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Do I need to prime engine parts before I paint them?

8K views 16 replies 13 participants last post by  NH69Z28RS 
#1 ·
Another idiot question but I'm just not sure and I don't want to do more work than I need to do. But I do want to do it right. I searched around but I never seem to find the answers I'm looking for.

So, for my engine bay parts like the air cleaner, plug wire stand-offs, ignition coil, etc. do I need to prime them (after taking them to bare metal) before I spray them with the correct colors?
 
#2 ·
I think it depends what your top coat is. If you using spray bombs it may have a primer built in. If your spending the money on a pro refinishing product you'll need to follow that system.
 
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#4 ·
I'm sure a true paint guy would prime first....but I have done a lot of engine parts and have never used primer and never had a problem...Whenever I did want a really good finish on some parts, I would simply get it powder-coated....but you can get a really good finsih out of a rattle can...I personnally like the Krylon brand.
 
#6 ·
I'm sure it will work ok without primer, but I spend a lot of time prepping and or blasting my parts, and if you have a run or reaction you have to start all over, so I normally prime any part not requiring high temp paint.

If you have access to a blast cabinet to prep your own parts,powder coat is real cheap then. I had many small parts and brackets powdercoated.
 
#8 ·
You can always call the paint manufacturer's tech line and ask for their recommended procedure. They get these questions all the time and don't want you to end up with a bad result since bad news travels fast so they should have the best method.
 
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#10 ·
While not an answer to your primer question, you might look into Eastwood's new 2K Aerospray High Temp Engine Paint (Chevy Orange is #14927Z). I've never used it, but it sounds pretty interesting. The aerosol can contains 2 separate chambers that are mixed when sprayed and catalyzed accordingly. The video suggests one chamber is first ruptured and the paint mixed giving it a finite pot life so any remaining paint can't be put on the shelf for later use, but I'm not sure about that. This would be like spraying an epoxy type paint I guess. Might be more durable than a conventional paint and worth checking out. They have some videos that discuss engine painting including a special cleaner, a 2K primer and the catalyzed 2K paint. They recommend a primer first. Unless you're in a huge hurry, you could buy a can of the 2K and try it along with a conventional engine paint side by side on the same piece of scrap metal. Let the paints fully cure and test their respective mechanical resistance to chipping, abraision, etc. Once mixed, any paint remaining in the can of 2K will be trash so you'd end up wasting a can of the 2K running this test, but that's what I'd probably do. I would only want to do that job once when the engine is out of the car.
 
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#13 ·
#14 ·
The engine plant didn't prime before painting. Why do you guys make it so hard on yourselves? Seriously, what do you think you're engine is going to see during normal operation? Any good quality engine enamel will go on fine without priming as long as the parts are clean and look good for years. VHT engine paint in rattle cans does an excellent job.
 
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#15 ·
I went with Seymour EN-48. No primer, but I cleaned the block real well. This is how it came out. Like was mentioned, I pretty much fogged the first couple of coats and even hit it with a propane torch to cure it a little more between coats.





 
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#16 ·
After the engine install I like to touch up things that get scratched by spraying a little in the lid of the rattle can and buy a decent touch up brush so you don't have to worry about overspray. Just be careful when you try to get the spray into the lid I usually cover it with a rag and where gloves, it splatters easy.
 
#17 ·
Having the parts clean is the most important thing as others have mentioned. Plus due to the heat from the engine, the paint will get baked from use which only makes it work out better.
 
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