Catching Cold

It’s ironic that the No. 1 source of truck breakdowns in winter is the cooling system. Cold temperatures magnify problems like worn belts and hoses, and thus the need for vigilant maintenance. That’s why it pays to ready your truck for winter now, before the bad weather sets in. Here’s a list of concerns:

1. Cooling System. Examine belts for cracks, fraying, polishing, and any other obvious surface defects. Check tension if the belts don’t have automatic tensioners; if they do, verify that the tensioner is applying the right sort of load.

Next, check your hose connections. Tight clamps, or maybe the wrong kind, can easily cut into the hose surface. If a hose is damaged, replace it and splurge-buy constant-torque clamps to spread the load over the hose surface. Leaks will usually show with traces of crystallized antifreeze on the radiator tank tubes, water pump, etc., where the hose attaches.

At the top of the cooling system, check the radiator cap for cracks in the brass seal plate or the rubber seal. Also look for corrosion at the top of the cap around the rivet. If you see evidence of these problems, replace the cap with a new one rated for the recommended system pressure.

2. Coolant Chemistry. Sample the coolant from the surge tank or the radiator and check it for freeze-point and nitrite additive levels. The most accurate method is using an optical refractometer to check the freeze point, but dual-purpose test strips can be also be used. Cooling system experts caution against “ball testers,” as they are inaccurate.

If the freeze point is off the ideal -34° F (which is provided by a 50/50 mix of antifreeze and water), adjust it (a 10° F spread is usually allowable). If the mixture is off, calculate the amount of antifreeze to be added using volume/temperature charts available from coolant suppliers.

Testing strips will show the amount of nitrite in the coolant, indicated in parts per million. A chart on the test strip bottle describes the correct amount needed, ideally from 1200 to 3000 ppm. Follow the chart when making adjustments. To correct additive levels, use either a liquid supplemental coolant additive such as Pencool 3000; a standard coolant filter; or an extended life coolant filter that features a controlled-release type of additive package such as the Baldwin BTE5200.

3. Fuel System. Check fuel tanks for water sitting at the bottom that could be drawn into the lines and filters, freezing there and causing the engine to falter and then just stop. Use a brazing rod: put a water paste such as Kolor Kut on the end of the rod, stick it into the fuel tank until it hits bottom, and hold it there for about 20 seconds. Remove it and see if the paste has turned bright red (the level of red tells how much water is in the tank).

Another clue to the presence of water and bacteria is odor. If the fuel tank smells like rancid butter, bacteria is present. The same is true of a stinking fuel filter. In preparing for winter emergencies, buy a few containers of fuel conditioner and also an emergency product that will thaw gelled fuel. And keep them in the truck.

It may be stating the obvious, but don’t buy a truck without having a fuel/water separator installed. If you have one already, make sure it works. If the water sump on the separator is getting full, drain it. If it’s supposed to automatically expel water, but doesn’t, get it fixed or replace it.

4. Heaters. Fuel heaters that raise the temperature of the diesel fuel between the tank and the filters to prevent wax and gelling can be electric or may use engine coolant. Block heaters make sense when the truck is parked in the open for long periods. When starting the engine, most engine makers like to see a minimum temperature. Typical is Mack Trucks’ recommendation of 170° F before moving off.

5. Overcooling Protection. The optimal engine temperature avoids damage from carbon and varnish buildup on the valve stems and prevents oil contamination from unburned combustion products. But the blast of extra-cold air through the radiator at highway speeds can overcool an engine. Winterfronts or even belly tarps help, but note that some truckmakers allow only certain winterfronts because over-restricted flow can raise temperatures in the charge-air cooler. This leads to high exhaust temperatures, power loss, excessive fan cycling, and potential engine damage.

Another caution: open your winterfront symmetrically so the engine is cooled evenly from side to side. Offset or unbalanced openings also cause fan flexing as blades run in and out of the air flow, risking fatigue damage.

Note that extended idling overcools an engine year-round, but it’s most troublesome in winter. If you have to idle, avoid overcooling by running the engine at a high idle of 1200 rpm.

6. Electrical System. In winter, batteries must generate cranking amps at low temperatures, which reduces their output; consider a battery heater wired into the block-heater circuit. Electrical loads are higher in the winter, with lights, wipers, and such working more often. Have the alternator output verified and the battery condition checked by a suitably equipped shop. Also check to see that your wiring is correctly routed and supported against the frame. Snow and ice on hanging wiring can lead to failures and even fires.

7. Air Drying. Air dryers are more effective than the old alcohol evaporator in delivering clean, dry compressed air, if only because they’ll remove all manner of contaminants-as well as moisture-before the air reaches the wet (supply) tank. But their filters have a finite service life, usually between two and three-and-a-half years. If water shows up when you attempt to drain the wet tank, the filter’s done and your dryer is no longer fully effective. Some dryers have a heater to keep air lines free of ice, usually activating when temperatures fall below 45º F (7º C).

Don’t forget that the various connections in the air system must be leak-free if you’re to keep water and other contaminants out.

And, as if we need to mention it, if the air tanks aren’t fully drained down to zero pressure on a daily basis, oil and water will accumulate. Havoc will result, and you’ll be left feeling steamed-out in the cold.