How To Prep An Engine For Paint

Engine heat wreaks havoc on pigment, even the paint on the hood tin fade from the heavy dose of radiant heat from the hot engine below. How well practise you think that rattle-can pigment job is going to last? We have sprayed engines with spray cans, fifty-fifty the high-heat versions, merely to come across cracks, flakes and fading in only a few weeks of utilise. Have a await at any high-buck build and the engines are painted up to match, but they don't fade, crack or flake, how practice they do it? How to pigment an engine so that it lasts is all in the method. Rather than take a chance with a rattle tin can, we did some research to observe out what the best method is for a long-lasting engine paint task. After spending some fourth dimension talking with diverse restoration and custom shops, we had our solution.

Painting an engine can be done either before assembly or after, it really does not matter. Our 302 block had been machined and is ready to assemble, so we just painted it up before assembly. The engine was wiped clean with paint thinner and then wax and grease remover. — Painting an engine tin be done either before assembly or after, it really does not matter. Our 302 cake had been machined and is gear up to assemble, so we but painted information technology up before assembly. The engine was wiped clean with pigment thinner so wax and grease remover.

Since the motor is not assembled yet and still has the old paint on it, some serious cleaning was needed. The plan is to soda blast the block. Baking soda is great for engine cleaning and it is ok to get it inside the engine, but keeping it out is pretty easy, so we taped up the engine. First, a couple of layers of masking tape for the base. — Since the engine is not assembled withal and yet has the one-time pigment on information technology, some serious cleaning was needed. The plan is to soda boom the block. Baking soda is great for engine cleaning and it is ok to go it inside the engine, but keeping it out is pretty easy, so we taped up the engine. First, a couple of layers of masking record for the base.

Then the main cavity was covered up with newspaper, we used two layers here. The piston bores and lifter valley were taped up in the same manner. — Then the main cavity was covered up with newspaper, nosotros used two layers hither. The piston bores and lifter valley were taped up in the same mode.

There are ii problems with painting an engine – adhesion and heat. The first is relatively unproblematic to solve with hot-tanking, scrubbing or in our case, soda diggings. We spent a couple of hours tediously taping up the engine for soda blasting. In the finish, the record didn't go along the soda out of the block and co-ordinate to several soda-nail resource, is not fifty-fifty a problem. Baking soda readily absorbs into oil and water, and the hardness of the textile is beneath that of even the softest begetting surfaces, so taping earlier diggings turned out to be a large unnecessary hassle. If you are painting an assembled engine, the all-time bet for the prep piece of work is hot soapy water and lots of elbow-grease.

We took the engine outside and set up the blaster. For this type of cleaning, all you want is soda. The blaster uses a mechanical dead-man valve to shut off the flow of media. While great for small projects and value, the heavy spring on the valve leaves your hand worn out. For small parts, like this engine, it worked great. Note that all of the holes in the engine were taped up. — We took the engine outside and prepare up the blaster. For this blazon of cleaning, all you desire is soda. The blaster uses a mechanical dead-man valve to shut off the flow of media. While dandy for modest projects and value, the heavy spring on the valve leaves your hand worn out. For minor parts, like this engine, it worked great. Annotation that all of the holes in the engine were taped up.

Because soda is very soft, tough spots like inside corners, pitted areas and edges are more difficult to blast, requiring more effort on your part. Baking soda has a hardness of 2.5 on the Mohs scale, while the hardness of engine bearings is around 6, so even residual soda left in the motor will simply be absorbed into the oil (or water) until you change it. No harm, no foul. — Because soda is very soft, tough spots similar inside corners, pitted areas and edges are more difficult to blast, requiring more endeavor on your part. Baking soda has a hardness of 2.5 on the Mohs scale, while the hardness of engine bearings is around vi, so even residual soda left in the engine will only be absorbed into the oil (or water) until you lot change information technology. No damage, no foul.

The heat issue is the biggest problem. The enemy of paint is rut. We take all seen how paint bubbles upwards when oestrus (like from a heat gun) is applied. These are the same mechanics at piece of work on a painted engine. In the case of rattle-can paints, no amount of oestrus resistance additives can combat cylinder head heat. The problem is that rattle tin pigment is besides thick. The paint used in these cans is non-catalyzed, which ways it has to rely on special solvents to cure. If you have ever sprayed a cold rattle-can, you know that it takes two or three times every bit long for it to cure. This is because the solvents must vaporize before the paint cures. Thick paint reduces heat transfer, which allows the rut to build on the surface of the engine, instead of wicking to the air; only like spreading butter on a burned finger, it merely traps the rut.

11. Soda blasting leaves a residue on the metal, which must be neutralized. Skipping this step would be akin to soaking the engine is oil before painting, the paint will just fall off. We used a vinegar/water wash to clean the prepped engine. You know it is working by the bubbles. Then we installed the heads without gaskets. These are only hand tight, no torque. — Soda blasting leaves a residue on the metal, which must be neutralized. Skipping this pace would be akin to soaking the engine is oil before painting, the pigment will just fall off. We used a vinegar/water launder to clean the prepped engine. You know it is working past the bubbling. And so we installed the heads without gaskets. These are only hand tight, no torque.

