Driving your car unprepared through deep water is not advisable, unless it’s your only option. Then it’s still just as stupid and risky, but at least you have the excuse of not having had a choice. Modern cars are do not like water at all, either in their engine, exhaust or electronics.
But if you do get caught in a flash flood and you need to keep going, how much water can you go through safely?
I`m sure you’ve heard stories along the lines of “oh, I went through a big puddle at speed and my car died out and wouldn’t start,” but those are really rare occurrences. Most cars can do a bit of wading, and if you have crossover or SUV… a little bit more wading.
Typically, people tell you the maximum wading depth for an unprepared vehicle is right about the top of the rim (not the tire). If it gets any deeper than that, you really should kill the engine and try pushing your vehicle to dry land, then letting it dry off.
There are obviously variables that differentiate cars that can wade a bit from those that can’t at all. For instance, my 2002 Ford Mondeo diesel daily driver is not at all a good car to wade with.
Its intake sucks the air from somewhere around the left wheewell, and you can imagine that it’s easy for it to suck up water and potentially damage the engine. Rest assured, though, if this happens to you and don’t believe all the skeptics – if you get some water in through the intake of your (diesel) engine, and it seems dead, remove the glow plugs so that it has somewhere to spit out the water and try to start it.
If the amount of water ingested is not huge, you should be fine.
What you need to look out for is where your ECU, the battery and intake are located in the engine compartment. Their placement and level of insulation will determine the wade-worthiness of your car. The lower these key components are placed, the more vulnerable your car is.
I mentioned my own ride above because last week I was caught in a (flash) flood, on what used to be a road, in a main intersection. I was feeling safe that the water level was just below the top of the rim and the car was ploughing on fine; however, an SUV passed me coming the other way, creating a wake which went over the bonnet of my car and killed it.
It did start after over a week of letting it dry, taking out the glowplugs, clearing the engine of water, putting in a new air filter, replacing the glowplugs as they were all inexplicably dead and replacing the battery, but I was lucky as all the other posts I read on the matter talked about bent or valves conrods, as well as cracked and seized pistons – neither particularly peachy…
To sum up, make sure you know where the crucially exposed bits of your engine are and don’t get them wet. If the water level gets too high, immediately cut the engine and disconnect the battery. Let your car dry off as long as it takes and they usually just spring back to life. But really, if you can, avoid deep water at all costs as you don’t know what it might affect.
If you’ve had any such experiences in the past, do tell us about it!