Repairing flood vehicles

The first thing we need to say here at Autobahn Performance Inc. is that we would never knowingly buy or sell a flood vehicle.

Most of the time, no matter how cheaply you can purchase a flood damaged vehicle, it will not be a good deal. We repair various levels of flood vehicles. Here in South Florida and the coastal areas of Ft. Lauderdale, flash floods from rain or rising water are common. Fresh water flooding is much less damaging than salt water flooding. Modern Mercedes and other European vehicles are particularly susceptible to flood damage due to the state of the art electronic components and the modern trend to place these components in low lying areas due to weight distribution, center of gravity, and roll center calculations for the best handling and dynamics of the vehicle.

“The worst thing about a flood damaged vehicle is that there is usually no way to accurately estimate the cost or extent of the damage.”

The Mercedes 220 chassis vehicles (the S430, S500, S550 and S600) have thousands of dollars worth of control units and modules located under the rear seats, only 6 to 8 inches off the ground. If a vehicle is driven into a puddle that’s more than 6 inches deep, it’s very possible that water can intrude through leaking body plugs or seals and flood the area under the seats and carpets.

Often the customer doesn’t even know about the damage until some electronics malfunction. Meanwhile, the electronics and the electricity flowing through them that are surrounded by water, start to form acid (like inside a battery) that can ruin components, connectors and wires. When the damage is discovered it’s usually too late, especially if the damage is discovered due to a musty smell or odor in the vehicle; this would indicate that the moisture (along with the electrolysis) has been there long enough to mildew or form fungus.

The key to minimizing the damage from water intrusion or flooding is to (1) disconnect the electrical flow through water contaminated circuits. (Disconnecting the battery should be the first step.) and (2) get the water out and dried up as quickly as posible. A wet vacuum can be used to suck up excess water. The carpeting on a Mercedes can be up to 4 inches thick with the foam backing that is applied. This acts as a sponge and traps the water inside, leading to long term musty smells. At Autobahn Performance Inc. we have a portable de-humidifier that can be placed in the vehicle to draw the trapped moisture out of fabrics, carpets and foam under padding.

The next problem to deal with is the electrical connections and components. Any electrical part that is contaminated with water should be disconnected and dried with compressed air. The connectors should be cleaned with a solvent and scrubbed with a brush. Components can be cleaned with electrical cleaners. Corroded areas can be cleaned with vinyl bristle brushes and special solvents to remove surface corrosion.

Electrical connectors need to be disassembled (pins removed from the connector) and cleaned in solvent. Any connections on components or harnesses that appear to be damaged beyond repair should be replaced. Many electrical connectors and terminals are available from the dealer, but due to their relatively inexpensive cost and difficulty to look up correctly, most dealer parts personnel will try to sell a complete wiring harness. Wiring harnesses can cost upwards of $5000 and have required over 60 hours of labor to install on some of the vehicles we have repaired. At Autobahn we have access to most dealer parts programs and usually look up the wire connectors ourselves. Usually we can repair an expensive or labor intensive harness rather than replacing it. We also have affiliates that can repair some water damaged electrical components, or acquire used components and program them to the vehicle even if they are one time use / married to the vehicle or vehicle identification number.

The worst thing about a flood damaged vehicle is that there is usually no way to accurately estimate the cost or extent of the damage. Sometimes after the vehicle is repaired and everything seems to be fine, another area or problem arises due to the water damage and still more repairs are needed. We are good at working with insurance companies when they are involved. If insurance companies are not responsible for correcting the repairs, the best way to repair them is usually to repair one thing at a time, inform the customer of the time taken and what was accomplished, and then attack the next problem. With insurance company involvement we usually try to estimate all of the damaged areas and circuits but commonly require a supplement for additional damages that are uncovered or discovered later during the repair process.

One of the biggest misconceptions is that water damage is not covered by collision insurance. It usually is. If you are driving and you either cannot avoid or misjudge the depth of a puddle and hit it, you basically had an accident with a puddle of water, and that is usually covered by most policies — as long as you have more than comprehensive insurance.

This is a good time to mention that most customers, after they have had an accident or potential claim to their insurance, say, “I didn’t have collision insurance because the vehicle was only worth $XXX.XX dollars”. The way insurance works is that it’s cheaper to insure a vehicle that has a lower replacement cost or actual value and is a low risk vehicle.

