Truck Topics

Engine Focus: Cold Start Tips

With the high price of fuel draining trucking owner-operators' wallets, along with no-idle laws being enacted in so many communities, idling is becoming something to be avoided at all costs.

So, what's the problem? 

You can shut the motor down, kick on the APU or generator and you'll stay warm and have accessory power to boot, right? 

Yes, until you try to start that frigid engine. Starting diesel engines during cold weather can be frustrating if engines are not properly prepared for lower temperatures.

Next to the problems of fuel, winter is probably hardest on the electrical system of your truck. One of the unfortunate ironies of winter is that the cold temperatures are extremely tough on an electrical system that already has a heavy load, operating the lights, the heater and other accessories.

For example, a starter that draws 700-900 amps at 70 degrees will draw 1,800-2,000 amps at winter temperatures.  Batteries that are weak may not crank the starter motor fast enough or long enough to start a cold engine.

As the temperature goes down, so does battery capacity. A battery that has all of its power available at 80 degrees F will have only about 46% available power at 0 degrees F. In addition, the engine will be 2.5 times harder to start at 0 degrees due to thicker oil and resistance to movement of internal moving parts. In effect, an engine is about five times harder to start at 0 degrees F than at 80 degrees F.

A Cold Weather Preparation Checklist:

•  Check the batteries and charging system for cold weather startability.

Your service tech's tester can apply a heavy load for a brief time and use that to calculate the battery’s internal resistance. This works because batteries fail when something prevents the unit from passing enough current. The unit gives a percentage figure that tells how much of the battery’s life is left

Once you know a battery is bad, replace it right way. The more evenly the load is shared among batteries, the longer they will go prior to having trouble, so don’t mix and match. Replace all the batteries in the box unless they are within six months of the same age. Also, stick with the same rating and brand so the performance characteristics are the same. This will pay off in reliability and long life.

Some experts recommend not buying batteries just by “CCA” or Cold Cranking Amps because the batteries with the most CCA often have only half the cycling life.  If you shut down and drain the batteries frequently, another option would be a Group 31, a dual-purpose battery. These can tolerate being almost fully discharged and having it replaced the next day, yet still have good cold cranking power.

Check battery cable terminals for tight, corrosion-free connections.  An electrical test is required for this, because for every 1-volt drop in voltage through the cables, you will lose 30 rpm at the starter.  If you get a voltage drop, the connections should be cleaned with sandpaper or steel wool and reassembled snugly and retested before replacing the cables. Replace battery cables — both positive and ground — that show a voltage drop.

You should have a qualified technician check alternator output to ensure that it's up to spec's. Examine fan belts for cracks, fraying, polishing and check other accessory drive mechanisms, including brackets. Pulleys are harder to spin during engine start-ups in cold temperatures and that puts extra strain on belts. It's a good time to inspect the pulleys as well for proper alignment.

•  Fuel and gelling

Most drivers are familiar with the hazards of fuel gelling in winter temperatures and are well-accustomed to using a variety of anti-gel additives. But what’s going to happen with ultra low sulfur diesel?  Some experts feel there are many variables that haven’t yet been fully explored, and that it will be harder to dissolve the type of paraffin (wax) it contains.

Lubricity will be an issue because it must be added by the downstream suppliers to keep it out of the distribution system. That opens up the chance for error. The fuel is inherently lower in lubricity, and with injection pressures on the rise, lubricity is more important than ever.

In a recent Overdrive magazine article, Jeff Kramer, vice president of sales for Power Service Products, stated that he believes the big ULSD issue is the fact that “blending with No. 1 is going to be obsolete.” Refineries are not going to make a lot of ULSD No. 1, so distributors won’t be able to blend it in with No. 2.

“We’re seeing that ULSD is so different,” Kramer says. “With a shortage of No. 1, truckers need to make sure the fuel is winterized. They need to take the situation into their own hands.” As a result, Kramer maintains that ULSD will need more anti-gel. “Operators will need to be proactive, as much as double treating to properly winterize their fuel in extreme temperatures.”

ULSD will have a lot more wax because of the refining process. So, it will require more anti-gel to keep the wax from causing gellation. there used to be a temperature separation between the cloud point, cold filter plugging point and pour point. Now, they have almost merged. “There’s so much wax that once it hits the cloud point, it’s gelled.”

The cloud point typically occurs slightly below the average temperature for the time of year and location, so in cold snaps, you should be careful to treat aggressively.

Every fuel batch is different.  There are winter and summer blends. The winter blends are created by taking some of the waxes out. Some refiners do everything right. But not all do.

In those cases, you might need anti-gel additives. Anti-gel puts a charge on the tiny wax molecules so they repel one another, which stops the wax from globbing together. “This prevents gelling from occurring for another 25-30 degrees F. below the untreated fuel,” Kramer explains.

