Dodging Downtime Disasters

Effective management means identifying the things that cripple trucks, and dealing with them before they become emergencies.

July 2007, - Feature

by Tom Berg & Steve Sturgess

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Obviously, this can be done through experience, aided by good recordkeeping, and by getting information from other sources, including colleagues, dealers and suppliers. It's also useful to consider what causes equipment breakdowns in the industry as a whole. Here we offer information on the leading causes of breakdowns, gleaned from the extensive database of FleetNet America, the national breakdown and recovery service, and offer our top tips for enhancing reliability and uptime based on what we've seen over the years.


Among the most frequent road service calls are those for blown tires. Tires not only head the list, they dwarf all the other breakdown causes, accounting for nearly half of the breakdown dollars. Are they preventable? For the most part, they are, say tire manufacturers and tire experts. Usually they're caused by underinflation, which leads to overheating and then to the blowout. Sometimes nails and other road hazards have caused punctures and air leaks, but more often tires fail because no one's bothered to check them.

Experts say every tire on every vehicle should be "stuck" with a gauge once a week to measure air pressure, and those that are low should be replenished. Those that are especially low – some say 10 percent or more below the desired air pressure is a danger sign – should be pulled and the probable air leak found and fixed. It takes an active tire management program to accomplish all that, and in the real world, failures occur even the best-managed program.

The best person to watch the tires is the rig's driver. Conscientious drivers do it because it's part of the profession. More drivers will bother with the tires if they're given the tools and necessary encouragement. One small fleet owner we met equipped each tractor with a 50-foot air hose and a quick-connect coupling on an air tank (gladhand connectors also work, but they're much slower at pumping up tires), and, of course, an accurate gauge. A driver who found tires that were low didn't need to find a charged hose somewhere at a truckstop; he could air up the tires right where he was parked. The owner paid his drivers a few extra bucks a week to use this equipment, and claimed that they actually did.

Of course, mechanical and electronic tire pressure monitors can keep tabs on inflation levels, and automatic inflation systems can keep them aired up. These can be especially valuable on trailers, which spend most of their time away from home and sitting on strangers' properties. That's why owners of intermodal chassis are some of the biggest customers for inflation systems.

Many owner-operators don't trust retreads and insist on running only new tires. That mistrust is mostly misplaced, because quality retreads can last as long as an original tire and be just as reliable. Just ask Harvey Brodsky of the Tire Retread Information Bureau. He'll tell you (and back it up with proof) most of those road alligators are from new tires that have been run with insufficient air pressure.

But one owner-operator we rode with had another reason for buying new: They look good, and that makes an impression on equipment inspectors. He brought this up as we were passing through a weigh station where a class of novice state motor-carrier inspectors was being trained. Dressed in new blue coveralls, they were gathered with an instructor, next to the lane used by trucks as they came off the scale.

"Watch what they all look at," the o-o said as we slowly drove by them. Sure enough, every eye was on our tires. "They figure that if the tires look good, the rest of the truck is, too, and they'll let you go. If the tires look ratty, they're more likely to pull you in and inspect everything." With decent-looking tires (matched by the rest of the rig's sharp appearance and overall condition, not incidentally) we motored on without a delay, our uptime intact.


Monitor electrical components and other accessories. Battery and alternator failures cause many delays and some breakdowns. A no-start from rundown batteries will eat up an hour, even if a rig's at a truckstop where help is close, and much more if a road service truck has to be summoned. And what will the charge for a jump start be – 50 bucks? A couple of hundred? What'll it cost to replace one or more batteries on the road – twice or more what you could've bought it for at home?

Ditto for the alternator, which of course is the heart of the vehicle's charging system, and the cable between it and the batteries. These must all be maintained – connections should all be "tight and bright," as they say in the shops – but the components should also be regularly tested for output, resistance and other factors. Even so, they'll eventually fail, so the trick is to estimate when that will be and replace the part before the failure occurs.

In recent years, jump starts have risen to be the number 3 cause of breakdowns, as more drivers find themselves spending more time in the trucks drawing down batteries with ever-increasing hotel loads.

Spec'ing a low-voltage disconnect switch is one answer. The switch reads the battery voltage and disconnects the loads as the battery draws down to a voltage that will fail to kick over the engine. Another solution would be to spec a restart system such as the Temp-A-Start that cranks and runs the engine for a few minutes to recharge the vehicle batteries.