Insurance isn’t for people with expensive vehicles; it’s for people who would have trouble repairing or replacing their vehicle if it were severely damaged or stolen.

Our Flood Vehicle Experiences

Mercedes-Benz flood vehicles

This is the rear floor (under the carpet) of a clean looking 2005 Mercedes E500 flood car. The brown stuff is dried up mud. This car’s interior looked in great shape and only had a slight smell of air freshener (to cover up the musty smell).

2005 Mercedes E500 flood car under carpet

Another common water damage problem is from the cowl panel (cavity between the engine firewall and the cabin firewall at the base of the windshield) of most Mercedes vehicles. This is where the climate control system draws its fresh air from. Older vehicles can have corrosion or rust here. This is almost imposible to repair once it has rusted through. It can be patched, but it will leak again within a few years. The replacement panels are available from Mercedes but are very difficult to weld in place and usually require removal of the dashboard, engine, and other components to install properly.

The cowl cavity also has problems from clogged drains. An incredible amount of water car run off the roof and windshield and collect in this cavity. Debris from leaves that collect on the windshield will restrict the drain to the point that the cavity fils with water and floods components in the cavity and overflows through the fresh air opening of the climate control system into the cabin of the vehicle.

The Mercedes SLK 170 chassis is especially suseptible to this condition. Even minor overflow from a restricted drain will cause water to flow across the blower motor, blower motor speed regulator, radio amplifier, and wire harness connectors. The water is sometimes not discovered for several days and components start to fail; blower motor speeds are erattic or stop altogether, radio stops playing, warning lights appear on the dash, and the vehicle begins to smell musty inside.

The carpet and floor insulation system on late model Mercedes is made of sponge-like foam that is molded to fill all of the irregular cavities under the carpet. The foam is over 6 inches thick in some areas. This foam sucks up and holds water like a sponge

Soaked Mercedes carpet underpadding

Mercedes carpet underpadding is like a sponge and is impossible to clean perfectly after water absorption.

This Mercedes-Benz SLK was flooded inside by the customer’s lawn sprinkler system. One of the sprinkler heads had come loose and the stream of water went high in the air and came down right on the windshield of the customer’s car. The water drains in the cowl at the base of the windshield were slightly clogged with debris so they couldn’t handle the huge volume of water.

The water overflowed through the fresh air opening of the a/c system and flooded the inside of the vehicle. We had to completely disassemble the interior of the vehicle and replace quite a few electronic components: Blower motor and regulator, radio amplifier, Tel-Aid control module / communication module, The radio (must have been short-circuited by the water-damaged amplifier) and the ABS / ETS module (mounted under the hood on the antilock brake pump. must also have been electrical short circuit related).

  • DSCN2056-300w
  • DSCN1965-300w
  • DSCN1961-300w
  • DSCN1957-300w
  • TelAid unit is under the drivers seat
  • DSCN1954-300w
  • DSCN1936-300w
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7

Unobstructed sprinkler water damaged this Mercedes-Benz SLK


Audi A4 cabriolets from 2003 up have a common problem with the rear window de-laminating or un-bonding from the convertible top material.

These have a glass rear window in the convertible top. The window is pressure bonded with an adhesive to the fabric or material of the top. The glass is known to come loose from the top material and if left un-noticed, rain water will funnel through the gap between the bottom of the glass and the top material. It will run down the rear seat back and flood the floor of the vehicle.

There’s a comfort control unit under the drivers seat (actually just in front of the drivers seat under the carpet) that gets flooded with water. Some vehicles have a transmission control unit under the carpet on the passenger side of the vehicle. CVT transmission vehicles have the transmission control unit inside the transmission (that’s another problem altogether).

If the water isn’t dealt with right away, the wire harness that runs throughout the car can be damaged beyond repair and require replacement. Replacement of this harness requires 80 hours labor! Two weeks of work just for the harness! It connects components at the front of the engine compartment to the rear taillights.

The window sealing is failing on 2 to 3 year old vehicles. I would be very upset if my vehicle needed a $4000 – $5000 convertible top every 2 or three years. Hopefully Audi has upgraded their materials to improve the longevity of these tops. The tops may be failing due to or warm climate here in South Florida, but how many convertibles are there sold in Alaska? Has anyone gotten Audi to participate in this repair after the vehicle was out of warranty? We’ve had several customers who had to pay for this repair on vehicles that were covered by a warranty but the claim was denied.