Current anti-gels will work, and treatment procedures will be the more cautious. That would come down to using a better fuel/water separator. Plus, it’s important to use a dispersant, anti-ice or a water absorber.

•  Lubrication

Being a knowledgeable, professional driver, you already know about multiviscosity/multigrade oils, but did you know...?

The multigrade oils are used because the engine can turn over easier when cold and because viscosity doesn't fluctuate as much as with straight grades.

Take 15W-40, for example. The number 15 indicates how easily an oil will pour in extreme cold - the lower the number, the better. There are 6 different winter classifications - 0, 5,1 0, 15, 20 and 25.  The letter W stands for winter.

The second number indicates how well oil is able to lubricate the motor at higher temperatures. Those classifications are 20, 30, 40, 50 and 60.

Check your transmission and differential fluids to determine if they match cold weather specs. Regular chassis and driveline greasing are important in winter - for lubrication, of course, and to help protect those components from slush and de-icing chemicals.

If you operate in really bitter weather and must start the engine on subzero mornings, you might consider synthetic oils for both the engine and the driveline components. Some experts contend that they offer less rolling resistance, increased

Lubricity and longer drain intervals. They also claim a 2% increase in fuel mileage.

•  Cooling System

We'll assume that all of the belts have been checked during the electrical system examination, so turn your attention to the hoses and clamps. The coolant hose is a vital, yet sometimes overlooked component in the cooling system. In addition to absorbing the vibration that is transmitted from the engine to the radiator, the hoses carry coolant to and from the radiator. Without flexible rubber hoses, the vibration may break off at the inlet or outlet connections of the radiator.

Hoses are expected to carry more than 7,000 gallons of hot coolant per hour, while they are exposed to under-hood temperatures in excess of 275 degrees F. and under pressure of 15 to 18 psi.

Inspect all hose connections for leaks, cracks and soft spots. If a hose exhibits any of those symptoms, replace it. Maintenance experts recommend the use of long-life silicone hoses, which have become an industry standard.

It might be good time to replace any suspect hose clamps at this point.

Recommended are the stainless steel types with screw securement. A rule of thumb would be to not over-tighten clamps, rather, tighten them until the hose just starts to bulge. Run the engine to operating temperature and retighten the clamps.

Thermostat housings can become badly corroded with age and may not seal properly when the new hose is installed. If the housing is rough or pitted, replace it.

A 50-50 mix of ethylene glycol antifreeze and water will protect against freezing down to minus 34 degrees Fahrenheit. If you need greater low-temp protection, a higher percentage of antifreeze is called for, but the experts say to avoid concentrations greater than 60/40.

The ideal concentration is 50/50 unless you live in an area where the level of protection 50/50 provides, (-34 degrees F.) is not adequate. Up to 60 percent concentration can be used, which protects down to -65 degrees. To increase antifreeze level, drain some coolant and add straight antifreeze. To decrease, drain some coolant and add de-ionized water or tap water whose mineral concentration meets the engine maker’s standards.

Truck engines are designed with an operating temperature range of around 195 to 200 degrees Fahrenheit regardless of ambient temperature and that's the job of the fan drive and thermostat.

Your mechanic should ensure that the thermostat operates properly. Thermostats often fail in the open position, so the engine will require a longer warm up time and may run cooler if not under load.

Coolant filters should be checked and cleansed of various contaminants. Many filters also gradually release Supplemental Coolant Additives (SCA's), which are corrosion-fighting chemicals. If your mechanic discovers that the SCAs are gone, the filter should be changed.

• Engine Heaters

Though not truly part of the electrical/starting system, engine heaters can ease the strain on the batteries and other components in cold-start situations, and at the same time, reduce metal wear due to cold, thick oil.

One method to keep the engine warm is by the use of a coolant heater, which can be a remote-mounted tank (shore powered or diesel-powered) or an immersion-block design. With both types, the engine's coolant is heated to around 160 degrees and circulated through the engine block. For example, a 17,000-Btu/hr-coolant heater will raise a Class 8's engine temperature 100 degrees above the outside temperature in about an hour.

As the heater warms the coolant, the oil on the pistons and bearings will also warm up. This will allow much faster cranking, which decreases the load on your battery and starter. The faster cranking and warmer cylinders will make the air much hotter during compression, resulting in an instant start.

Remember, after starting the engine on a cold day, allow the engine to warm up a few minutes before putting the engine under load. Proper engine operation temperatures assure more efficient fuel combustion and may prevent damage to cold engine parts. Engine oil flows more readily at operating temperatures and allows proper lubrication of upper engine parts and areas.