Text and Photos by Agility Fuel Solutions
Much like diesel, cold weather may impact natural-gas-vehicle engine starting and performance. Low fuel pressure and cold air intake into the engine are the most common troubles when temperatures hit below freezing. In extreme cold, three things can happen to a CNG fuel system:
- Fuel lines and filters can freeze
- Fuel and fuel filters can become contaminated
- Pressure regulator diaphragm can freeze
Although no one can control the weather, everyone can take preventative measures to ensure proper CNG vehicle operation, even during the harshest Canadian winters.* Prepare for the worst and expect the best by following Agility’s “Top Ten Wintertime Tips” to keep your CNG fleet running.
Agility’s Top Ten Wintertime Tips to Keep CNG Fleets Running Smoothly
Watch out for poor fuel quality:
Moisture and compressor oil can contaminate the fuel system, as well as engine sensors and other costly components. Consult with your fuel supplier to make sure their station is prepared for winter and their fuel quality meets or exceeds engine manufacturer’s guidelines.
Keep an eye out for problems while fuelling
Ice may prevent the fill nozzle from coupling to the receptacle correctly, causing a leak when re-fuelling. Try clearing the ice by inserting and removing the fill nozzle several times. If this does not fix the problem, the O-rings in the fill receptacle may be frozen. But sometimes this problem “fixes itself.” This is because O-rings expand as temperatures rise, re-sealing the connection. If the leak persists, replace the fill receptacle O-rings. If this does not work, contact the station operator: There may be a problem with the fill nozzle.
Maintain the high pressure fuel filter and drain the low pressure filter
There are typically two filters in a CNG fuel system: The high pressure (HP) fuel filter is the first line of defense in fuel system and engine protection. The HP filter is a coalescing filter, designed to trap particulates as well as remove moisture in the fuel.
If the high pressure filter element is not clean, fuel flow is restricted and moisture and other contaminants can cause damage to the fuel system and engine. Make sure the filter element is properly maintained and replace the filter element according to the recommended intervals. Under the hood, a low pressure filter (sometimes two) further removes contaminants before entering the engine. Drain and replace it per engine manufacturer recommendations.
Watch for frost or ice on the system
Frost or ice forming on fuel-carrying components indicates a leak and decreases fuel flow to the engine. Frost should never be present on the fuel pressure regulator, since it is warmed by engine coolant. If frost is present, check and repair coolant leaks on the hoses to and from the regulator.
Use the right engine oil
Make sure engine oil viscosity is correct for winter temperatures in your area and approved for natural gas service (specification CES20074). A low viscosity engine oil makes engine components move more freely in very cold weather and reduces the load on the engine starter.
Check the engine manufacturer’s recommendations for proper wintertime viscosity and ratings.
Install engine block and battery heaters
Like any vehicle winterizing precaution, an engine block heater helps oil and coolant flowing freely inside the engine. A battery heater helps the lead-acid chemical reaction inside the battery to provide proper voltage and current to operate the engine starter.
Install a winter front to retain heat under the hood
An accessory winter front can help optimize temperatures in the engine bay and protect the vehicle grille and radiator from snow and ice. Some newer vehicles have built-in, temperature-sensing vents in the front grille.
Park vehicles inside – if it’s safe
Since temperatures drop further as the Sun goes down, finding a place out of the weather to park CNG vehicles is suggested. But remember, an enclosed garage must be properly ventilated to prevent gas pockets near the ceiling and heating and lighting must not create a source of ignition. If you are not sure if your facility is configured to park a natural gas vehicle, do not park any natural gas vehicle inside. LNG vehicles should never be parked indoors.
Allow the engine to warm up before driving
Because the CNG fuel pressure regulator relies on hot engine coolant to perform properly, it is best to make sure the engine reaches operating temperature before driving the vehicle during extreme cold weather. Ice and water from condensation in the air path to the engine can affect air-fuel mixtures for the engine and cause poor performance. How do you know if the engine is warm enough? The engine is warm when the vehicle heater is making warm air.
Winterize your CNG system
Agility offers a Winterizing Kit (CNG Fuel Warmer) for certain systems. It uses engine coolant to increase the temperature of the fuel, passively boosting pressure to the engine.
*Please remember: CNG maintenance and repair must be performed by qualified personnel.
Text and Photos by Agility Fuel Solutions