A third option: Fit an auxiliary power unit, either diesel or electric powered. They run climate systems and charge the vehicle batteries, or use a separate battery pack entirely for HVAC.

Replacing alternators has dropped to fourth place as a leading cause of breakdowns, indicating that alternators are more robust, despite the higher underhood temps since the introduction of exhaust-gas recirculation in late 2002.

The improvement may be traceable to the upgrades the alternator manufacturers have made in response to the increasing demands on the alternators from higher hotel and electrical equipment loads, as well as the higher-temperature environment. But alternator diagnostics and prognostics could go a long way to pushing the problem even further down the list.


Recordkeeping by fleet managers can result in prognoses for a variety of accessories, helping you to preemptively replace parts. For instance, this alternator has been failing at about 225,000 miles, so let's replace it before it gets to that. Of course, this doesn't work if you can't get the same part in a new truck order, and the anticipated life of an unfamiliar accessory that you have to accept is unknown. But data might be obtained from people who already run trucks with this thing on them – a good reason to join and get active in a maintenance group whose members concern themselves with such things. The part's manufacturer might also be a good source. If his predictions seem unrealistic, an outside maintenance consultant might provide some valuable advice.

If you buy used trucks, test major components and replace others before striking a deal or taking delivery. At the very least, you should have the engine checked for blow-by, which indicates the health of pistons, rings and valves, and insist on a federal DOT safety inspection, which looks at brakes, tires, belts and other critical items. Some used-truck dealers will gladly do this if you ask for it, though of course it will affect the price. And they'll offer warranties that reduce the risk of ownership and enhance reliability, because the warranty companies will hedge their bets by conducting their own inspections.

Used trucks almost beg for pre-emptive parts replacement. Of what? We could take cues from one major truck manufacturer which, when faced with a glut of trade-ins in the late '90s, set up a refurbishing operation. Used tractors, most with fewer than 500,000 miles on their odometers, were stripped of worn or suspect components as they came down a reverse assembly line. Among the items replaced on all trucks were alternators, batteries, air conditioning compressors and tires. Some of the replacements were remanufactured and many tires were recaps, but all were quality, name-brand products.

As part of this process, all fluids in the engines and gearboxes were changed, and remanufactured or new components occasionally installed. Many metal items were polished, interiors cleaned and re-upholstered where needed, and exterior paint polished or resprayed.

Buyers, which included dealers as well as truck operators, could choose many options, from interior trim levels to dual chromed exhaust stacks. The overall idea, though, was to sell trucks that looked better than most used vehicles and were inherently reliable – almost as good as new – at far less than the price of new. Many dealers can duplicate much of this process.

But the pre-emptive strike won't solve all your roadside woes. FleetNet President Oren Summer says tow trucks have seen an increase in business as tractors become more complex and technicians less able to diagnose problems at the roadside.

These could be any of a wide range of problems, as we ourselves experienced when a turbocharger controller failed during a new-truck road test last year. The diagnostic equipment didn't throw a fault code on the dashboard and we had no option but to tow the truck to a dealership. Even then, it took a day and experts from the engine OEM to find the problem.

These types of problems are not ones you're likely to solve through routine maintenance.


Consistently in fifth place on FleetNet's breakdown list are brakes, and even more often an air line problem. It's happened to us twice. Once in Colorado at a scale: "You'll be my guest for the next hour," said the inspecting officer, who found a front brake hose routed too close to the suspension on a brand-new truck.

The other time was on a 35-year-old truck. "Don't you think those (rubber) air lines look a little old?" asked Editor Deb Whistler as we coupled up the trailer to the 1966 Autocar. Sure enough, about 30 miles into the trip the service line let go. We did manage to limp in to a truckstop and get a mobile truck service to cobble up some new lines. Expensive? Yes. Preventable? You bet.

Another leading cause of breakdowns is brake chambers – specifically rectifying or replacing them. According to Summer, the most likely cause is brakes being out of adjustment, which requires a brake-certified technician to adjust the chamber travel, or to replace the whole chamber because of a diaphragm failure.

