Great Care Must Be Taken When Installing Spin-On Fuel Filters
By John Gaither, P.E.

When the time comes to change the spin-on fuel filter on a heavy-duty diesel engine, there is one extremely important thing to remember: the absolute worst thing an operator can do is run a diesel engine out of fuel. That is why following the proper procedures for spin-on fuel filter installation is imperative.

Maintenance technicians should follow these six basic steps:

  1. Remove the old filter;
  2. Clean the base;
  3. Lubricate the new filter gasket;
  4. Pre-fill the new filter with clean diesel fuel;
  5. Install the new filter; and
  6. Tighten the new filter per the proper amount of turns that are noted on the label, taking care not to over-tighten. If the filter is unable to be tightened by hand, use the appropriate wrench.

The trickiest step is No. 4, filling the new filter. With a diesel engine, the fuel filter needs to be filled with diesel fuel before it is installed. If it isn’t, the vehicle will not start. It is recommended that the center of the filter be plugged before diesel fuel is poured into the inlet holes. Only then should the filter be installed on the vehicle. Some newer models of diesel fuel filters feature a plastic plug that helps simplify the filling process.

Also, remember that it is important that only clean diesel fuel be poured into the new filter. In conjunction with this step, all air must be bled from the fueling system. This is usually accomplished via a vent plug or valve located above the fuel filter, or with an electric fuel pump. Some systems will provide a manual pump that can be used to prime the system. If all of the air is not removed from the system, the vehicle may start, but it will probably run rough for 30 seconds or so before returning to normal operation, and in extreme circumstances, it may not start at all.

One other area of concern is the presence of water, which can enter bulk fuel tanks via condensation, carry-over from fuel-distribution systems, and leakage through the fill cap, spill containment valve or piping—before finding its way to the vehicle’s fueling system. If water is allowed to enter the fueling system on diesel vehicles, many problems may occur, such as lower power output, engine shutdown, and fuel pump and injector wear and/or damage.

For many applications, Luber-finer addresses the strict requirements of spin-on fuel filter changeouts with its TotalTec Heavy-Duty Fuel Filters. The fuel filters feature an advanced design that eliminates the need for a plastic bowl add-on, along with the worry of fuel/water separation and fuel-filter maintenance. They have a larger filtering area for more efficient, longer-lasting filtration, along with durable, leak-proof, all-metal housing construction that withstands high pulse fatigue and reduces the risk of leakage due to cracks and breakage. The absence of a plastic bowl also decreases maintenance time and the mess associated with changing plastic bowl fuel filters.

For additional maintenance tips from Luber-finer, visit

Gaither is the director of heavy-duty engineering for Luber-finer, which is part of FRAM Filtration.