Floodwaters from Hurricanes Harvey and Irma inundated hundreds of thousands of cars and trucks, ruining many of them, news reports say. Modern motor vehicles incorporate so much electrical and electronic circuitry that is not sealed against water, and are so complex, that the vehicles cannot be salvaged. Experts warn that some will be dried out, cleaned up, made to run again, and sent north to be sold to unwary consumers. So, beware!
But heavy trucks and trailers sit higher than cars, and if they’ve been in relatively shallow water and circuitry and onboard computers are not damaged, they might still be serviceable. Not right away, though, emphasizes Bendix Heavy Vehicle systems, which has issued guidelines for repairing air brake and wheel-end components exposed to flood waters.
“At the top of the list is the question of whether the floodwater was salt water,” said Jim Szudy, Bendix’s engineering manager for advanced systems engineering, in a press release. “If the answer is yes, then you should immediately begin replacing parts."
"Pneumatic air brake valves that have been submerged have likely lost their lubrication, for example. Couple that with the extremely corrosive nature of salt water, and these valves would be at much higher risk for sudden and premature malfunction," he continued. "Any brake system valve that’s been submerged in sea water should be replaced, along with air compressors, air reservoirs, antilock brake system (ABS) relay modulators, and brake actuators.”
Salt water also makes corrosion of wheel-end parts more likely, leading to increased chances of rust-jacking and damage to other components. Again, Bendix recommends a complete replacement to prevent future failure.
It’s best to do all those things if the vehicle was in a coastal area, and it’s not clear whether water submergence was by fresh water or salt water, the Bendix guidelines say. During the replacement of any pneumatic system components, all contaminated air hoses should be disconnected, flushed with clean water, and blown out with air pressure to remove contaminants.
If it’s certain the truck or trailer was submerged in fresh water, power-wash the vehicle and trailer, including the foundation brakes, to assist in determining the condition of components. Then, mark and remove the connectors at the first valve in the system from the front, inspecting as work proceeds.
Carefully blow clean, dry air from a shop air compressor through the hoses and watch for evidence of water or contamination. Continue to inspect all the valves in the air brake system, removing one service and control hose from each to inspect. Replace any non-functioning valves.
Wheel ends have both mechanical and ABS electronic parts, so examine them for the presence of water. Water increases the possibility of rust-jacking (corrosion between lining material and the shoe table) on drum brakes, and can also pool in drums when left standing, leading to corrosion. And ensure the integrity of the friction coupling between the friction and disc or drum.
Verify that no water has entered the chamber through the airlines by removing fittings and mounting stud nuts and orient ports down. If present, drain and reinstall them. Follow the appropriate wheel-end re-lubrication procedures, including re-greasing the slack adjusters.
For the ABS parts:
- Conduct a diagnostic download on the system using a tool such as Bendix ACom diagnostics software for both the ABS and stability (if equipped) controllers. In most cases, electronics will validate through self-check: If the electronic control unit (ECU) is operable, it will check the necessary solenoids, sensor, harnesses, etc.
- Inspect the seven-pin electrical connectors on the tractor and trailer. Also inspect all glad hands and the supply and control hoses, because water and contaminants can pass into the air brake system through unprotected glad hands.
- Remember that pressure-washing can move sensors and speed rings. Be sure they’re back in their proper positions.
On power units, if fresh water has entered the air compressor or dryer through the air system intakes, do not attempt to start the engine. Drain air tanks and blow out residual moisture with clean, dry air. In regular operations, onboard air dryers remove moisture in compressed air, but they won’t remove moisture that’s present after the service tanks.
After pneumatic lines are reconnected, install a new or properly serviced air dryer so it can remove any residual moisture from the air inlet.
“Unfortunately, once water or contamination has entered into any of the air brake components – through the exhaust valves, for instance – it’s not possible to completely clear the system without total disassembly,” Szudy said. “Given the importance of a fully functioning system and clean air, it’s necessary to replace all pneumatic air brake components if you find signs of moisture or other contamination, just as you would in the case of salt water submersion.”
The complete guidelines will be posted elsewhere on TruckingInfo.com. Bendix offers information on its Knowledge Dock site (www.knowledge-dock.com ), which has an archive of the Bendix Tech Tips series, as well as videos, blog posts, podcasts, and white papers. and assistance from its service engineers. Users can also or visit www. safertrucks.com/solutions or call 1-800-AIR-BRAKE anytime and get verbal help.