Is an grimey, yucky, greasy messy engine a red flag? NO! Is a clean one a good sign? NO!
Ever open a hood and see a sparkling clean engine? Are you envious? Does it always mean the car you're looking at is in good condition? Hell, no. Even if it looks like Aunt Tillie has just waxed and polished it, is it an absolute good deal? Nope.
Sure, it looks great and your thinking, "man, this baby is clean and kewl looking." Not so fast. Car dealers and buyers might be using a little psychology on you.
A squeaky clean engine compartment makes any car, especially, a used car look newer and better maintained than it might be. All that glitters is not gold, remember.
Ask the seller for his maintenance records to make sure what you see is what you get. Don't ever judge the cleanliness of the engine compartment as a statement about how good the car is.
There are businesses who specifically do engine services such as cleaning and preparing cars for sale....of course, looks always matter but go into buying a car with the facts. Um, like Car Fax, we recommend getting a report on any car you are seriously interested in. Google them, they are, of course, are on the Net like your owner's manual. Yes, we know we are nags....just trying to save you your hard earned cash, folks!
There are some engine shops who do this cleaning service that claim a clean engine even runs a little cooler. But, realistically, aside from looking pretty to the eye, does an engine that glistens like new run better than one that's grubby? Probably not.
Of course, an engine that is oily, dirty and greasy can accumulate quite a mess of this stuff and therefore can trap some heat. It's probably not enough to cause an engine to overheat or even run hotter than it should.
An overheated engine is far more likely to occur due to cooling system issues or because the car was is towing too much weight or some other mechanical issue absolutely not related to Aunt Tillie doing a poor job.
Cleanliness always counts but lets be realistic. The internal combustion engine uses gas, oil, lots of oil, and various fluids that spill when you add to them, burn off because of the heat of igniting gasoline and making muck from various fluids dripping down the hot spots in your engine compartment.
However, that's not to discount the fact that a cleaner engine can help you or your mechanic diagnose the origin of a leak. Of course, a leak can be spotted more easily if the engine compartment is not gunked up meaning a small problem can be repaired before it's a big, ugly, expensive problem.
And cleaning away oil, grease and spills can prevent premature wear of plastic parts and rubber hoses. Common sense, no? And if you're a car gal or guy who enjoys some minor maintenance like checking the oil level, hoses or belts, a clean engine means you won't look like a grease monkey with your hands and clothes dirty and ruined when you lean in to add windshield wiper fluid.
Many mechanics, detail shops and plain best practices recommend using a degreaser and tools such as a vacuum with a small nozzle, compressed air or a toothbrush to get at hard-to-reach spots.
DO NOT blast your engine with a high-pressure hose or steam cleaner as tempting as that could be to get it done fast and easy. Pressure and moisture could cause electrical issues which can be very hard to diagnose and V-E-R-Y expensive because they involve hours of labor time.
Look, more than anything else, a clean engine has superficial appeal implying that the whole car is pristine. And since cars are detailed before they are sold even by private sellers, do your due diligence with maintenance records, get a mechanic to go and see any car you are considering purchasing, let them slap a meter on it and see what's cooking for real and don't let a clean engine have anything to do with your ultimate decision.