By Pep Sanchez
Whether it’s engine oil, coolant, or fuel, the engine seizes to function with the loss of its fluids. That’s obvious enough. But what happens exactly? In this installment of Auto Repair Blogs, we’ll look into how an engine breaks down when fluids dry up.
Engines, being the complex machines like they are, have quite a number of adjoining components whose surfaces slip, slide, push, pull, mesh, brush, and grind against each other. Between these surface, kinetic energy is lost to heat because of friction, and no matter how much these surfaces are mirror-polished, they’re still as gritty as sandpaper at microscopic levels.
This is where lubrication like engine oil plays its importance. Oil molecules buffer between two mating surfaces and behave like microscopic ball bearings greatly reducing friction. Less friction, less wear-and-tear and also less heat generated. Engine oil also has the additional function of carrying away heat and accumulated particles that could worsen wear on parts. That’s why an engine should always be sufficiently lubricated with the right grade and right amount of oil.
How does an engine destroy itself in the absence of lubrication? Most mechanics observe initial destruction in the following areas.
One is the main bearings of the crankshaft where the piston rods are connected to. These bearings depend on having a thin film of oil between their surfaces and keep the surface from rubbing while the piston pushes the crank around at several thousands of revolutions a minute. Without oil, excessive wear and hot spots are generated on the mating surfaces, eventually leading to intense vibration and fracturing of metal parts.
Another critical area for lubrication is between the piston and cylinder walls. These are precision machined for close to perfect fit and lost of fluid will cause the surfaces to wear away to a point when the piston rings will fail to seal the cylinder for compression, or the surfaces could just melt, seizing the piston.
Valves can also get “welded” into place then properly crushed by the closing pistons. Cam lobes get scarred, drive chains snap-off, and head gasket seals broken. A car will actually run with just the residual oil left on its internal surfaces but only for a few minutes. After that, expect engine parts to get blown out of the engine in spectacular fashion.
You’re unlikely to experience unintentionally running your car with absolutely no oil but running your car with an inadequate amount of oil (like when your car excessively burns oil or has a leak) or running your car with old dirty oil (not changing your oil enough) will have the same effect in the long-term. So make sure your oil levels are up to OEM specs, change your oil regularly, and if you’re losing oil as you drive, have your car checked by a trusted auto repair shop.
Running your car with no coolant will also be detrimental to the engine (but with less spectacular effect than running with no oil). In fact, most engine management systems will allow you to run your car with low levels of coolant in “limp mode” to give you a way home or at least, to the nearest auto repair shop. In some systems, the engine is shut-off from doing further damage to itself when you’ve totally lost coolant.
But if these fail-safes are defeated or unavailable, several things can happen to an engine for continuously running it in high temperatures. Cylinder heads can get irreparably warped or the head gasket can melt, causing a vacuum or fluid leaks that will stall an engine. Lack of coolant can also cause the engine to burn its own oil, making the oil lose its lubricity and eventually causing the internal mechanical parts to fail.
If somehow the engine and its oil remain intact, the high operational heat will surely cause plastic and rubber parts to melt, like that of electrical wiring insulation, fuel injectors, and hoses. In turn, this will either cripple an engine or worst, start a fire.
There’s a lot of reason why you could lose some or all of your coolant. Your radiator can spring a leak due to corrosion or front-end collision, radiator hoses can leak or snap-off, sometimes engines can bleed coolant internally. If your car shows signs of overheating (like the temp gauge maxing-out to “H”), it’s time to have your car checked by a reliable mechanic.
Most fuel misers will recommend not filling up the tank but instead, run on low but take frequent trips to the gas station. You save on fuel by saving on weight. But this strategy risks running your car on empty. Question is: Is it bad to run your car on empty? Most mechanics will say yes, and here are the prevailing reasons why.
One, sediments will form in the gas tank over time. These could be made of impurities from using low-grade fuel, or corrosion that had developed in the inner walls of the gas tank that have dissolved in the gasoline, or microbial contamination in certain types of fuel.
There are no drain plugs or removable pans in the underside of fuel tanks and so removing accumulated sediments is a difficult procedure that’s rarely pursued. Most of these impurities settle harmlessly to the bottom of the tank and if any impurities are picked up by the fuel pump, the fuel filter does its thing to keep them out of the rest of the fuel line.
But when you run on empty, there’s a tendency for the fuel pump to siphon gas with a higher concentration of impurities. This will not only clog the fuel-filter prematurely (which would starve the engine of fuel) but increase the likelihood that impurities will get pass the filter and clog the fuel injectors.
Another risk is that most modern fuel tanks are made of durable plastic or aluminum, but if your fuel tank is made of steel, carrying low amounts of gasoline means the inside walls are bathed less on fuel, which increases the risk of corrosion to develop and therefore more impurities into the mix.
One final risk of running your car dry on fuel is damaging the fuel pump. The fuel pump is a sealed electric motor that’s cooled by the flowing gasoline it pumps. Prolonged use without its coolant may cause it to burn-out. Being sealed, it’s unlikely that a burned-out motor will start a fire but getting to the pump and replacing it, is usually a very involved and expensive ordeal.
So never run on empty. Remember that fuel is actually cheaper in the long run than the cost of repairs.