In a previous article, Diesel Emissions Control: Part 2 - Truck Maintenance Downsides, we provide an introduction to efficient system maintenance tips. However, it is worthwhile expanding in detail as being proactive with engine maintenance yields distinct benefits to your business, including improving your engine's lifespan and performance, minimizing the risk of a costly and dangerous major breakdown, and ultimately getting the most return on investment.

This is a two-part article on the fine points of engine maintenance. The sections in the articles include fuel filtration, the electrical system, adjusting your overheads, and the cooling system and are organized by frequency of how often maintenance is needed. Part one will cover maintenance for fuel filtration and the electrical system,  and part two will cover adjusting your overheads and diesel cooling systems.

Fuel filtration

What area of industry sees the tightest standards of all for the clearance between moving parts? Is it NASA and the space program? No! It's diesel injection equipment. And the performance of devices with tight clearances will deteriorate rapidly if dirt causes the surfaces to be scored. As a result, fuel filtration has always been a major concern on diesel trucks, and filter specifications get tighter and tighter.

Here are the top 4 things to keep in mind -

1. Adhere to Filter Micron Ratings

While unit injectors had tight-fitting plungers sliding up and down inside the injector body, today's common-rail systems have pumps with extremely tight tolerances in order to produce extreme pressures without wasted energy or poor metering of fuel, as well as tight-fitting needle valves inside the injection valves that sit just above the combustion chambers.

These valves don't just meter each shot of fuel for each time their cylinder fires, they divide that shot into several separate injections, some of them extremely short. For example, when the engine is under load, a tiny shot of fuel goes in early, well before the main injection starts, in order to speed ignition. If that shot is too big or too small the engine will get noisy, or may perform poorly. In turn, system tolerances and the micron ratings of your filters have gotten extremely tight. Adhering to these ratings will help ensure long life and good performance from these hard-working, precision parts. When you replace your filters, make sure to use filters that fully meet engine maker specifications.

Your system has a primary filter between the tanks and the fuel pump on the engine. A secondary filter is normally much finer and filters the fuel just before it enters the injection pump. The goal is to provide easier flow through the primary filter because it runs under a slight vacuum. The flow there is provided only via the pressure of the outside air on the fuel in the tank. While any filter will flow fuel easily at the beginning, a finer filter will clog more quickly. Stopping most of the larger particles in the primary filter helps to keep the secondary filter from developing too high a pressure drop.

2. Change fuel filters at oil change intervals

Filters are rated by microns, which refers to the diameter of the particles it will capture. But, there's a catch: Filters don't catch 100% of particles, they catch a varying percentage depending on the size. Your engine's specifications for filtration likely will give a number like 99% at 3 microns. The percentage may also be expressed as a Beta ratio (β). A Beta ratio of 10 means 90% and one of 100 means 99%. Thus, 1,000 means 99.9%. Make sure the filter you use in each position meets factory recommendations.

Change your filters at the interval in miles recommended by the manufacturer of the engine, typically at the change interval for the oil and oil filter for your type of service. Do all you can to make sure you are using approved filters, for example by using recommended part numbers and brands, if provided.

Purchasing from a top-quality supplier and using the filters they recommend for your specific engine, is another way to go. Many engine makers have their own brand.

Diesel fuel is close to the density of water, and for that reason water content in diesel fuel is a problem. The best primary filters come in the form of fuel/water separators. While properly treated spin-on filters will remove water, a larger separator will do a better job and hold more water before you run into restriction problems. You'd be smart to have a good fuel/water separator installed if there is not one already on your tractor. Make sure to drain water and change the filter or have this work done at recommended intervals.

You can have fuel filters changed when you have an oil change done at a service outlet. If you choose to replace them yourself, or need to replace them because of clogging by dirty fuel, you'll need to do the job right or risk a no-start. This advice is also helpful if you should run out of fuel.

3. Supply clean fuel

You'll need to have a supply of clean fuel available. Fill the new filter to the top with clean fuel before installing it. Many engines have a manual pump that is used to pressurize the system after a filter change. You may simply have to unscrew a collar that holds the plunger in place and pump the plunger up and down to pressurize the system. You may also need to uncap and/or open a bleed valve for air to be expelled. Some engines may have an electric pump operated by a switch on the dash. Use the pump to make sure the system is pressurized and full, and then start the engine and operate it until it runs smoothly before proceeding to the secondary filter.

Follow the same procedure for the secondary filter, filling it all the way before installation. Also follow all manufacturer instructions as to lubricating the seal on the new filters, usually with clean diesel fuel or engine oil. For spin-on filters, turn the can the number of degrees of rotation, say 3/4 of a turn, from the point where the gasket contacts the sealing surface on the filter base, to tighten it. Normally, the secondary side of the system will be filled and pressurized by the fuel pump on the engine‚ if you have filled the new filter with clean fuel.

4. Prepare for colder weather

An aspect of filter clogging trouble is, of course, filters that clog because of the cold. Diesel fuel contains a considerable amount of paraffin, the essential element of solid candle wax! If your fuel gets cold enough, the wax that is normally dissolved in the liquid fuel will solidify and can quickly clog fuel filters. Fuel that does this is said to "gel" and there are many anti-gel fuel additives on the market.

While diesel fuel is required to meet anti-gel standards, these apply to each area of the country, and the standard is set by the average temperature on the date at each location. Thus, it is necessary to prepare yourself for cold snaps when the temperature may be 10-15 degrees colder than average for a few days. It is also essential to realize that if you buy fuel in Miami and drive to Maine, your fuel will not be well adapted to the local climate.

