Cleaning Your Car’s Engine Bay


The grease and road tar that covers most engines is both unsightly and at times dangerous. Keeping your engine bay clean is not just a matter of cosmetic appears but it is also important to keep the moving parts such as the timing and serpentine belts from becoming oily and prone to slipping. There are other benefits that are realized during repairs – clean parts are easier to locate and replace or repair. This article will run through information for keeping your car engine bay clean.

1. Why keep it clean?

Your engine is a precision instrument – every part is engineered to operate within tolerances measures in thousandths of an inch. While exterior engine grime may not be important to internal parts such as pistons and cams, it is important to the sensitive belts which must operate outside the engine.

Serpentine belts which are in poor condition can react poorly with engine grime. First, most belts are made of rubber and can be dissolved by the petroleum distillates in grime and oil. Second, these belts operate at high speed and can literally fly off their pulleys when oily.

There are indirect reasons for keeping your engine clean to keep it running longer. Leaky head gaskets, valve cover gaskets and engine seals are much easier to spot when the engine is clean. If the engine was clean a month ago and oil is appearing around these parts, odds are the gaskets need to be replaced and the oil checked – a clean engine can clue you into these events.

Finally from a less practical point of view, engines and their vehicles are investments which ought to be enjoyed. A clean engine is much more fun to show off, and it just might get the driver under the hood more often to check fluids and do maintenance.

2. How is it cleaned?

Engine grime, baked-on motor oil and road tar are not easy to remove. Luckily there are a few cleaners which are strong enough to dissolve the sticky substances and kind enough to leave wiring and gaskets intact. A mainstay of used car dealers is Mean Green, a cleaner which contains butyl cellosolve, also known as 2-butoxyethanol. Look for this ingredient when searching or a substitute cleaner if Mean Green is not available.

Please remember to keep safety first. Don’t mix cleaning chemicals, ever. Mean Green and products containing butyl cellosolve are irritating to mucous membranes and you should avoid breathing them. In reality any product strong enough to dissolve road tar will probably do a number on your body so rule of thumb: avoid breathing all cleaners.

Make absolutely certain that all fluid caps and dipsticks are firmly in place to avoid getting cleaner into the engine. Using an old spray bottle that will be used for no other purpose, spray the cleaner on all engine surfaces. Take care to saturate the most oily surfaces such as around valve covers and near the oil fill cap. If using a cleaner containing butyl cellosolve, allow the cleaner time to dissolve the dirt but do not allow it to dry completely. Then, using a garden hose or a pressure washer set on low, rinse the cleaner off as completely as possible. Mean Green will foam up and be difficult to remove in entirety, so just do the best you can. Keep in mind that cleaners containing butyl cellosolve work best on slightly warm but not hot engines. Reapply cleaner and rinse again if necessary.

For detail work, use dish soap and water to rub down stubborn areas. Do not use Mean Green with your hands unless you are wearing gloves. Remember to rinse the engine thoroughly when you are finished to avoid having cleaner and soap baked on to the hot engine block.

The next time your engine rises to operating temperature it will have a funky cleaner smell. This is normal – just allow the residue that cannot be rinsed off to dry.

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