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Here's why you should never drive on flooded roads

When the going gets wet, find an alternate route
(and if you can't, these tips will help)

  • Choosing a car at dealership. Thoughtful grey hair man in formalwear leaning at the car and looking away

We?ve all seen video of drivers plowing through flooded roads. Some make it safely to the other side and some don?t and have to be rescued. At worst, vehicles may be washed away or overturn in strong currents causing loss of life. And of course some, like this? Ferrari driver who got caught in Toronto’s epic July 8 flood, go on to become iconic.

The safest and wisest thing to do when facing a flooded road is simply to find another route. Here?s why it?s never a good idea to take the risk:

  • The water may be hiding a sinkhole, debris or a washed-out road ? all of which could halt your progress mid-way.
  • Cars today have little ground clearance before water interferes with the exhaust system or seeps into the passenger cabin.
  • Water can cause severe engine or electrical system damage. Once it hits the fan or rotating belt, water is thrown everywhere inside the engine compartment.
  • African safari-type vehicles, with a roof-height snorkel for the engine air intake, can withstand deep water. But most regular vehicles risk extensive damage if water is sucked into the engine.
  • Flowing water is extremely dangerous. A small trickle over the road may be a precursor to an oncoming torrent after you start crossing.
  • Vehicles may begin to float in just 30 cm of water, causing loss of control. Most autos, including SUVs, can float away in just 60 cm of fast-flowing water.
  • Hydroplaning can occur with even the slightest bit of water cover on paved roads.
  • Driving at speed into 15 cm of water feels much like a crash, as you decelerate instantaneously on impact, which can cause loss of control.

Don?t attempt to cross if water reaches above your door bottom. Also, keep in mind that brakes don?t work well, or may fail, if wheels are immersed.

If you insist on driving through regardless of the hazards, do it one car at a time. Don?t get trapped behind another car in case it stalls or gets stuck mid-way. Also, don?t cross while an oncoming vehicle is making the attempt, since steering is haphazard at best.

Don?t stop or change gears during your attempt, as water may flow back up the exhaust and cause stalling or engine damage.

Once on the other side, your troubles may have just begun. Water in the cylinders may have to be drained and you should change your oil and tranny fluid as a precaution. Water contamination in either fluid can cause severe damage.

If your vehicle has been sitting in, or driven through, deep water, it?s a good idea to have it checked by your mechanic. Running it, or even just trying to start it, may cause severe damage if water has gone anywhere it shouldn?t.

If the interior was compromised by flood waters, have it cleaned and dried out as soon as possible to prevent mould growth and a resulting ?swamp? smell.

Email your non-mechanical questions to Eric Lai at wheels@thestar.ca. Due to the volume of mail, personal replies cannot be provided

  • Here's why you should never drive on flooded roads CI-STORM15 12-07-15 - TORONTO, ONTARIO - Cars proceed with caution through the swamped underpass on Windermere Ave, which passes under the Gardiner Expressway. Parts of Toronto were hit by severe rain storms in the afternoon, Sunday, July 15, 2012, causing a number of flooded underpasses and roadways. (RICK MADONIK/TORONTO STAR)