Signs of Air in Your Diesel Fuel and Airlock Symptoms
If you own or operate a heavy truck, you know your engine must run smoothly and efficiently. However, an issue that disrupts the smooth operation of many engines is the presence of air in the fuel line, which causes several problems, including a condition known as an airlock.
To help you avoid this problem, we will review the signs you have air in your diesel fuel lines and the problems caused, including airlock, and suggest several ways to address those issues.
Signs of Airlock and Its Causes
Airlocks occur when air enters your fuel system and keeps the diesel fuel from reaching the injectors. Unable to pass fuel through the bubble stuck in your system, typical symptoms include difficulty starting the engine, reduced engine power after starting, and, in severe cases, the inability to start the engine.
Airlock can occur due to your engine running out of fuel, leaks in your fuel lines, air bubbles in your fuel, or following a fuel filter change when the fuel filter does not get primed correctly. Running out of fuel will almost certainly result in an airlock, but that issue is resolved by not running out of fuel. Leaks in your fuel lines may cause sporadic airlocks and reduced engine power, a problem that requires you to repair the problem parts.
Airlocks due to air in the fuel and improper filter-changing procedures can be addressed by bleeding and properly priming the fuel lines, which can be time-consuming. However, as shown below, these airlocks are either prevented or more easily resolved in engines with AirDog® fuel systems.
Understanding Air in Diesel Fuel
As your truck runs down the road, the diesel fuel in the tank sloshes around, mixing tiny air bubbles into the fuel. Contrary to popular belief, those air bubbles do not simply float up and out of the fuel. Instead, many air bubbles remain in your fuel and enter the fuel line, eventually reaching the engine.
Besides air in your diesel fuel, moisture also enters your fuel due to improperly sealed storage tanks and condensation in the fuel tank stemming from changes in outside air temperature. Both situations lead to less efficient fuel combustion and potential engine damage.
The Problem with Standard Fuel Filters
Although standard fuel filters can effectively trap solid contaminants, they do not remove air and moisture from diesel fuel, so they are ineffective at removing the air bubbles that can cause airlock. The standard fuel filter and fuel system are also susceptible to allowing large amounts of air to enter during a fuel filter change. This situation occurs because the fuel filter replacing the old filter needs to be filled with fuel and later topped off to limit the air introduced into the fuel lines.
Following a fuel filter change, those with airlock symptoms must bleed the lines and manually prime the fuel system or use the ignition to prime the fuel system (on some engines). Each process requires time and labor; time, like labor, is money.
The Solution: AirDog® Heavy Duty Diesel Fuel Systems
The primary purpose of AirDog® fuel systems is not to prevent or minimize airlock problems, but they are very effective at addressing both issues. The primary goal and benefit of AirDog® fuel systems is to remove air and water from diesel fuel before it enters your engine, so let’s look at how the AirDog® fuel system works generally and eliminates airlocks.
The AirDog® fuel system’s first step is to send the fuel through a water separator that eliminates moisture and particulates down to 2 microns. Second, the fuel passes through the AirDog® Fuel Preporator, which removes air from the fuel. Third, fuel pumps integrated into the AirDog® fuel system send the pure diesel fuel to the engine at a regulated positive pressure. The integrated pumps also reduce the opportunity for air to enter the system by keeping vapors out and reducing vapor-causing cavitation.
The advantages of the AirDog® fuel system become clearer when you consider that we recommend carrying extra filters in the truck so you can change the filters on the road if needed. As with conventional fuel filters, you should perform the procedure safely with a container available to catch spilled fuel or residue. Still, the process is as simple as removing both filters and priming the water separator filter with fuel before screwing it on. While the water separator needs priming, the AirDog® fuel filter does not. You can screw it on without being primed. After everything is in place, turn your key to “On” (without starting the engine) and allow the AirDog® pump to run for 30 seconds. That step pumps fuel through the system, priming it to ensure the fuel line does not have air pockets.
The ease of this process and its ability to eliminate airlock issues resulting from changing fuel filters demonstrates yet another advantage of AirDog® fuel systems and their integrated pumps. AirDog® systems are so forgiving of procedural errors that allow air into the fuel system that we sometimes say that AirDog® fuel systems can handle air introduced by error.
While AirDog® fuel systems virtually eliminate airlock issues for properly operating engines, those who suspect fuel system leaks or cracks are causing problems should address those issues promptly to prevent further damage and maintain a healthy fuel system.
The Bottom Line
Air and water in diesel fuel reduce engine performance and fuel economy, damaging critical engine parts over time. AirDog® fuel systems eliminate air and moisture before the fuel enters your engine, allowing you to achieve peak engine performance. An additional benefit of AirDog® fuel filter systems is the same design that eliminates air from diesel fuel, and the integrated pumps that push fuel through the system also eliminate airlocks caused by air in the fuel and improper filter-changing procedures.
AirDog® fuel systems optimize your engine performance when rolling down the road and provide an extra safety measure following maintenance, ensuring your engine starts properly without the problems caused by airlocks. Check out AirDog®’s Champ, Champ II, and the AirDog® FPII.
