You mean I need to maintain this?

Fuel filter maintenance is more important today, than any time in the past given the common rail design and tight tolerances.

See below data from Cummins.

To meet today’s stringent emission regulations, fuel system injection pressures are extremely high (up to 37,000 PSI) to achieve better and cleaner combustion utilizing multiple injections resulting in optimal combustion and better fuel economy. As a consequence, clearances between the moving parts and the higher number of very small nozzle holes found in injectors all need improved protection from erosion. 50% of the worldwide diesel fuel supply does not meet OEM specifications for cleanliness; particles greater than 4 microns in size are known to cause wear to these sensitive systems. By way of calibration, human hair is typically 50 to 70 microns in diameter, a red blood cell is 8 microns and bacteria are typically 2 microns. The smallest particle which can be seen by the human eye without any magnification is 40 microns! To meet these demanding requirements, much finer filtration requires special media.

• Dirt and sediment – will result in blockage of the filter and increased wear within the fuel system.

• Water – is the greatest concern because it is the most common. It can be introduced into the fuel during the refueling process: through condensation inside the fuel storage tank, and or due to poor house-keeping practices. The effects of water in diesel fuel can be serious, causing injector tips to blow off, corrosion and reduced fuel lubricity, resulting in premature wear to pumps and injectors.

• Organic contaminants – Asphaltines and paraffin wax, which are residual components from the refining process, will block screens, strainers, filters and even hoses.

Refer to the graphic for the specifications of a Davco 245, as an example. The Micron value is 8. Since the smallest particle to be seen by the human eye is 40, means you can’t tell when it’s time to change the filter by observation. The Restriction filter has to be used to determine when the filter requires changing. Some manufactures require changing every 25K miles. Notice the water removal difference in NEW vs END OF LIFE elements (same chart), which is another reason to change filters on a regular basis.

Given all this, it’s hugely important today that when a filter is changed, that the tech not fill the container with fuel from any external source since contamination could easily be introduced into the clean side of the filter causing the issues noted above. The proper way to change filters is to drain the fuel, replace the element, and use the manual or electric engine pump to pull fuel from the tank/s, ensuring that all the fuel is properly filtered.

BRRRR.. Truck won't start

In cold weather, there are a number of methods to warm the fuel to help eliminate clouding/gelling. Cloud point refers to the tendency of a fuel to form wax crystals as temperature drops. These crystals (paraffin/wax) can clog the system, not allowing the engine to start.

Heated fuel/water separators: These filters come with a variety of options. 12V (battery DC when the key is turned on), 120V AC (Shore power, plugged in hopefully along with the engine 120V block heater) Return fuel (high temp low volume routed through the fuel filter head as the fuel is returned to the tank), and or engine coolant (higher volume lower temp, routed from the engine block to the radiator, hoping again that the engine block was plugged in).

Fuel tank heat: Artic fox is one that is offered by some OEs. These products run engine coolant through a pipe that transfers coolant heat to the fuel. They only function when the engine is running, so plugging in the engine block heater again is required.

Fuel line heat: Operates on 12V (key on) and warms the fuel from the tank to the filter.

Any combination of these will work, depending on the ambient temps.

If a fuel cooler (for high temps) is spec’d or required, they are usually not controlled by a thermostat, therefore operate all the time, yes even in the cold. I would highly recommend a manual diversion valve, or a system to eliminate air flow over the fins for cold weather operation.

By the way… Diesel is dyed in order to denote if it has paid road tax or not. On-road diesel in the United States usually has a light green tint to it. Off-road diesel has a red dye to denote it has not paid road taxes as required by all states and the Federal government.

Beauty is in the eye of the beholder

Trailer gap was never even a consideration back in the 90’s. As a matter of fact, it was another 10 years beyond that decade when things began to change. Back in the day, you could NOT talk a customer into ground dump exhaust… everything was independent, with pipes vertical behind the cab. This was “The Look”.... What changed?

Price of fuel, EPA standards, Model restrictions. Well, these are somewhat related as OEs funneled development efforts to align with the first two. You see, vertical exhaust stacks add at least 20 inches to the trailer gap. This is what is required to clear trailer swing. Trailer gap is the measurement from the back of the cab or sleeper to the forward face of the trailer.

If you have side extenders on the chassis, or if you have a reefer unit on the trailer, these items are omitted from the measurement. Studies have shown that the more you can close this gap; the less resistance will be encountered as air flow moves over the chassis and trailer as a unit. Larger gaps permit air to flow between the chassis and trailer, creating a vortex resulting in drag. This area accounts for 25% of the total combination drag. And the best measurement for minimizing this loss is 42-inches maximum.

What you should know is how the dimension, and associated lack of efficiency, translates to operational costs. Lowering the gap by 10 inches provides a 0.5-1% increase in fuel efficiency. So, if we apply that to the independent exhaust that was popular 15-20 years ago, we see a loss of 1-2% fuel efficiency.

Today the industry is ALL about efficiencies. The past two Greenhouse Gas (GHG) emission levels have focused on this. As chassis styling changes, and powertrain evolves, it makes sense that OE product offerings align with vision of efficiency. We are all in this together. And the results are impressive, fuel economy is at an all time high, which lowers operation cost and provides increased revenue for customers.

Of course, you see many new trucks with exaggerated wheelbases, “The Look” for certain applications. It is doable. You can, on some models, still get vertical tailpipes behind the sleeper. And truly, if your customer wants the vehicle stretched out, fuel efficiency is less important, and the vertical stacks complete the look. In these cases, the benefits of a 42-inch gap is not worth the debate.