1. Homepage
  2. »
  3. Maintenance & Repairs
  4. »
  5. Why Your Car Won’t Start When the Engine is Flooded with Water

Why Your Car Won’t Start When the Engine is Flooded with Water

Car Engine Flooded with Water

Why Your Car Won’t Start When the Engine is Flooded with Water

Sometimes, Mother Nature can be mean. And by “mean”, we mean that she can really damage the car with her floods and heavy rain. This type of weather tends to lead to an accumulation of water inside the engine. Often, you will notice that if your car engine is flooded with water, it won’t start! That’s why we wrote this article to help you understand the causes and how you can attempt to fix the car in this instance.

Firstly, the car engine can get flooded with water in two ways. Driving through a deep puddle is the first one, and having your car parked in a flood-prone area is the second one. Small amounts of water are easily vaporized by the engine heat. However, large quantities of water can lead to either hydro-locking or short-circuiting of the electrical components inside. In either case, the fix is super difficult and you may need to get it towed to a mechanic.

Now, flooding also refers to the sparkplugs getting wet from excess fuel. In this case, the fix to the problem is easier. However, this specific article will talk about an engine flood caused by water. Let’s look at how you can assess the damage and figure out the next steps and solutions.

Assessing the damage

As mentioned earlier, excess water can get into your engine in two ways. If you are driving through a puddle or if your car gets caught in a flood. In the second case, it is important NOT to start the car before an inspection, or else you might damage the car more. For the first case, you will realize there is a problem if your engine suddenly sputters and stops working. Again, in this case, you might want to assess the damage before restarting the car.

Check the water line

Cars in shallow water
Cars in relatively shallow water: Image Credits: Pixabay

The most hazardous thing to happen during floods is for the water to enter the engine intake system. Then the water makes its way into the combustion chamber. If you are driving through a puddle, you can easily recognize how deep your car went. It is important for the water level to not be higher than the grill of the car. This increases the chances of water seepage into the engine.

If you aren’t sure how high the water reached (typically after a flood), try to check for the faint line the water left behind after the outside of the car has dried. This should give you an indication of whether your engine got flooded with water.

Check the electronics

Electronic components in cars | Image Credits: Pixabay

If the water didn’t get very high, then first check the electronics of the car. As mentioned before, there might be a chance that some circuits got short-circuited during the flooding. Remember, DO NOT TURN ON THE ENGINE. Before switching on the electronics, open the hood and check for water near the battery terminals. If it is slightly wet, use a dry cloth and dry it completely after disconnecting the battery.

Once dry, turn on the lights, infotainment system, and other electronics. You might notice that some warning lights (especially the check engine light) are still on or blinking. This might be indicative of some hydro-locking. Otherwise, if the rest of your electronics are working fine, there is a chance that your electronics are fine. However, they might still corrode later in the future and short circuit. So, keep an eye out for that.

Try cranking the engine

RPM Meter
RPM meter during cranking | Image Credits: Pixabay

If the electronics check out, you might want to test whether the car can start. But it is important not to try multiple times. Car engines work on the principle of compressing an air-fuel mixture. However, they aren’t designed to compress water or a dense air-water mixture. Thus, if it tries too hard, the pistons and other parts of the engine might break and cause irreparable damage.

If you didn’t get a “Check Engine” warning light, then you can try cranking the engine once. When you crank it if you hear the motor trying to crank but no response from the engine, then stop immediately. There might be water in the engine. Alternatively, if you don’t hear the starter motor at all, then there might be a short somewhere in the electronics. In this case, the engine flooded with water won’t start.

How to fix the problem

The steps above should give you a pretty good idea about how extensive the damage is. Depending on that, you can try to fix the problem yourself at home. However, as mentioned earlier, this fix is quite difficult and hence your best bet is to take the car to a mechanic. If you are confident, you can try the steps below.

Dry the car –  inside and out

Drying the car
Drying the inside of the car | Image Credits: Pixabay

If the water got into the car, there is a chance that the electronics in the passenger cabin are also affected. You want to roll down the windows, pop the hood and let the car dry as quickly as possible. You can use a wet vacuum cleaner to suck out any still water from different parts of the body. It is generally a good idea not to use compressed air as you might push the water deeper inside the circuits.

Leaving it out in the sun for a few hours should do the trick. It might even help evaporate any moisture inside the engine or its electronics.

Wipe the sparkplugs!

mechanic with a spark plug
Dry the tip of the spark plug | Image Credits: Pixabay

Sometimes the problem isn’t so severe. The spark plugs get wet, and they cannot generate a spark. To solve this, disconnect the battery and take out the sparkplugs from the car. Wipe the tips off properly with a dry cloth and ensure there is no moisture around them. Let them dry off properly including the ignition coils and then assemble them back together.

Taking the plugs out should also give you a peek into how much water may have gotten inside the car. If it’s not too much, you can try to crank the engine one last time. If it still does not work, you probably have a hydro-lock on your hands.

Crank the engine without sparkplugs

Starter Motor
Use the Starter Motor to crank the engine | Image Credits: Pixabay

While not advisable, you could still try to save the engine from a hydro-lock. To do this, you want to keep the sparkplugs out and try to crank the engine with the starter motor. Without the sparkplug, there is no compression created as there’s no seal. This leads to the water slowly being ejected from the engine. It might fill up with some fuel though. Fortunately, the fuel can evaporate rather easily.

After a while, you can try cranking with the sparkplugs back inside and see if the engine turns on or not. Needless to say, if it doesn’t, the best idea is to take the car to an authorized dealership and let them solve it.

Replace the engine fluids

Engine Oil Cap
Engine Oil Cap | Image Credits: Pixabay

If your car was indeed submerged under water, there is a high chance that the lubricants and fuel used in the car have been contaminated. If the car miraculously starts working, after the previous step, then stop the car and take out some time to check fluid contamination.

To check for oil contamination, you can take out the dipstick and check if there is any water residue on the stick. For the fuel, you can try to siphon off some fuel from the bottom of the fuel tank and check if there is any water present in the fuel. This can be checked easily if you wait for the siphoned fuel to settle for a while as gasoline floats on the water.

In case any of the fluids are contaminated, you will have to flush the entire fuel/oil tank and replace the oil. This is important as otherwise, it might cause more problems down the line.

Fix the electrical shorts

car wires
Electrical wires can be shorted | Image Credits: Pixabay

If there is indeed an electrical short circuit issue, then the first task would be to find where the short is located. This can be done with the help of a multimeter. Unfortunately, this is rather tedious. The warning signs on the OBD might give you a hint as to where it exists. You could also check the error messages using an OBD2 scanner.

Once found, you will have to completely dry the area. Then you might have to create a new connection or replace the part completely to prevent future corrosion and short circuits. Short circuits can further lead to the blowing of fuses too!

Final Thoughts

Having your car get trapped in a flood-like situation is quite unfortunate. There are very few cars built to withstand such conditions. As you can see, it is extremely hard to fix your car if the engine is flooded with water and it won’t start. Remember, trying to start your car is the last thing you should do since it might damage the engine further. Then you might have to completely replace the engine which will cost a pretty penny.

Therefore, our advice would be to get it checked immediately at a trusted auto mechanic. It is equally important to have good insurance coverage in such situations as even the mechanic might end up charging a lot. We hope that this article helped shed some light on how to diagnose the extent of damage and how to attempt to fix it if you are brave enough. With any luck, your car never has to go for a swim and can weather any storm that comes.

Related articles