Using an anti-gel additive in winter, especially under those two circumstances, is very helpful. It is also a great idea to ensure you have some sort of fuel heating on your vehicle that either uses engine coolant or power off the electrical system to heat the fuel as it passes through the filters.

Electric heaters that can be used to heat the fuel in the filters prior to starting are available, though judicious use of the right additives makes them less necessary.

Finally, draining water and dirt out of your fuel tanks as specified in your owner's manual will also help with winter operation.

The Electrical System

Batteries are the most vulnerable part of this system, and taking care of them will help keep your lights on and make maintenance easier on the rest of the system.

Similar to fuel filtration, there are 4 main pointers here -

1. Protect your batteries

In late summer or early fall, disconnect all the batteries and load test each one or have this done at an electrical shop. Any battery that has lost a significant percentage of its load-carrying ability should be replaced.

And, ideally, all the batteries should be replaced together. This is good practice because a weak battery transfers load to all the other and tends to over-stress them. Some smart operators simply replace all their batteries every two years.

While they are disconnected, clean every connection so there is only bright metal between parts. When reinstalling all the connections, make sure everything is tight, of course. And, remember that ground cables and their connections are every bit as important as positive cables and connections! Check the resistance of the main cable to the starter, and the cables to the solenoid, and make sure the ground wiring is tight at all connections and that those connections are clean. If your starter sounds lazy‚ turns slowly, check the resistance of the main cable leading to it with an ohmmeter, or have this done at an electrical shop, and replace it if resistance is high.

2. Keep a charger and alternator nearby

Also, it makes sense to keep a good battery charger around. When batteries get low, it's far from ideal to use the truck's alternator to charge them back up after a jump start. The alternator is normally sized only to keep the batteries full and operate the truck's electronics.

If power is available, it's best to use the battery charger for a couple hours before driving off, or use it in place of the jump start!

In cold weather, battery power deteriorates. It can help greatly to have a heater in the battery box, or even to have an insulating blanket around the batteries. They won't charge if very cold, but the power flowing into them will warm them and allow them to charge if they are protected from the cold.

If shutting down the engine and using battery power at night or while you are resting, use an inverter or other system that will cut off power and ensure the batteries won't be discharged too much prior to restarting the truck.

An inverter converts 12-volt DC to 120-volt AC, the ideal way to power appliances like a microwave or refrigerator in the sleeper. Deep cycle batteries may be also helpful when using a lot of battery power in order to avoid idling.

It's important to note that maintaining the batteries and alternator also will preserve the life of the starter. Low voltage increases the amperage‚ the flow of current‚ through the starter even though total power will be less. The heat from the amps is what is destructive. Using the lowest viscosity oil approved for your engine in winter, oil such as 10W-30 or 5W-30, with a low first viscosity number, will also greatly ease the strain on the batteries and starter. Preheating the engine will also help.

3. Maintain emissions after-treatment systems

If you are fortunate enough to be operating a 2007 or even 2010 or newer tractor, you know that these vehicles have sophisticated after-treatment in the form of a DPF (Diesel Particulate Filter) and, after 2009, an SCR or Selective Catalytic Reduction system. While the systems are complex and diagnosis is hardly within the realm of the shade-tree mechanic, there are a few things you can do to forestall problems.

When it comes to diagnosis, the best approach is to develop a good relationship with an honest dealer or independent shop that has well-trained technicians and the right electronic readers to help them diagnose trouble. Regular customers who give the shop a reasonable length of time to fix trouble and approach problems with a positive attitude will usually go out of their way to help you out. Well-organized shops give priority to diagnosing the many minor troubles that occur with today's emission systems within an hour or two so easy, quick repairs can be run through the shop in a day or so. They won't tell you the truck is in line behind big jobs that take several days.

Help maintain your DPF by using good fuel and well-respected fuel additives that will both enhance the cetane rating of your fuel and help to keep injectors clean.

Cetane refers to how quickly the fuel ignites, and the US regulated minimum is only 40. Some engine manufacturers may recommend a higher rating, say 45. Using premium fuel with a higher rating or measuring and adding the right quantity of a high-quality additive each time you fill up will help your fuel ignite earlier after injection, which helps burn off the particulate that the DPF is designed to catch. This will also help cold starting.

Have the DPF cleaned at recommended intervals at a facility that will do a high-quality job, rather than waiting for a diagnostic code. This will also save fuel.

4. Use high-quality engine oil and DEF

It is also essential to use high-quality engine oil that meets the low-ash requirements of modern engines.

Using an engine oil guaranteed to provide considerably less ash than the required minimums is even better, and some have become available in recent years.

Of course, regular oil and filter changes, preferably with the intervals determined by laboratory analysis, by reducing oil consumption, will also help minimize the need to actively regenerate or clean out the DPF. And, avoiding idling and keeping your overheads set properly (more on this in Part 2) will also help.

Using the best quality Diesel Exhaust Fluid or DEF is also helpful when the truck has an SCR system. Poor quality DEF can actually cause sensor failure. Use only reputable brands guaranteed to meet the stringent standards your truck maker has set rather than shopping by price.

Change all fuel and DEF filters in the after-treatment system at factory intervals, too, and inspect the system for any leaks or loose electrical connections periodically.

Experts recommend carefully following all factory recommendations for these systems. And, as soon as you get an engine code from your onboard diagnostic system, take the truck in and get the problem solved.

That covers our fine points of maintenance for fuel filters and electrical systems! Next, jump over to The Fine Points of Engine Maintenance - Part 2, where we'll learn about adjusting your overheads and the cooling systems.

Other relevant articles:

The Fine Points of Engine Maintenance - Part 2

Diesel Emission Controls: Part 1 - History of Standards and Systems

Diesel Emission Control: Part 2 - Truck Maintenance Downsides