How to Clean a Vehicle's Engine
Many car owners never bother to deal with the dirt under the hood. There are practical reasons for removing a gross accumulation of grease, oil, fuel, and dirt from under the hood and for making an effort to keep things under control from then on.
Most engines are made of metal and depend on rubber hoses, gaskets, and wiring if they’re to work properly. Because all the aforementioned baddies can seriously deteriorate nonmetal parts and wiring, keep the under-the-hood area as clean as possible. If it’s beginning to look grubby, get a rag and wipe off as much of the dirt and grease as you can without removing or moving hoses and wiring.
Never use a hose to wash under the hood — the water can ruin the electronics. Have your engine cleaned professionally if it’s too dirty to wipe clean yourself. When the job is done, you should be able to keep it in good condition by simply wiping off the area every now and then.
If you’re planning to sell your vehicle, think twice about having the area under the hood cleaned. Although cleaning certainly spiffs it up, potential buyers may assume that it was done to obliterate signs of unsuccessful surgery on the engine.
Whenever you clean under the hood, make sure that you clean the blow-by on the inner surface of the hood, too, and that you remove the mud and dirt that have accumulated on the inner walls of the car’s body and near the wheel wells.
If you find that oil accumulates very quickly on your engine, first check the PCV valve to see whether it’s plugged up. This little gadget is responsible for rerouting the exhaust fumes from the crankcase back to the engine, where they’re burned again and then released through the exhaust system. If the valve gets plugged, pressure can build up in the crankcase and create oil leaks around the engine. A PCV valve can be checked and replaced very easily.
Oil also may seep from under the valve cover gasket if the cover needs to be torqued down properly or the gasket needs to be replaced. If this seems to be your problem, check with a mechanic.