Tech Corner: Cold Weather Diesel Engine Prep

It’s coming. We may not want to talk about it, but winter is on its way. And for all of us in the automotive world, that means it’s time to start prepping. Being prepared for winter is important for any car owner, but especially so for diesel engine owners. Every engine operates differently in cold weather but diesels, in particular, are subjected to some obstacles that can take owners by surprise. Considering diesel engines are becoming more and more popular power plant options, we figure now is a good time to talk about what owners should consider as Old Man Winter approaches.

Preventing Fuel Gelling

Diesel fuel has many different properties than conventional gasoline. This means it will naturally have very different characteristics. For some insight on the matter we reached out to our friend Brian Toole, a diesel engine mechanic at Prime Inc. “The most common [winter issue] is when an owner’s fuel gels up because they had untreated fuel in a very cold climate. All of the guys that travel up north for a few days during the cold months with southern fuel end up gelling up.”

Understanding why diesel fuel gels up is your first step in preventing the issue. Diesel fuel contains paraffin. This wax is used to raise the British Thermal Units (BTU) value—a measure of the energy stored in fuel. The more paraffin, the higher the value. But when temperatures drop below 32°F, paraffin will begin to crystalize, which can spell trouble for your diesel engine. At this temperature, the fuel will be visibly cloudy. And if that fuel reaches 10-15°F it will become gel like. This, in turn, can clog fuel lines and filters, preventing the vehicle from starting. As Toole mentioned, treatments in the fuel itself can prevent this from happening. And in the case that you’re using untreated fuel, you can treat it yourself with additives like those produced by FuelOx.

Checking Glow Plugs

Another thing diesel engine owners should watch for are bad glow plugs. Diesel engines use thermal plugs to raise the temperature of the combustion chamber to aid combustion of the fuel as it is compressed during starting. In cold weather, the plugs will have to work harder and may not be able to raise the necessary temperature for starting.

“If you’re having that issue, you put a hurting on your batteries and starter from the excessive cranking trying to get it started,” says Toole. So, during the winter season it’s a good idea to make sure that those plugs are up to par.

Changing the Fuel Filter

Another important aspect to address is the fuel filter. Many diesel engine mechanics will tell you that keeping up with the fuel filter is important year-round. But during the winter, you should take extra care to make sure it’s in good working order.

Along with holding bits of debris and dirt, fuel filters may contain some water. This water can then freeze, keeping the thicker fuel from flowing through. This will starve the engine of the amount of fuel it needs to start, and you’re right back to beating on the batteries and starter.

Batteries and Block Heaters

Two more tips for diesel truck owners in the winter months are small but important. First and foremost, make sure your batteries are in good shape. During cold weather, old batteries can lose their charge overnight. So, if yours are due for a change, do yourself a favor and replace them before winter kills them. Secondly, use that nifty block heater that came with your pickup. Simply plug it in when the truck sits to help with the cold starting process. And keep a long extension cord on hand. You never know how far an outlet might be from your very cold parking spot.

Winter is coming—and it doesn’t take that much to be prepared. Even if you live in an area with a mild climate, freak occurrences happen. All you need is one nasty cold front to blow through with temperatures low enough to leave you stranded. So take care of that diesel engine because when the snow starts falling, it’ll surely take care of you.

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