Location, Location

Low temperatures tend to swell the crud and water that gets into fuel tanks, and as this stuff is drawn into lines, clogs can occur. If contaminants make it through the inlet line, filter elements can become plugged, and even the best diesel engine will stall and grind to a halt.

Fuel-water separators and heaters can do a lot to alleviate such problems. Here are some simple tips to make sure yours are ready for the cold months ahead.

Fishing upstream. When placed upstream of the standard engine-mounted filters, the separator becomes the primary filter and spin-ons act like secondary filters. Alternatively, an element-type separator can replace a spin-on element, but filtration capabilities and restriction should be within the engine maker’s guidelines.

Many trucks have a transfer pump that moves fuel from the saddle tanks to the engine’s fuel system. The pump can whip free water into emulsified form, making it tougher to remove. So it’s better to install the separator upstream of the transfer pump to catch any free water before the transfer pump can emulsify it into the fuel. To avoid air-locking problems, keep the separator below the level of the engine’s fuel pump. The closer it is to the engine the better, because engine heat will help keep fuel flowing and water from freezing in the separator’s water sump.

If the truck already has a separator, make sure it works. If the sump on the separator is getting full, drain it. If it’s supposed to automatically expel water but doesn’t, get the device fixed or replace it.

Pull the plug. A simpler idea is to remove the contaminants at their source on the truck: the saddle tanks. Fall is an excellent time to drain the tanks of the dirt and water accumulated during summer’s heat. Fortunately, most of it settles to the bottom of the tank, making the draining process easier. It’s good practice in cold weather to check filter separators at the end of a shift or the end of a day, when the fuel is hot and water is still liquid. It’s no use checking a filter separator in the morning when the truck and fuel system have chilled below freezing. you’re at it, inspect all fuel lines and fittings for integrity. If anything is aged or damaged, fix or replace it.