What To Do When the Flood Waters Rise

This is that festive season of nearly endless flash flood warnings, that lovely anxiety-inducing chime of your phone while you race to get your vehicle to the neutral ground as fast as you possibly can. If it hasn’t happened to you or someone you know yet, it’s only a matter of time before your vehicle is the victim of the next gradually intensifying, sudden extreme weather event. Not only is getting street water inside the cab of your car really gross, if the water rises above your engine air vent, you could easily be dealing with problems beyond even what any highly capable mechanic would want to take on.

Engines are really amazing machines 

They are designed not only to withstand very high heat but also to harness power efficiently so you can get to that iced coffee place you love so much. Engines are essentially built to contain thousands of explosions per minute. These explosions cause energy to release. Instead of wasting this energy on friction, which means excessive heat and damage to your engine parts, we want that power to get us moving forward with our lives (or at least our day).

Engine oil is what keeps the whole system efficient. It lubricates the parts that move in your engine, reducing the amount of friction (energy loss) that occurs. The oil is pumped through many tiny chambers and pathways in order to be distributed evenly through all moving parts. Engine oil is a pretty important part of your vehicle’s dependability.

Water is oil’s natural enemy, as you likely learned in your elementary school science class or perhaps because you watched countless hours of publicly-funded educational childrens’ programming about a magical yellow bus and a fanatical teacher whose hair you are still jealous of to this day. Water does not have the same lubrication properties as oil, which means lots of friction. Friction means lots of heat and lots of damage—like lots and lots of damage. Moral of the story is, don’t run water through your engine if you don’t want those contained explosions to become uncontained explosions.

Do not try to start your car while it is still flooded

This also goes for driving through flood waters, especially if your car sits low to the ground. If you are particularly worried about this, look up where your engine air intake is located on your vehicle and make sure to keep that area above water at all times. If you were away from your car while the flooding happened, check for flood lines around the area to see how high the water got and if you should be concerned.

Check your oil

You can use the dipstick to get a glimpse of how much water actually made it into the engine. Pull out your dipstick, wipe it down with a clean rag, and stick it back all the way down. Now pull out that dipstick again and, after making a lot of very inappropriate jokes about that entire process, take a look at it. Any sign of water is a bad sign and you will want to investigate further by accessing the oil drain plug located at the bottom of the oil pan underneath your car.

If your vehicle has sat for any amount of time after being flooded, all the water should be at the bottom of the engine. In theory, if you were stranded on the side of a desolate road and just needed to get your car moving to call for help, you could open up your oil drain plug, watch for the water to drain out, and quickly put the drain plug back in, saving the majority of your oil and allowing you to drive your vehicle to civilization. Again, theoretically this could work if you had absolutely no other option, so keep this trick in your toolbox. However, if this near-apocalyptic situation is not where you find yourself, drain all of the oil, change the oil filter, and refill your engine with all new oil. New oil is cheaper than a new engine. Just like the oil, you will also want to check your transmission fluid for water and drain and refill if you find it. If you have a four-wheel-drive vehicle—you probably already know all this but in case you don’t—you will also want to drain and replace your rear differential fluid.

Electrical components

As opposed to being oil’s enemy, water loves electricity. But like, way too much. We do not want to run electricity through any part of our electrical system while there is still moisture around. Electricity can jump through the moisture to spots where it shouldn’t be, ending up in too many places at once or all in one place at the same time. This can cause major electrical problems or minor persistent ones. These can be so elusive you will want to drive your car off a cliff out of sheer frustration like you’re in some Chuck Jones cartoon.

Unfortunately, the newer your car, the more electrical components you will have. The simplest and easiest way to handle this is to just let everything dry out for a day or two before even trying to start it, if the weather cooperates. If you have an older vehicle you will likely be able to see most, if not all, of the electrical components, which makes it really easy to make sure everything is dry before starting your car. In any case, you can use compressed air to blow out any water droplets you might find that you can’t reach with a towel. Before you start poking around, it’s a good habit to disconnect the negative battery cable any time you are working on your vehicle. The two places you can start your checks for excess moisture would be your fuse box and your distributor cap; note the latter applies more to older vehicles.

Water in the cylinders

If your car was submerged or nearly submerged in water, there could be water in the cylinders. Do not panic: We can use the engine to get this water out of there. You will want to remove the spark plugs. Before you do anything, label your spark plug wires with some tape and a marker in some kind of numerical order. Make sure to also take pictures to remember your numbering system so the spark plug wires make it back to their corresponding spark plug. Take the time to be organized like this early on to give future you—the one that’s tired from working on the car all day—a break when putting the whole thing back together again. Next, pull off all the rubber boots, recognizable as spark plug hats, from the spark plugs themselves. After this you will need to use a spark plug socket that fits your spark plugs and a ratchet to take out the spark plugs themselves. Now for the fun part: Reconnect your negative battery cable and crank your engine by turning the key in the ignition to the start position. The starter will turn your engine over, moving the pistons, and pumping the water out of the spark plug holes. Depending on which way your spark plugs are facing, the splash zone may be quite large, so I would advise you to stand back behind the hood and not directly in front of the engine bay.

After you have put all the spark plugs back and replaced their cute little rubber hats, making sure to reconnect the wires in the correct order, there are a few more things you can check. If you are really keen, consider checking and even flushing your power steering fluid, brake fluid, and fuel systems. These can be tedious tasks, but the cost of a few hours of your time and all new fluids is drastically cheaper than needing the entire system replaced because of some debris clogging something up. If the wheels of your vehicle stood in flood waters for a while, you may also want to check the wheel bearings and re-grease anything that needs it.

If you do not want to, or just don’t have the time or capacity to do this work yourself, don’t be discouraged. It’s still important to understand how the parts of a car could be affected by a flood event in order to communicate with a mechanic effectively, and also not get ripped off. Knowing what can go wrong, what you feel comfortable working on, and understanding just a few of these mechanical basics is all part of being prepared for these ever-increasing freak weather events, not only for yourself but for our community as a whole.

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illustrations by Deanna Larmeu