How to Prep Your Engine Compartment for Paint
I thought I’d talk a little about the restoration of your engine compartment, since it is one of the problem areas in a lot of car restoration projects, the first thing that you usually notice, it’s the the engine compartment so it’s full of grease, and of course an engine, so the first thing that you need to do is pull the engine out of the car, it’s a lot easier to pull the transmission with the engine, and pull them as a single unit.
You’ll notice once you do this, that it’s a lot greasier then you thought, but now you can at least get to it to clean it up, first I’d take a steam cleaner to it, and see how much of the grease and years of dirt an road grime that will take off, and don’t be thinking that this will be fast, once you can see that the steam cleaner is not getting any more of the grime out of the engine compartment, go ahead and put some degreaser on the areas that are still bad, and give the degreaser about 30 minutes to loosen up the grime.
After that, you guessed it, it’s back to steam cleaning again, what this doesn’t get, you’ll be scraping off, so be prepared to get dirty, now there is always dirt and road grime that the steam cleaner will not remove, unless the person who owned the car before you was vary in love with his car, and cleaned the engine compartment regularly, this will without a doubt make a big difference in what you have to do to get it clean, once your through scarping all of the grime off, you can break out that steam cleaner again, and give it one last shot.
After that you’ll need to take some acetone, or something like it and do your final clean up of the engine compartment, you’ll know it’s clean when you don’t see any more black on you cleaning rags, once you get to this point, it’s time to determine what needs to be fixed in the engine compartment before you can start prepping it for paint, look around for any rust, or dents that need to be fixed, you’ll know the rust by how it looks, rust will show up as bubbles in the paint, pits in the paint, or just big ugly holes, now if you see some bubbles in the paint in you engines compartment, first scrape the top of them off, and then check to see how bad the rust is by “Lightly” tapping the rusted area with a pick hammer, if the hammer puts a hole in you engine compartment, you’ll know that the rust was to an advanced stage, and you’ll need to repair it before you can go any farther on your project.
To repair that rust hole, or any rust hole, you’ll need to determine how large the effected area is, and I suggest that you draw a line around the area, after you do that, you’ll need to be sure that you have a die grinder with a cutting blade installed on it, what you’ll do now is plug your die grinder in to the air chuck, and then follow the line that you drew around the rusted area, and do yourself a favor, and cut a little at a time, make one pass over the line that you drew, just to give yourself a guide for the die grinder, all you’ll be doing here is passing your die grinder over the guide lines that you created until the rusted area is cut out of the engine compartment, now you should de-bur the area that you cut out.
After you get the area all cleaned up, take some two inch masking tape and put it across the hole, and then take a sharpie and follow the outline of the hole, pull it off of the hole and put it on the piece of sheet metal that your going to use to fix the hole in your engine compartment, take your die grinder and work around the line until you’ve cut out a piece of metal in the shape of the rust hole in your engine compartment, by now you can see where I’m going with this whole idea, OK now take that piece of metal and fit it in the hole in your engine compartment, now that you’ve got it all fit in place, it’s time to find a way to make it stay there while you weld it in, I usually use Visegrips to do this, but how you hold it in place is all up to you, you will want to make sure that it sits in place as level as possible, it will be a lot less work to finish the job if you do this, when you begin to weld the plate in place, your not going to run a solid bead around it all at one time, it will be a solid bead in the end, but work from one side to the other, and do about a one inch weld at a time, otherwise you’ll warp the metal, and cause a lot more work for yourself , so when you start, you’ll have a one inch inch bead on all four sides holding the metal in place.
Once you have made a solid weld bead around the entire patch panel, you can once again get your die grinder out, and this time put a grinding blade on it, and grind the wed bead flat, once the is done, take a dual action sander, or “DA” and put some 180 grit sand paper on it, and smooth out the rough areas in the paint, that the die grinder made, and the rough up the bare area again with some 80 grit paper, after that is done get out your mixing board, and metal glaze and mix up some metal glaze and spread it over the patched area, and then sand it with 80 grit paper on a hand block, and if needed, repeat this process again until the area is smooth and just a little high, and then load that block with 180 grit paper and level out the high spot.
Now you’ll need to primer the area that you just repaired, I would use a urethane primer for this, the brand is up to you, depending on the brand, mixing instructions will change, so be sure to ask you paint supply house to explain to you how to mix the brand that you choose, the one thing that doesn’t change in the flash time between coats, this should be about 15-20 minutes, and you should lay at least 3-4 medium wet coats of primer on the repaired area, after you get this done, you’ll want to spray a guide coat on the primer, so when you begin to sand the primer, you can see that high or low spots in your repair work, and usually you’ll have one, the other, or both, now that you have your guide coat on the primer, and the primer has had time to dry, I would give it no less then four hours to dry, but even better yet 12-24 hours of dry time. Now that it’s dry, load that hand block with 180 grit paper and sand the guide coat off, you’ll notice that their are high or low spots in your work, you’ll need to determine if primer will fill it, or if you need more glaze to be applied to your work area.
For now let’s say that your work was smooth and right the first time, so now your done fixing the rusted area, you’ll need to get a a bucket and put some warm water in it, and this will be your wet sanding bucket, and a water spray bottle is nice to have also, now you’ll need 600 grit wet sand paper to sand you engine compartment, this is of course if the rest of the engine compartment is free of dent, dings, and nicks in the paint, once you know that it is you can sand the entire engine compartment with wet 600 grit sand paper, and the areas that you can’t reach wit that, you can use a gray scotch brite pad, once the entire engine compartment is dull, you can then use a prep cleaning solvent to clean it up, and make sure that you get all of the residue from wet sanding out of the engine compartment.
Your now ready to spay the paint, after you mask the rest of the car off, so you don’t get paint where you don’t want it.
Well cover that painting of the engine compartment in the next article.