Painting engine compartment Questions?

[john108]

Painting engine compartment Questions?
Do you paint the engine compartment with the same number of primers and procedures as you do the exterior. 
I am planning a simpler approach but would appreciate your feedback.
The existing paint was not bad considering being 45 years old. 
I cleaned the surfaces very well then roughened it with a wire wheel in a drill.  Cleaned again then gave it a coat of rustoleum primer for rusty surfaces hoping it would provide a good sealer.
I don't know if that was a good approach, or not, and now wondering if another coat of something should be applied before the top coats?
Please offer your suggestions.
Thank you
John

[Pete in NH]

Hi,

In general, yes, you would use the same steps in painting the engine compartment as you would use on the exterior of the car. Although, you might use a single stage paint in the engine compartment while using a base/clearcoat system on the exterior, but you could use a base/clearcoat system on the engine compartment as well. Epoxy primers are a very good foundation for newer paint systems. I think you will have problems with that rustoleum primer under any modern automotive paint system and it would have been better to use an epoxy primer as a sealer over the original paint if it was really in sound condition. In general ,unless you have a lot of experience with automotive paint systems it's best to stay with one paint manufacturers system and not mix different types of products on a project. There is a lot of good information available from the paint manufacturers on their websites as to what products to use and the steps required to apply them. How you prepare and clean the surface to be primed or painted is critical to how well your new materials will adhere and paint manufactureres all have slightly different recommendations for their products.

[Troy]

I think you just shot yourself in the foot with Rustoleum primer. I'm 99% sure you can't cover that with regular automotive paint!

I'm not a painter - but I have lots of cars. I've you've got a car apart and on a rotisserie it's easy to shoot the engine bay exactly like the rest of the car. I know a couple painters though who will use a single stage paint in there because it's easier to touch up (a lot more chance of scratches and dings there than the rest of the car). The difference in gloss isn't generally noticeable because of the shade from the hood and all the curves/crevices/overlapping metal.

Troy

[sardillim]

I would check with your local auto body paint supply store.  The problem is if you have covered the surface rust with rustoleum it will likely fail if the small pits in the metal weren't thoroughly treated.  I think the auto body supply store will be able to hook you up with a better product than Rustoleim     Can you post pictures?

[john108]

OK

[sardillim]

not bad   compartment is in nice shape, surprised to only see minor pitting were the battery tray is.   I would still da it down to metal and use a different product. 

[Dino]

I found this on a website that got it from a rustoleum faq:

Q Can I use Rusty Metal Primer on clean metal?
A No. The fish oil that is in the primer needs to penetrate into rust to seal out air and moisture. If there is no rust, the oil will rise to the surface making adhesion of the finish coat difficult.


If that's true...then it means that primer will be easily removed from the smoother surfaces now, let alone after a top coat.

At this stage I think you need to just face the music and remove the primer. 

[Cooter]

I've shot gun paint right over spray bomb. Just do a test panel to be sure it won't lift.
my car was EV2, so "Chevy Orange" was perfect match in spray bomb. It can be done with rattle can and look ok.
I prefer auto paint, but in a bind, I have used bomb primer.

[Pete in NH]

Well, that's a bit a of a mess with that fish oil compound on there. I would not try to remove is mechanically by sanding as that will only drive that oil into the old paint surface and you will never get rid of it. It might be best to roll the car outdoors and remove the rustoleum primer with plenty of clean rags or wipes and lacquer thinner.It's going to be a messy, nasty job but, you really need to get that stuff off there. When you get it off , I would again wipe the whole thing down with plenty of clean wipes and lacquer thinner. Then I would wash it with a strong solution of a good grease cutting detergent like Dawn dishwashing soap. I would do that twice. You need to get all traces of that fish oil off there or you will have adhesion problems with anything you put on there. I would then pick an epoxy primer and follow that manufactureres recommendations for surface prep. It will likely involve scuffing up the old paint surface with #80 paper and wiping the surface down with both a solvent  and then water/alcohol based wax remover and degreaser.

[john108]

All good suggestions - Thank you.
I called Rustoleum Customer Service and explained everything to them. 
They informed me that the old version of Rustoleum Rusty Metal Primer did have fish oil in it.  The Current Primer Does NOT have fish oil and should not be an issue.  There suggestion was similar to Cooter's, when selecting a top coat, do a sample first.
I know that I should have used the epoxy primer but because of the complexity of the surfaces in engine compartment, I worked in small sections at a time.  Even the firewall has ripples from when it was formed.  Therefore I used the rattle can so I didn't get rust while working on other sections.  It is amazing how fast rust forms.

The following is a quote from their website:
"Rust-Oleum® Rusty Metal Primer provides the best base surface on heavily rusted metal for most brands of automotive lacquers and enamels. Provides more than two times the rust prevention of using lacquers and enamels alone."

[Dino]

All good suggestions - Thank you.
I called Rustoleum Customer Service and explained everything to them. 
They informed me that the old version of Rustoleum Rusty Metal Primer did have fish oil in it.  The Current Primer Does NOT have fish oil and should not be an issue.  There suggestion was similar to Cooter's, when selecting a top coat, do a sample first.
I know that I should have used the epoxy primer but because of the complexity of the surfaces in engine compartment, I worked in small sections at a time.  Even the firewall has ripples from when it was formed.  Therefore I used the rattle can so I didn't get rust while working on other sections.  It is amazing how fast rust forms.

The following is a quote from their website:
"Rust-Oleum® Rusty Metal Primer provides the best base surface on heavily rusted metal for most brands of automotive lacquers and enamels. Provides more than two times the rust prevention of using lacquers and enamels alone."

Sweet!  Looks like you're good to go then.  Don't forget to scuff the primer before trying topcoat.

[Cooter]

 

[hemi-hampton]

Anytime I got rust I either Sandblast it or Cut it out. LEON.

[Charger-Bodie]

Anytime I got rust I either Sandblast it or Cut it out. LEON.

I agree.

[bill440rt]

This Rustoleum primer is also going to have to withstand the heat from the engine compartment. Something to think about.