Weathertight Cabs

Nov. 1, 1997
Don't forget the driver when winterizing trucks. When most fleet operators think about winterizing their trucks, they think about the engine. Common practice is to check antifreeze, hoses, and belts, change the oil, and refresh the level of supplemental coolant additives. Few, however, give any thought to the cab and the driver. But wages, benefits, and associated driver costs are usually a fleet's

Don't forget the driver when winterizing trucks. When most fleet operators think about winterizing their trucks, they think about the engine. Common practice is to check antifreeze, hoses, and belts, change the oil, and refresh the level of supplemental coolant additives. Few, however, give any thought to the cab and the driver. But wages, benefits, and associated driver costs are usually a fleet's second largest operating expense, right after fuel. Not only can winter problems affect drivers themselves in terms of safety and comfort, they can also affect a fleet's ability to recruit and retain drivers.

Since drivers spend many hours in their cabs, the cabs need to be as weatherproof as a home. If the trucks are new, there is probably not much work needed to maintain comfort, especially if they have optional "arctic packages." But once trucks are a few years old, they start to need care and attention.

There are several approaches to winterizing cabs. The most common, but not the most effective, is to "fix whatever goes wrong." A better approach is to think of the cab as a comfort system and to inspect its components systematically. Preventive maintenance can keep little annoyances from becoming big headaches.

A great deal of a driver's comfort level is related to temperature, so it's important to maintain the right temperature at the right place in the truck. Drivers need their feet warmer than their torsos, especially when they drive, to keep them comfortable and alert.

Cab temperature may average 70 deg, but if that's obtained with a blast of 85 deg air at a driver's face and chest, and 55 deg at his feet and ankles, the driver will be miserable. This is not unusual because in winter a driver's upper body and head will receive extra heat when he or she is driving into the midmorning or midafternoon sun. If the doors are missing weathersealing, the driver may feel drafts by his feet, and if the heater core is blocked by an accumulation of dirt, etc., the cab in general may be uncomfortably cold.

It's important to develop a procedure, and inspect things in an orderly manner. The cab can be checked by going around from left to right and floor to roof, or by checking each functional system, one at a time. Looking at systems may mean your technicians will have to retrace their steps, but system-by-system checking is effective.

Drafts make cabs uncomfortable, so start with them. Drafts occur because seals deteriorate over time, stiffen, or crack. If they're not compliant, they don't stop the wind. Drafts also occur when vibration and road shock loosen panels, floorboards, and fittings. Hinges go out of adjustment, doors don't shut right, and eventually drafts become noticeable.

Drivers don't have to be encouraged to report winter problems, especially drafts. But it's hard for mechanics to check for the exact source of drafts and air leaks when a truck is sitting still. Even running at 55 mph with a 20-mph tail wind, they may still not be apparent. Heading into the wind, however, your mechanics will find leaks more easily. They need to be aware of what they're feeling, as well as what they're hearing. Any whistling or whooshing sounds should be checked. Have the mechanics note where they seem to come from and check their findings against the drivers' reports.

Draft elimination is fairly easy once you've located the source. Tighten what needs tightening. Replace any worn hinge pins or bushings, missing seals, control cable grommets, or weatherstripping. Don't forget to inspect heater doors and the hot air distribution system because cold air could be coming in through the heater system itself. And the truck's doors aren't the only things that can shake loose. If your trucks have cowl vents, check them for free operation and for tight seals. Vent windows and side windows often leak, so check them too.

Molded seals that fit specific trucks are available at OEM dealers. Closed cell foam weatherstripping is less expensive and can often be as effective. It is readily available at parts jobbers.

Once obvious drafts have been eliminated and the cab is "tight," make sure heater and defroster systems are functioning properly. The heat exchanger, which is located in a housing behind the dashboard, is the heart of the heater. It works like a miniature radiator, transferring heat from the engine coolant to the air blown over it. The warmed air travels through ductwork to the driver's feet or to the windshield for defrosting purposes. But before the heat exchanger can do its job, it must have a reliable flow of hot coolant. To ensure that this is the case, check coolant flow through the heater hoses.

Next, be sure the heater controls move freely. If anything needs tightening or lubricating, do it. White grease is easy to apply and stays in place, but before applying it make sure the linkage and hinges need lubrication. Keep in mind that petroleum products can ruin self-lubricating plastic bushings.

Fuel-fired auxiliary heaters are becoming more popular every year. In fact, there are now at least five companies supplying the market. While newer units don't need much maintenance, all fuel-fired heaters should be checked when preparing the vehicle for winter weather. Unless the heater is a newer model with a ceramic ignition, it's a good idea to replace glow plugs or re-gap igniters to prevent ignition failure.

Make sure the fuel lines are clear and the wiring is tight and corrosion-free. And don't forget to change the fuel filter. After checking the ducts on an air heater, or the hoses and clamps on a coolant heater, test the device to make sure the sensors and safety devices work.

Cab wiring is important, especially in winter when batteries lose efficiency. Current drain that would go unnoticed in summer could keep your truck from starting in winter. Give all wiring a quick visual check for chafing, loose grounds and connectors, or corrosion. Then coat any exposed terminals with petroleum jelly or electrical protective compounds. If your trucks have motorized or heated mirrors, check the wiring that leads to the mirror heads because poor connections will also cause them to fail.

That takes care of the truck cab, but not its occupant. If there's any risk of being caught in a blizzard, equip trucks with winter emergency kits. Basic equipment should include an aluminized mylar blanket and a supply of chemically reactive heater packs. In case the truck's heater fails or an engine blows, the driver will need a source of heat. A candle can help warm a truck, but if drivers run an open flame, caution them to crack a window for ventilation. The emergency kit should also include warm clothes and extra food and water. If space is a problem, use highly nutritious hiking and camping foods, which are freeze-dried and very compact.

With a little added attention to winterizing cabs, you can increase driver satisfaction greatly. If you eliminate drafts, make sure heaters will be ready when they're needed, ensure that the electrical system is reliable, and remember the driver's personal needs, drivers can face the worst that winter has to offer with confidence in their equipment and your concern for their well-being.

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