If you are someone that has just completed an overall paint job or if you are detailing your engine compartment it is important to take precautions when painting your engine, firewall and other components.
The main thing to remember when painting in tight places is that you should not rely on your full size gun with a large pattern. Even if you are painting with your engine removed but with your other components still in place you do not need all of the power that a full sized gun will provide.
If you are painting with your engine and (if transverse) transmission in place then a large gun will make it impossible to get into tight places.
For this reason you will want to invest in a detail / touchup gun for the larger areas and a air brush for the tighter spots.
Believe me between a touchup gun and a air brush you can make a complete change over of color without the need to pull your engine and most of its components if you are careful and take time to properly mask everything else.
You may think that pulling everything you can get a wrench on is best but the time to do it is not the only problem. If you misalign parts that are already installed replacing other parts will be difficult and require going back and fixing your mistake. If you break something while removing and replacing parts just so you can paint you will be pretty ticked off and you have just increased the cost of your restoration.
Picking Paint Type and Color for your Engine
If you are restoring an original color then your selection has already been made for you.
Manufacturers will provide a list of official engine colors for each model year. If you happen to paint your engine the wrong color you will definitely lose points if you are showing your vehicle but you may also lose customers if you are selling your vehicle.
Engine Enamel in a spray can can provide a quality coating that resists heat. It also comes in a variety of colors for matching or changing the look of your engine.
Crackle paint is available for valve covers and other components to restore the texture that is found on OEM surfaces. I would suggest that you practice before committing to your actual part if you are using a texture paint.
Masking the engine compartment
Once you have cleaned the engine compartment and dried it thoroughly you can begin masking all of the items that you don’t want paint on.
Painter’s tape works well to lay down a hard edge or to mask your bolt heads. For larger areas you can use kitchen plastic wrap or paper. You do not want to cover large areas with tape alone because you risk pulling up tape and masking tape can bleed color so use a barrier like plastic wrap or drop cloth or even newspaper in a pinch.
Although you may not want to remove all of your components I would suggest that you remove your accessory belts and spark plug wires. You should also remove your cold air intake tube and possibly the box if you need to touch-up under or around the box.
Radiator hoses can be masked with plastic wrap… you are realizing i seem to love plastic wrap.. its because it is cheap, does the job and doesn’t always require tape since it can stick to its self.
Make sure you wrap your axels and CV Joint Boots.
Final Cleanup before Painting
Final cleanup should remove any remaining oils so that your paint will adhere properly. There are a number of different prep solvents that you can purchase at your paint store or you can use a chemical cleaner that will not leave a residue.
Break cleaner is specifically made to not leave a residue and it is good to use on bare metal surfaces that will receive paint. If you use it on painted surfaces you must be careful to test an area to make sure that it will not lift the paint.
Ammonia based cleaners are also good however if there is a sudsing agent you must wipe it down with water.
After the area is free of oils and dirt you want to make sure that it is dry.
An air duster attachment for your air compressor will work well but make sure you don’t lift the masking tape or plastic.
Painting the Engine
Your first coat should not be your final coat when applying engine enamel.
The first coat should be a Tack Coat.. this is where you spray a 1/4 full coat or very heavy dusting of paint just to make the surface sticky.
The tack coat will act as a primer in some ways too by allowing your second coat which is a full coat to adhear to it rather then the metal or surface you are painting.
Tack coats will also reveal problems with oils. If you have oil on the surface then paint will not stick. It is better to find out now then later.
Finish your work with at least 2 full coats over the entire surface. You want to start at one end and work your way completely around then allow the paint to flash dry for about 20 minutes then apply your final coat.
If you think you need a third coat then you should allow the paint to dry at least 20 more minutes but better to allow it to dry until you can touch a masking tape area with your finger and it is not tacky.
You can also allow the paint to dry overnight or for a few days and apply an additional coat if you dust it first.
Dealing with Runs in Metallics
Unlike urethane paint which is forced dry and able to be sanded if you have a run in metallic paint from a spray can you can not use heat to dry it.
Your best bet is to allow it to cure for at least a week before attempting a repair.
Final Note
Painting your engine should not be like painting a work of art. You want to get it done and make it look good.
If you know you will be replacing accessories then you have the option of removing them before you paint but if you will be keeping them then protect them so paint wont cause damage. You do not want to get paint into your alternator or any sensors or connectors.
Painting the face of your pulleys is fine but do not get paint on the grooved edges where the belts ride. If you do you will most likely burn and glaze the surface of your belts and they will need to be replaced.
When using chemical solvents around your engine you should make sure that they are O2 Sensor friendly .. there are two types of brake cleaner that you can purchase one of them is specifically O2 sensor friendly .. buy it.. non chlorinated.
Pulling your engine components should be your last choice but valve covers normally come out better if you remove them ..