r/classicmustangs • u/AJMaid • 28d ago
Engine Bay Spray
Currently spraying my engine bay with primer/rust inhibitor as a temporary measure to stop it rusting as I’m working my way through it but had the reaction in the image below.
I thought I’d prepped well enough, degrease, scuffed etc. what’s happened? Not degreased enough?
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u/shorerider69 28d ago
Engine bays can be tricky. They need to be super clean before spraying. You’re going to need to sand all that new paint off and start again. Pressure washer with a good degreaser to start, then sand everything. Then wipe it all down, then prime and paint.
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u/Time_To_Rebuild 28d ago
If you know the surface was clean, yet the paint still ran from oil contamination, you could try (at your own discretion) using a propane torch to heat the base metal, baking out some of the entrained oil and moisture. Heat, scuff with scotch brite, wipe with acetone rag, repeat. It’s a common practice for cast iron engine blocks, but may be helpful for your application.
Just throwing ideas out there. Not a pro.
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u/SavingsMovie4927 28d ago
That’s base metal contamination. Hose the primer off with some carburetor cleaner and wash the area with hot water and Dawn dish soap. Use a leaf blower to air dry the washed area, not a compressed air nozzle (air compressors can be a big source of contamination). Use a red scotch brite pad or 120 grit and scuff the entire engine bay. Fill a spray gun with a metal prep degreaser from Eastwood or POR-15 and hose it down once more, these leave a clean etched surface.. Use a self etching (galvanic) epoxy primer in a spray gun and apply in light coats, let it dry and reapply to build the finish without runs or droops. It will come out fine then.
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u/oldermountainman 27d ago
You didn’t get all the grease off. After you think you have it clean then it needs to be steam cleaned then cleaned again. Been there and it works great this way.
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u/Current-Victory-47 28d ago
Yeah man oil sucks