Bad Prep or Bad Paint
 

Can anyone tell me what's causing the paint to do this? I wiped the valley pan down with Brake Cleaner before painting, was that a bad move? Should I prime it before painting? Thanks.

Think I answered my own question... The primer did the trick. Thanks.

You always want to follow up your preferred degreaser (brake clean, in this case) with a good wax & grease remover (personally, I always preferred R-M 900 Pre-Kleano to Ditzler or DuPont, but YMMV). Then tack cloth, prime (always; at least one coat), and then color (at least two coats, depending upon what you're painting, the color, the depth, 1-stage or multiple, etc.).

For high temp applications, try the Eastwood High-Temp Engine Primer. (I knew a guy at the shop which did the original work on my '63 Bonneville in '76 and '77, and later, in '86 who used epoxy primer on his '67 GTO engine. Epoxy primer is nasty stuff, and at the time required a forced air respirator. I have no idea if such precautions are needed now, but I've never used the stuff.)

In short, the rule of thumb is always that painting is 90% preparation and 10% application. If the surface isn't ready to accept the paint, that's a preparation issue (unless you've got issues with your water separator at the compressor or some other application failure - but water or oil in the paint is easy to spot when you throw it).

Anyway, you figured it out.

Thanks Lewis. Appreciate the valuable information.

Primer will do the same if surface is still contaminated and oily. Some react a little better if they dissolve into it if contain similar chemicals, only hiding an issue that is still there.

Those are fish-eyes, usually caused by surface contamination. FWIW, I don't use brake cleaner on a surface I plan to paint, only to clean brakes. And I don't paint brakes, so I don't know if they would fish-eye..

Make your first coat super light.

Yep. It's all good now. Thanks All.

Yep. I went very light and applied several coats after each dried. Thanks.