The first step in any repair job, especially to engines, transmissions and other traditionally oily components, is to clean away all the accumulated grease and gunk. Oil and grease, baked by engine or transmission heat, can be especially challenging. Here are some options:
A hot water pressure washer is the preferred way to get to bare metal. If a steam cleaner isn’t available, I once worked with a pressure washer hooked to a large LP-fired household water heater, set to its highest heat setting. A valve allowed the choice of either unlimited well-temperature water, or 10 minutes of near-boiling water before the water heater ran out of hot water. Cold water initially cleaned off the big chunks, then a few minutes of scalding water often took care of the stubborn gunk.
Soaking greasy gunk with solvent is a slower, more labor intense option, but works well on small projects. Use a putty knife or scraper to dig away as much crud as possible, maybe use compressed air to get down to the really stubborn stuff. After that, soak or spray the area with:
Diesel fuel, kerosene or parts cleaner (ie: mineral spirits, naptha.) You already know the price of diesel. Kerosene is $20 to $30 per gallon, and parts cleaner costs $30 or more per gallon. Spritz the gunky area then walk away. Continue to wet the crud until it softens, then use a stiff brush or compressed air to blast away the softened grunge.
Brake cleaner, carburetor cleaner or other commercial aerosol engine de-greasers will definitely cut grease, but the cost per application gets expensive. Spray-on de-greasers cost more than $100 per gallon, if you do the math.
Engine oil is a slow-acting solvent, and contains detergents that help dissolve grease. You’re trading one mess for another, but in some cases it’s a viable alternative. If you don’t believe me, sometime when your hands are black with dried grease, rub your hands with a dollop of fresh engine oil. The oil will cut the grime and leave you with clean hands—once you get all the oil’s residue wiped away.
