How can an engine be flooded?

I have a 2000 Corolla CE and had to travel through torrential rains today and some of the roads were flooded (I’d say about 1 feet flooded).

How would an engine get flooded? Like where would the water go into the engine? (at least on my corolla). Scotty Kilmer, a popular mechanic, said that they are intake vents on the bottom where water can get sucked into the engine and that because water does not compress, it might blow a hole in the engine.

If I did have to go through about 1-2 ft of water, is there any advice I should follow?


Car does not=boat.


The engine has to take air into itself and mix it with atomized fuel to run. The air enters the engine at the top, but the air can be drawn into the engine COMPARTMENT from anywhere. Typically there is a large hose that runs from the top of the engine to somewhere at the front of the car. That may mean ANYWHERE at the front of the car. If you drive through water high enough to cover the intake hose your engine will suck water into the cylinders and try to compress it. Water isn’t compressible, so it’ll just break your engine. It’s simply the power of hydraulics.
You could make sure your air intake is high enough to stay out of the water, but that is a lot harder than it sounds on an emission controlled automobile, and you don’t seem to be too long on automotive engineering skills. Your best bet is to stay out of deep water.

If water is more than say, a foot deep, it’s better to avoid it. Not only can you destroy your car, but in flood situations there can be powerful undercurrents that can sweep your car (or yourself) away in deceptively shallow water.

If you absolutely must go through some deep water, my advice would be to never stop in the water, but don’t blast through it either. Maintain a constant slow speed, not racing your engine. If you have a vehicle with low ground clearance, I would turn around and find another route.

In addition to killing your engine, you can get water in your transmission, electrical connectors, etc. While systems on a vehicle are meant to be weatherproof, that does not include submersion in water.

Do not drive through flooded roads for several reasons. 1) You’re much more likely to mis-judge the depth of the flooded waters, and the car will stall if the ignition system gets wet or the car sucks water into the air intake, causing damaging hydrolock. 2) Flood currents can flip and carry a car, even in 1 foot or less of flooded roads. This is a function of the strength of the current. 3) The long term effects of water infiltration, if your successful in crossing the flooded area, could cause premature failure. Anything submergrd could retain water for a while and cause further damage.

I can think of no good reason why someone would ever HAVE to drive through 1 - 2 feet of water in a Corolla. Ever. Turn around, go back, find a safe route, whatever.

Like I said: Don’t.

When you turn the key, will the engine crank? Will it start? Open your air filter box. Is it full of water?? THIS is where water can get inside your engine. Look for the air intake tube that feeds air into the air filter box. Did that tube go under water?? If the air filter is dry, chances are no serious damage was done. The ignition system might be wet, causing a no-start condition. It can be dried out…

Don’t even think about going through two feet of water. Damage is very likely (ignoring the safety issues already mentioned here). Depending on the car, you might be able to go through one foot of water, but damage is still possible, so I wouldn’t.

It was a narrow road and the road itself wasn’t flooded but there were large flooded spots caused by the drainage sewer system. The rain water from the sewer system was actually draining into the road and flooding areas of it.

I made sure to go slow and the car starts fine today and runs good so probably no serious damage was done.

If water had been sucked into the engine it would STOP. Immediately. So it sounds like you’re OK.

Are you in Colorado, by chance?

No, DC.

Another problem with driving through water a foot or so deep is that water and grit can creep into wheel bearings, suspension and steering components, electrical connectors, driveline components, transmission or differential vents, etc, etc and create problems later on.
Those problems may not show up for weeks, months, or even years.

If your Corolla is like my Matrix the engine air intake is next to the battery, about 3ft off the ground, so driving in 1ft of water won’t likely drown the engine.
However, 1ft of water will hit the floor pan of the car, making it easy to be swept away in a cross current.
It’s best to NEVER drive across streaming water.

I can’t agree enough with the posters who warn you about being swept away in deep water. People die all the time from going into water as little as 4" deep. Fast moving water at 4" can sweep your car into a creek or drainage ditch where your chances of survival are very slim.

You also don’t know if a sink hole has developed somewhere under the water. A few years ago, a woman was driving down a city street in the rain. There was actually quite a bit of traffic on the street, but she made a right turn onto a side street and as she pulled to the right to make the turn, her car fell into a sink hole that had formed only moments earlier. She was lucky that a man waiting for the bus managed to rescue her before her car sunk in too deep.

Not only can water get sucked into the engine and ruin it, it doesn’t take much water to float a car and off you go. You don’t know the condition of the roadway under the water either. No, you don’t HAVE to drive through water. Just turn around or wait it out. So you think you have to drive through two feet of water, it stalls in the middle, and there you sit. Then you wade back to shore again, try to get the car towed eventually if it doesn’t get washed downstream, and then have the damage assessed. Now is it really worth it??

The term “flooded engine” has for a hundred years meant that too much fuel has been pulled into the cylinders, wetting the plugs and preventing them from firing. With fuel injection that problem is so rare that most drivers under the age of 40 are unaware of the situation. And certainly water entering the engine through any opening would be “flooding.” Luckily the engine cranks and runs now so it is likely no internal damage has been done. It might be worthwhile to inspect the air filter as it might have become waterlogged and allowed enough moisture to be pulled into the combustion chambers to cause the engine to run poorly and once wet the paper filter might deteriorate and get sucked into the MAF sensor while failing to filter out dirt. I recall several Corollas with the air filter on the drivers side just behind the headlight with the intake port facing a hole in the radiator support where water could easily be splashed up to be drawn in with the air.

I agree with those who say one of the biggest risks is unseen holes in the water. Elsewhere on the Web is a picture of a car, I think in Colorado, sitting in the driveway. Inches behind it there is maybe an 8 foot drop where the flash flood washed away the roadway. Visually, that water might look like it’s only a few inches deep, but it might be several feet deep and you can’t see it.

There are few circumstances where you can’t afford to wait, even overnight, rather than risk your life.