Next, the engine was taped up so that the only areas we wanted painted were exposed. This means gasket surfaces and hose areas get taped. — Next, the engine was taped up then that the only areas we wanted painted were exposed. This means gasket surfaces and hose areas get taped.

Traditional automotive paint, the kind that is sprayed with a pigment gun, either single-phase or base of operations\clear, is cured with goad. While these paints all the same utilize solvents, the solvents dissipate much faster than rattle-can paint, and accept an active ingredient that actually cures the paint. In base of operations\clear formulas, the base of operations coat does not have a goad, it is instead thinned using reducer depending on the temperatures of the temper at the time of spraying. The clear coat, along with single-stage paints, are catalyzed with hardener. The hardener cures the pigment so that it is stable. These paints are thinner and have more than fifty-fifty coverage than rattle-tin can paints. This works to our advantage, as the thinner the paint, the improve the rut transfer.

Using a measuring cup, we mixed only enough Napa base color to fill one cup for our gun. The base is a 1:1 mix, with these cups, it is hard to go wrong. A smaller cup would have been nice. — Using a measuring cup, we mixed only plenty NAPA base color to fill one cup for our gun. The base is a 1:1 mix, with these cups, information technology is hard to go incorrect. A smaller cup would accept been nice.

But what about primer? All automotive paints require primer to get adhesion right? Admittedly, if you are talking about sheetmetal. It is truthful that you would not want to spray a car without primer beginning. For one the paint would be splotchy from variations in the torso piece of work, but also the paint has a hard time sticking to smoothen sheet metal. An engine uses more porous materials, similar cast aluminum and bandage fe. The paint won't have a trouble sticking to these materials, as long as it is make clean. The chief problem with primer, fifty-fifty bones etching primer, is that it is thicker than the pigment itself. Call up, the thought is to reduce the thickness of the paint. Then when painting an engine, leave the primer out.

The gun used for this job is a Devilbiss detail gun. The smaller tip provides a smaller fan, so you don't get as much overspray. This is the perfect gun for this job. A big gun will work too. Spraying paint on an engine requires a light touch. You want just enough paint to cover the surface without being splotchy. — The gun used for this job is a detail gun. The smaller tip provides a smaller fan, so you don't become as much overspray. This is the perfect gun for this job. A big gun will work too. Spraying paint on an engine requires a light touch. Yous want just enough paint to comprehend the surface without being splotchy.

The engine was rotated to give access for the underside. There are a lot of nooks and crannies, these need to be reached. You could easily leave the engine like this, though the paint would require mixing with hardener before painting. It looks good, but not quite ready. — The engine was rotated to requite access for the underside. There are a lot of nooks and crannies, these need to be reached. Yous could hands go out the engine like this, though the paint would crave mixing with hardener before painting. It looks proficient, but non quite ready.

24. The silver metalflake was sprayed through the gun with a large 2.0 tip. We had to be careful not to put too much in one area. Once we had the metal flake on the motor, we sprayed the last coat of clear. Again, this was light but solid coat, covering all surfaces. — The silver metalflake was sprayed through the gun with a big two.0 tip. We had to exist conscientious not to put too much in one surface area. Once we had the metal flake on the engine, we sprayed the last coat of clear. Again, this was light but solid glaze, roofing all surfaces.

For our pocket-sized block Ford (a 347 cid stroker really), the thought was to paint information technology crimson and add together a affect of metallic flake. While the metal flake might not be suited for a resto, the process is the same. We used a base\clear NAPA Martin Senour paint, and sprayed the engine in the shop. Proceed in heed that spraying this kind of pigment generates a lot of overspray, much more than a rattle-can, and then if you don't desire it tinted engine color, encompass information technology. If you accept the space you can create a temporary paint booth by hanging plastic sheeting from the garage ceiling to go on things contained. You also need a respirator with charcoal packs. You actually practice not want to exist breathing the vapors of this stuff. We spent about ii days prepping and spraying our engine.

Once the paint had cured, it was demasked and then the engine was assembled. Here is the finished product. — Once the paint had cured, information technology was demasked and and so the engine was assembled. Here is the finished product.

Cheque out all the paint & body products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more than information on how to pigment an engine, chat with a knowledgeable expert at your local NAPA Machine PARTS store.

Jefferson Bryant View All

A life-long gearhead, Jefferson Bryant spends more time in the shop than anywhere else. His career began in the car audio industry equally a store manager, eventually working his way into a position at Rockford Fosgate as a production designer. In 2003, he began writing tech articles for magazines, and has been working every bit an automotive journalist e'er since. His piece of work has been featured in Car Craft, Hot Rod, Rod & Custom, Truckin', Mopar Muscle, and many more than. Jefferson has also written 4 books and produced countless videos. Jefferson operates Scarlet Dirt Rodz, his personal garage studio, where all of his magazine articles and tech videos are produced.