9 Common Issues with Cars That Have Been in a Flood

Millions of cars and trucks have been damaged in flood events worldwide. Some are damaged beyond repair, while others are reconditioned and sold as lightly used to a new owner.

Flooded cars can look well taken care of but hide many problems under the surface. We’ve collected the common problems that indicate a car has been in a flood, so you can steer clear of it.

#1 – Water Stains In Hidden Places

Obviously, water is the main problem with a flood-damaged car, and water will leave a stain on surfaces after it has left. The signs that water contacted the vehicle can be somewhat easy to cover up on exterior surfaces.

You can generally wash the car and clean off the painted surfaces to eliminate the chance of a water stain. One way to find the water stains on the exterior of the car is to look in the hard-to-reach places.

Look behind body panels where a car wash would miss. You may find a water line in the door jambs, behind the taillights, or on the backside of the bumpers.

Water stains on the interior can be harder to find if the soft surfaces like carpeting and upholstery have been removed and cleaned.

If water has been left on the soft parts of the interior, they will soak in water and contaminants that won’t be easy to remove with upholstery cleaner. It may be required to replace everything to hide the fact that the car has been through a flood.

#2 – Contamination Left Behind

Watch the news feed of flood waters traveling and see how much debris and contamination it carries.

Contamination, such as mud, debris, and oil will collect in your car. Most owners reconditioning a car that has been in a flood will remove the carpets and clean or replace them.

What they rarely clean is the contamination evidence that is left behind in the hard-to-reach places.

Moisture left in a car can quickly turn into mold that gives off a musty smell. If you find water residue lines in obscure places or smell a musty odor, be wary of buying the car until you know for sure whether the car has been through a flood.

#3 – The Engine Is Damaged

Water isn’t combustible, so it should never be in your engine cylinders.

Flood events can submerge your engine in water, and that water will enter the engine and fill it full of water. Water can cause corrosion to form inside the engine, which can lead to engine failure in the future.

One of the biggest mistakes car owners make is trying to drive through flooded areas. A hydrostatic lock can ruin an engine quickly if a running engine ingests water.

Water doesn’t compress like air, and a running engine will attempt to compress the water in the cylinders if it is running. That attempt at compression will typically bend the piston rods and cause catastrophic damage inside the engine.

Another failure mode can be water penetrating electrical components like the starter, alternator, and electrical connections.

Most electronics can be dried without damage, but salt water can leave residue behind that can cause electrical fires. Any engine or electronics that have been submerged in water should be approached with hesitation and caution.

#4 – The Wiring Is Damaged

Most cars have wiring harnesses front to back to power the electronics and lighting.

Water will penetrate the harnesses and become trapped. It will also bring oils and other water-borne contaminants that can linger after the flood event is over. W

hen water contaminates the wiring harnesses, they can be significantly damaged and may need to be replaced rather than reconditioned.

Read also, Electrical Wiring Problems? 9 Common Issues & Fixes

#5 – Complete Electrical System Damage

Your car’s electrical system is made up of electrical components, wiring harnesses, and protected systems.

Water can cause short circuits at the battery if it is submerged in water. It can also cause shorts in every fuse box in the car.

These short circuits can cause fuses to blow, which may protect sensitive electrical components. In some cases, the fuses can’t protect all electronics and complete systems can be overloaded with power surges from flood waters.

Repairing electrical system damage may take a significant amount of time to inspect each power circuit for damage. It may be easier to replace every electrical harness in the car, and that can be a significant cost.

#6 – The Transmission Is Damaged

The transmission is one of the lowest parts of the car, which means it can be one of the first major components to touch water in a flood event.

The transmission is sealed, but water can seep into the cases if the transmission is submerged in water. The transmission contains metal gears, synchros, and clutches that can corrode from water exposure, which may later fail under power from the engine.

At a minimum, the oil in the transmission system will be contaminated with water and need to be replaced.

The transmission isn’t the only housing under your car or truck. You may have differentials or a transfer case that contains oil.

Water intrusion in these housings will cause the gear oil to mix with water and the seals may swell until they fail. These housings may contain electrical components that will corrode and fail after contacting water.

A flood event may require these housing to be rebuilt with new internal components.

#7 – Rust Forms Easily

Rust is one of the major problems long after a flood event is over. Many of the surfaces on your car and its components aren’t well protected from corrosion.

A flood event will submerge these components in water, and then corrosion will immediately start on everything that has minimal protection.

#8 – A Damaged Exhaust System

Most exhaust systems are made of steel, whether that is 100% carbon steel or an alloy mix to reduce the cost of manufacturing.

Rarely are exhaust components coated in a corrosion prevention material, and flood waters take advantage of that lack of coating.

The exterior surface of an exhaust system can corrode immediately from flood waters, and that corrosion will eventually rust the exhaust system through the metal.

Exterior corrosion is common with exhaust systems, especially in areas where salt water is prevalent. One major area of concern is when flood water fills the exhaust system with contaminating water.

The mufflers in the exhaust system have internal packing material to dampen sound, and these soft materials can absorb the flood water. This will cause corrosion inside the mufflers, and it can prevent the exhaust gas from passing through the mufflers if the car is started.

The catalytic converters in the exhaust system can also be clogged by flood water and any contaminants it carries. Oily residue can coat the internal metals in a catalytic converter and render it useless. It will mostly cause a Check Engine Light (CEL) to illuminate if it allows exhaust gas to pass through it.

#9 – You Can’t Find Insurance

Buying a known flood vehicle can have a bigger impact that lasts beyond that initial purchase. Most insurance companies will not insure a flooded vehicle because they have a high potential for future problems.

Those companies that do offer coverage for reconditioned flood vehicles may increase the insurance rates to a barely affordable price level.

If you find a known flood vehicle at an auction or through a private owner, be sure to check what the insurance would cost before making that purchase. Your current insurance provider may decline to cover a flooded car, and that low-budget purchase can cost you significantly more to own than you initially thought.

Some insurance companies may ask for additional inspection of the flooded car before they will offer an insurance policy for it.

A local service center can inspect the car for flood damage including contamination left behind from receding water, saltwater intrusion if the car was in a coastal area at the time of the flood, and major component corrosion.

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