To Primer or Not to Primer?

[ontherocks83]

I have the engine removed from my boat. One of the things I am doing while it is out is sanding it down and painting it. I have already made good progress on sanding off the paint with a dremel and an 80 grit abrasive wheel. Believe it or not, but all of the rust in the picture comes right off with the paint and the condition of the metal is in remarkably good shape. Even the top of the exhaust manifold/coolant fill on the port side of the engine cleaned up beautifully.

I have purchased a couple cans of the original bronze universal/westerbeke spray paint shown here Engine Paint for Universal Diesels, Bronze my question is; After I finish sanding and wiping down the engine, can I just spray a couple coats of this on and call it a day or is there a specific type of primer made for engine paint that I need to use first?

 

[jssailem]

I suspect that depends on the adhesive properties of the paint on bare metal and how long you want the newly painted areas to look pretty. Primers help your paint adherence to the metal.

 

[dlochner]

What does it say on the paint can?

 

[ontherocks83]

It doesn't mention primer one way or the other, just to apply several light coats.

 

[Pirate Dave]

Don't prime it. The heat from the engine will take the primer off. Put two coats of the paint on it and let it go.

 

[dmax]

I wouldn't paint bare metal without a primer, all metal paints I've dealt with require it. Worst case is you spent a little more time and money but you'll end up with a better paint job.

 

[dmax]

Pirate Dave (you posted while I was writing): I wasn't aware of that with respect to engines, so never mind what I said above.

 

[BigEasy]

I would use a primer specifically for use in high temperature applications.
Helps to inhibit corrosion and enhances adhesion.

 

[Pirate Dave]

When I did my Atomic 4, I just painted the engine paint on. No worries ten years later

 

[ontherocks83]

Thanks guys good to know! I'm just glad the engine stand and cherry picker I bought a few years ago, "just in case" are finally coming into use.

With regards to the engine stand, it is of the type where you can rotate the engine upside down once mounted on it. Once I have the oil and coolant drained out of it, is there anything else to be aware of before flipping it over to sand and paint the bottom of it?

Also I am taking the bell housing and transmission off to put the engine on the stand. Can I flip the transmission upside down while it is full of fluid or do I need to drain it first?

 

[TomY]

I painted this engine block in 2008 before installing in my boat. If I primed it, I didn't take a picture.

I'm guessing I didn't as I can't see a can of primer in the photos. For what it's worth, the paint's holding up well. Some areas that get hottest need touching up. It's salt water that you have to keep off it.

About to install the infection pump in this one after painting with Rustoleum.

 

[TomY]

On second thought,....I think I may have primed it with Rustoleum primer. I'm apt to do what it says on the can. Good luck!

 

[Barnacle Bill]

Call Marysville Marine and ask them. They are Universal suppliers.

 

[Sailor Sue]

Once the engine is out and all prepped to paint, how much time, effort, and cost is involved to prime first?

And if you don't prime before painting and the paint fails, how much time and effort is involved doing the job again?

Also, priming is a good chance to perfect your technique before the actual painting. It might show you problem areas when applying the paint.

 

[rgranger]

... is there anything else to be aware of ...

I'm sure you have thought of this but make sure you clean all of the oil residues off of all paintable surfaces or your paint won's stick. Hexane and a pile of paper towels. Followed by some acetone and more paper towels.

 

[ontherocks83]

Once the engine is out and all prepped to paint, how much time, effort, and cost is involved to prime first?

And if you don't prime before painting and the paint fails, how much time and effort is involved doing the job again?

Also, priming is a good chance to perfect your technique before the actual painting. It might show you problem areas when applying the paint.

I appreciate the sentiment, but it's not about putting in the extra work or not, but whether primer is supposed to be used on an engine or if universal/westerbeke engine paint is designed to be used without it.

 

[sailme88]

Were it my engine.... I'd take the opportunity to drop the oil pan, clean out any sludge and service the pick up filter, new gasket and paint. Good opportunity to also add a fresh coat of paint in the engine compartment..

 

[ontherocks83]

Were it my engine.... I'd take the opportunity to drop the oil pan, clean out any sludge and service the pick up filter, new gasket and paint. Good opportunity to also add a fresh coat of paint in the engine compartment..

I didn't think about dropping the oil pan. Maybe I'll borrow a borescope from work and take a look inside before pulling it off, I'm hoping it's clean and I don't have to.........but we'll see. And I agree; one of the big reasons I pulled the engine besides painting and servicing it was to also clean and paint the bilge.

 

[BigEasy]

This should work as a primer, need to use corresponding hi temp enamel for engines also.

 

[dLj]

Google NAPA know-how on how to paint an engine. Sorry, can't seem to figure out how to copy and paste the link using my phone.

No primer is the bottom line. You want as thin of a coat of paint as possible according to that source.

dj