that can be applied without the use of a primer.
    Last edited by JDP530; 02-14-2019 at 11:20 PM.

  3. #3
    Join Date
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    That painting problem is called fish eye.
    Here is the problem cause and solution from the professionals:
    https://www.sherwin-williams.com/hom...e-dir-fisheyes

  4. #4
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    Quote Originally Posted by m6bigdog View Post
    That painting problem is called fish eye.
    Here is the problem cause and solution from the professionals:
    https://www.sherwin-williams.com/hom...e-dir-fisheyes
    Thanks for sharing. It sounds like everyone is saying the same thing here. Use solvent in effected area, strip, clean and repaint.


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  5. #5
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    I bead blasted the manifolds after some intensive cleaning, painted the plenums black, and clearcoated the bare aluminum. Then I went back and highlighted the ribs and letters.
    IMG_20171222_190644383 (1).jpg

  6. #6
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    Quote Originally Posted by JDP530 View Post
    I bead blasted the manifolds after some intensive cleaning, painted the plenums black, and clearcoated the bare aluminum. Then I went back and highlighted the ribs and letters.
    IMG_20171222_190644383 (1).jpg
    I like the clear coat on the aluminum. Looks sharp.

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  7. #7
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    It turns out it was temperature related. As soon as I heated them up, the paint stuck just fine! See pic.

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  8. #8
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    Quote Originally Posted by nrp22101 View Post
    It turns out it was temperature related. As soon as I heated them up, the paint stuck just fine! See pic.

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    What was the temp difference between fisheye and success, if you can recall? Or did you just heat up the manifolds, rather than paint them in a warmer environment?

    Sent from my XT1710-02 using Tapatalk

  9. #9
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    Quote Originally Posted by Calypso8ball View Post
    What was the temp difference between fisheye and success, if you can recall? Or did you just heat up the manifolds, rather than paint them in a warmer environment?

    Sent from my XT1710-02 using Tapatalk
    When I painted them the first time it was around 55 F. which caused the fisheye. I heated them up with a heat gun and put the other on top of a portable radiator before the second paint.

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  10. #10
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    Quote Originally Posted by nrp22101 View Post
    When I painted them the first time it was around 55 F. which caused the fisheye. I heated them up with a heat gun and put the other on top of a portable radiator before the second paint.

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    Ah, ok, thanks, probably around 20-25 degrees warmer at least. That sure can make a difference for spray paint!

    Sent from my XT1710-02 using Tapatalk

  11. #11
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    Glad that worked out for ya! If I'd logged in sooner I would've suggested sending them down here. I've had two sets done at two different shops for about a quarter of that price and both shops did good work.

  12. #12
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    Here is another little tip for anyone painting the manifolds in the future. After cleaning and prepping the manifold, take a Q-tip and VERY LIGHTLY wipe a VERY THIN layer of Vaseline on only the raised top portion of the ribs and BMW. Paint the manifolds with your preference and let dry. Then, go back with a razor blade and scrape off the paint on the raised ribs and BMW letters. It comes right off! The Vaseline will not let the paint stick to the tops of the raised portions. Then, lightly sand with 1500 or 2000 wet/dry sandpaper on a flat block.

    Here is the last set I did on the 5.0. I used Harley Davidson Crinkle Paint (the same paint that they use on Harley motors - it is about $20 a can). This was the results using the method above:

    IMG_3675.JPG

    IMG_3714.JPG
    CSi #18 - Car & Driver Magazine 1994 actual test car
    -- Hellrot/Black-Gray (1 of 1 NA CSi color combination)
    BMWCCA E31 Chapter International Clubs Liaison
    North America Representative, 8er.or Board of Directors




  13. #13
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    Thanks, Roger; great tip!
    Your manifolds look terrific!

    --Steve
    SteveCT
    E31s
    F30 daily driver

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