Fix a Car That Has Been in a Flood

When a car has been caught up in a flood, water may get into areas it shouldn't (such as the engine or fuel system). This guide will tell you what you should do/check if this ever happens to you.


  1. Do not attempt to start the car. Water may have got in to the engine. If this has happened and you start the car, you will bend the pistons and the engine will have to be rebuilt which is very expensive.
  2. Check the air filter. If the air filter has water in it or feels wet, it needs to replaced. It also means that water has got into the engine.
  3. Check the fluids for any water contamination. This includes: engine oil, automatic transmission fluid, power steering, coolant and the brake fluid reservoir.
    • If water has got into these systems, the fluids must be replaced or they can stop certain parts functioning causing damage to vital systems or cause danger to the driver.
  4. Remove all the spark plugs (gasoline/petrol) or glow plugs (diesels) then crank the engine.
    • The car won't start but (if water has gotten into your engine) you should see water be ejected out of the engine. Crank for 10 seconds at a time and wait a minute before repeating. Repeat until no more water comes out of the engine.
  5. Put the spark plugs (gasoline petrol) or glow plugs (diesel) back into the engine.
    • Spark plug (pictured below and is the plug on the right in the image)
    • Glow plug (pictured above)
  6. Check all the electrical systems.
    • Water and electricity do not mix. If there are any corroded wires etc, the car may not start or will short the car's ECU (Engine Control Unit) which is expensive to repair. All the wires must be check thoroughly
  7. After this, try to start the car properly. Hopefully the car will just start up. If it doesn't or it has problems idling, then it may need a new computer.
  8. Dry the interior using a hair dryer.
  9. If the does start and there are no electrical faults, replace the fluids after 1,000 miles of driving.
    • This is to make sure the car has absolutely no contamination in its fluids.


  • When putting the new oil filter on, rub some oil around the gasket to ensure the new filter fits on the engine snugly. You should screw the oil filter in place by hand first and then use a wrench to tighten it further. Don't do it too tight or you could damage the filter.


  • As stated above, do not try to start the car until you have checked everything. The reason this is repeated is because it cannot be stressed how important this piece of advice is. If you need to move the car, push it (if safe to do so) or tow the car.
  • When changing the oil, the filter must be changed as well (same applies for the automatic transmission fluid).
  • When doing step 4, you must stop cranking the engine after 10 seconds or you could burn the starter motor out.

Things You'll Need

  • Oil (check your car's handbook to see what the manufacturer recommends for your engine)
  • Anti freeze (for the coolant)
  • Automatic Transmission fluid (if your car is an automatic)
  • Power Steering Fluid (if your car uses hydraulic power steering)
  • Brake fluid
  • Fuel (Use the manufacturers recommend fuel type for your car)
  • Drain pan (for the old fluids to drain into)
  • Wrench (for putting the new oil filter on)

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