Moparts

i have the worst luck repainting things...

Posted By: mickm

i have the worst luck repainting things... - 04/21/14 05:13 AM

i went to repaint the oil pan, which i had done with self-etching primer and mopar rattle can paint. i used some paint stripper, and it took the paint off nicely, but didn't take the primer all the way off, and left a not smooth surface. so i hit it with another round of stripper, and blasted it with the hose, hooked up to hot water.

it looked good, and seemed to take a lot of the primer off, but not all the way to metal. so i wire brushed it, got it nice and smooth, went over it all with scotchbrite, and then washed it with tide and a scothbrite type sponge. came out really nice. lots of traces of the primer, but smooth to the touch yet roughed up slightly from the wire brush.

painted it again, and it looks like crap. raised areas all over the place, i'm assuming corresponding to where the remains of the primer was.

so what now? i figured it was ok to leave that last bit of primer on there, but apparently not.

i don't want to media blast it, as that could leave little particles tucked in the baffles inside, but i assume i have to get this all the way to bare metal.

how do i clean this thing up and get it ready to paint again?
Posted By: Suregrip391

Re: i have the worst luck repainting things... - 04/21/14 12:09 PM

Maybe a machine shop? Hot Tank it?
Posted By: Challenger 1

Re: i have the worst luck repainting things... - 04/21/14 04:28 PM

Don't use primer only engine paint. That's the problem. Wet sand it with water, start with courser paper and finish with 320 grit.

You don't need primer, it's not hi temp rated. I have painted at least 30 motors and never used primer, the motor get's too hot for primer.
Posted By: mickm

Re: i have the worst luck repainting things... - 04/21/14 06:07 PM

Quote:

Don't use primer only engine paint. That's the problem. Wet sand it with water, start with courser paper and finish with 320 grit.

You don't need primer, it's not hi temp rated. I have painted at least 30 motors and never used primer, the motor get's too hot for primer.



it looks that way. it's amazing how well the primer stuck to the metal, and how poorly the paint stuck to the primer.

time to strip it again and get it to bare metal...
Posted By: RSNOMO

Re: i have the worst luck repainting things... - 04/21/14 06:50 PM

Get it stripped, and properly prepped...

Is primer needed???

While not OEM, I'm of the belief that primer exists for a reason...

Would you put color over bare sheet metal???

I prepped, primed, and put color on an engine that's gone 20+ years..

It's holding up real well...
Posted By: His and Her 69's

Re: i have the worst luck repainting things... - 04/22/14 06:47 AM

We have blasted the pans before and what you do is seal off the inside of the pan. I use cardboard and the wide green painters tape and I make sure it is sealed off so no sand gets in. rinse it before you take off the tape etc. After the outside is clean then do the inside with brake clean or something, then a Good blow dry.
Paint or primer away.
David
Posted By: mickm

Re: i have the worst luck repainting things... - 04/22/14 07:52 AM

Quote:

We have blasted the pans before and what you do is seal off the inside of the pan. I use cardboard and the wide green painters tape and I make sure it is sealed off so no sand gets in. rinse it before you take off the tape etc. After the outside is clean then do the inside with brake clean or something, then a Good blow dry.
Paint or primer away.
David



i was thinking of that, sealing it off really well.

i'll give that a shot. easier than trying to get all that damn primer off by hand!

thanks!
Posted By: Stanton

Re: i have the worst luck repainting things... - 04/22/14 03:40 PM

IF paint stripper didn't take the primer off, a hot tank probably won't either. Sandblasting ... depending on the grit you could end up with a coarse finish that doesn't give you a final smooth finish once painted.

I'd hit it again with the paint stripper and what it doesn't take off I'd hit again with the stripper and a scraper and keep at it till its got it all.
Posted By: mickm

Re: i have the worst luck repainting things... - 04/23/14 06:28 AM

Quote:

Get it stripped, and properly prepped...

Is primer needed???

While not OEM, I'm of the belief that primer exists for a reason...

Would you put color over bare sheet metal???

I prepped, primed, and put color on an engine that's gone 20+ years..

It's holding up real well...



ok, so here's another question: what does properly prepped mean?
Posted By: Stanton

Re: i have the worst luck repainting things... - 04/23/14 01:52 PM

stripped, wiped with oil & wax remover, wipe with tack cloth, prime, paint
Posted By: mickm

Re: i have the worst luck repainting things... - 04/23/14 05:01 PM

Quote:

stripped, wiped with oil & wax remover, wipe with tack cloth, prime, paint



what primer do you use? when i painted the engine i used self-etching primer. the primer stuck like glue to the metal, the paint didn't stick well to the primer at all.
Posted By: RSNOMO

Re: i have the worst luck repainting things... - 04/23/14 05:59 PM

The primer I used was specifically for an automotive engine application...

The block was degreased, coupla' spots I didn't like were hit with Rust Mort...

Coupla' primer coats, then color...

The primer grabbed the color, and made coverage much easier than trying to get flow on a 'bare' surface...

All rattle-can...
Posted By: mickm

Re: i have the worst luck repainting things... - 04/24/14 12:37 AM

local hardware store has rust-oleum engine primer. going to give that a shot...
Posted By: Kern Dog

Re: i have the worst luck repainting things... - 04/26/14 10:40 AM

I use a wire wheel on a 4" DeWalt grinder, then always spray SEM Self Etching primer on all tin. Cast iron? Nah....But always use primer on the tin.
Posted By: GY3

Re: i have the worst luck repainting things... - 04/26/14 06:05 PM

Quote:

I use a wire wheel on a 4" DeWalt grinder, then always spray SEM Self Etching primer on all tin. Cast iron? Nah....But always use primer on the tin.



Yep, braided wire cup wheel will make short work of it on an angle grinder.
Posted By: mickm

Re: i have the worst luck repainting things... - 04/27/14 06:14 PM

Quote:

I use a wire wheel on a 4" DeWalt grinder, then always spray SEM Self Etching primer on all tin. Cast iron? Nah....But always use primer on the tin.



that's what i used as well. primer stuck to the metal like glue, paint stuck to the primer like, well, not glue. chipped and knocked off very easily.

of course it is mopar paint. i've had good luck with it in the past, but i know many people don't like it. i think this time i'm just going to rough the surface with 320 grit, and go with straight paint. can't be any worse than it was...

well, i hope not!
Posted By: BarrsRestoration

Re: i have the worst luck repainting things... - 04/28/14 06:23 PM

Even though some of the primer remained, it was still affected by the chemical stripper. Any time that you use a chemical stripper, you have to remove every single layer and every trace of paint, primer and filler. ANYTHING touched by stripper that remains will cause adhesion problems when you re-coat it.
We scrape, then scrub with soapy water and a scotch-brite pad. Rinse, completely dry, then blast or sand any remaining material off.
Posted By: mickm

Re: i have the worst luck repainting things... - 04/28/14 07:39 PM

Quote:

Even though some of the primer remained, it was still affected by the chemical stripper. Any time that you use a chemical stripper, you have to remove every single layer and every trace of paint, primer and filler. ANYTHING touched by stripper that remains will cause adhesion problems when you re-coat it.
We scrape, then scrub with soapy water and a scotch-brite pad. Rinse, completely dry, then blast or sand any remaining material off.



yes, i learned that. stripped it completely, washed it with a degreaser, then hot soapy water. rinse, sand with 320 grit, and painted and nice and shiny!
© 2024 Moparts Forums