Why should you clean the engine compartment? Rust prevention, early oil/fluid leak detection, early belt wear detection and cosmetics are among the prime reasons. (There is a rumor that certain series of German mid/rear engine cars have a factory designed engine oil leakage feature to assist in rust prevention for the non-galvanized rear quarter panels and trunk areas.)
To soften the grease and grunge collected on your engine compartment, start the engine, let it warm up for a few minutes and shut it off. The proper cleaning temperature of the engine is warm but not hot. If you can just hold your hand to the engine without burning it, then it is warm enough to clean. As the engine cools to proper temperature, use the time to cover the few openings on the motor that dislike ingesting water. The air intake/air filter, the distributor, the coil and the oil dipstick/breather are among the few sensitive areas.
Use plastic Baggies and rubber bands to cover the air intake/air filter(s) and the distributor/coil. Place a double layer of Baggies over the air intake and secure with a couple of rubber bands. Use a pair of two-gallon size Baggies to cover the distributor and plug wires around the distributor cap. This may be difficult to seal, but the idea is to prevent significant amounts of water possibly shorting out the distributor. If the cap is in good condition, it will be waterproof, so this is only a preventative measure. The coil is also waterproof, so Baggies are again a preventative measure. Check the tightness of the oil filler cap, the power steering filler cap, windshield washer fluid cap, oil dip stick, battery filler caps and all other engine compartment opening caps and secure baggies over them with rubber bands.
Now that your engine is warm and sealed, spray the entire engine/engine compartment with a quality, non-petroleum based degreaser. Try to start from the bottom and work up. This way you don’t have the degreaser dropping on your face as you clean the underside areas. My favorite citrus based engine cleaner is P21S Total Auto Wash. I find that this citrus product will clean thoroughly and not harm the paint or finish of the aluminum components and are biodegradable. One note of caution, all degreasers will remove your nice coat of wax. If you get the engine cleaner on the waxed areas, plan on rewaxing. Allow the degreaser about 3-5 minutes to work and then use a 100% cotton towel or a SOFT brush to GENTLY agitate the heavily soiled areas. Respray and rebrush any areas that need additional cleaning. Once the entire engine/engine compartment has been cleaned, rinse thoroughly with water. There is a debate as to the optimum force of spray to rinse the degreaser. Some say a gentle spray is all that is necessary, while others advocate the use of a high-pressure spray. Use your common sense. The stronger the spray, the more likely you will get water in sensitive parts. If all areas are properly protected, you should have no problems with a stronger spray. If any areas need additional cleaning, repeat as necessary.
Once the engine/engine compartment is clean, immediately remove all of your plastic baggies/rubber bands. Dry any puddles and aluminum parts with a soft, 100% cotton towel. Use paper towels to thoroughly dry the battery (if it is in the engine compartment). Start the engine and allow it to warm up. This will dry the rest of the engine and evaporate any moisture that may have collected in sensitive components.
I am not a fan of steam cleaning. I have found that the high pressure steam has a nasty tendency to infiltrate the electrical connections and cause havoc. The modern engine has numerous sensors that continually feed precise information to the computers. If steam penetrates these sensors and corrodes the electrical connections, electrical signals may be disrupted and cause the engine to run erratically or not at all. The amount of time it takes to disassemble, clean and reconnect all these sensors is incredible.
Once everything is dry and has completely cooled, you may wish to apply a coating of rubber protectant to the rubber hoses, rubber, plastic shields and rubber gaskets. One Grand Exterior Rubber & Vinyl Treatment and Meguiars #40 Vinyl/Rubber Treatment both work extremely well. I do not recommend treating the underside of the rubber belts, as this makes them reluctant to turn their respective pulleys, with somewhat interesting results. (This is somewhat like waxing brake pads.)
The painted areas of your engine compartment (not the engine) should be waxed. If the uncoated aluminum areas are dull or have whitish corrosion, a mild metal polish will help restore the finish. My favorite is P21S Multi Surface Finish Restorer Polish. Use a soft, 100% cotton flannel cloth and work a small amount into the surface and then buff off with another 100% cotton flannel cloth. Check the battery terminals, to insure that they are clean. If not, disconnect the cables and clean both the cable terminals and battery posts with a wire brush. Reconnect the terminals and retighten.
Lastly, check all fluid levels, remove any stray Baggies and you are finished!
If you have any questions or if you need any further information, please feel free to contact us.