Brakes out of adjustment should be noted by a driver on his daily walk-around and the problem fixed before the truck goes out. And brakes should certainly get attention if a truck and trailer goes through a safety lane when it returns to a terminal. A leaking diaphragm may be detected early by the sound of escaping air. Leaking air overnight and long build-up in the morning should be written up on the driver's daily report and rectified in the shop.

And "brakes – major" makes an alarming appearance on Summer's most recent top 20 breakdown causes list. There's no supporting detail, but it comes at a time when brake electronic complexity is increasing, with stability control systems placed on top of anti-lock braking.


Fuel filters have also climbed up higher on the breakdown list. Mostly the issue is related to clogging in frigid weather, but there have been a rash of filter problems related to biodiesel.

There should be no issues with running up to a B5 fuel (5 percent biodiesel, 95 percent petroleum-based diesel), provided that when you switch, you put a case of filters on the truck. There will be filter-clogging issues. Biodiesel serves as a solvent, clearing out old fuel residues in the truck's system, which then clog up the filters.

After using up a number of filters, the system should be clean and the truck will run perfectly. That's assuming the biodiesel in the blend meets quality standards, so pay attention to who you're buying from and practice good fuel storage maintenance procedures.

Paying attention to fuel quality in general, biodiesel or not, will help promote uptime. As fuel systems get more complex and go to ever-tighter tolerances, contaminants in the fuel can wreak havoc on injectors.


Aggressive anti-icing chemicals used by highway departments in recent years have lowered the expected service life of trailers by several years. Mechanics have discovered metal corrosion in key places, like inside the upper coupler assembly, that can't easily be repaired. Managers have complained of damage to vehicle running gear, including brake shoes and drums, that directly impact safety and sometimes longevity.

Even if you're not based in snow country, you need to keep equipment clean and regularly inspect your trucks for corrosion troubles if rigs run in winter-weather states. Make corrosion resistance one of your criteria when spec'ing equipment, and look into protective coatings.


Currently, electrical problems with wiring, bulbs and so on are frequent causes of breakdowns or road calls on FleetNet's list. Another top cause is turbocharger failures.

Clutches have also been this high on the list, but things seem to be improving in that department. Improving clutch reliability may be a reflection of the escalating use of automated transmissions.

Air leaks and valve failures are also in the top 10 causes of failures. As you run down the list of frequent failures, you'll find radiator hoses, which may be a consequence of higher underhood and coolant temperatures. Gladhands also make an appearance on the latest list. They never made it into the top 20 breakdown causes before, which makes a case for buying for branded items with quality seals.

Light assemblies are also proving to be more troublesome, curiously, as there appear to be more and more LEDs on both tractors and trailers. Of course, at the same time, headlights have been getting more complex.

Water pumps have had their day in the failure-causing limelight, but didn't make it onto the most recent top 20 breakdown list. This is perhaps a consequence of a shift to extended-life organic-acid coolants.

Many of these can be addressed through regular PMs, which should include things like inspections of hoses. PMs should address traditional routine items, and perhaps add testing and/or replacement of parts that can cause breakdowns if otherwise left to fail on their own.

If trucks regularly visit fuel islands or shops, everyone who touches them should be trained to look for problems and signs of them. There should be effective ways to report any equipment issues so they can be dealt with immediately – before there's a failure.


Running the newest equipment you can afford is a good way to avoid downtime disasters. Fleets that contract with owner-operators often stipulate an age limit for tractors – five years is typical – because managers know older trucks break down more often than newer ones. This seems like common sense, but some contractors insist that they take good care of their older tractors, so they're as good as new. Sometimes they are and sometimes they're not.

In general, keeping the fleet fresh boosts reliability and eliminates the need to invest in maintenance infrastructure. Many fleet executives stay out of the maintenance business entirely by buying new tractors and trading them before they're out of warranty. That way, dealers do all the scheduled and unscheduled work, and there should be few, if any, out-of-pocket costs.

It's almost like full-service leasing, which is attractive to many truck operators – usually private fleets – who don't want to spend a lot of time keeping trucks running.

By the late '90s, life cycles at some for-hire fleets got as low as two to three years. But the '00-01 recession caused some to hang on to their equipment longer, while higher prices for complex, cleaner-burning diesels starting in late '02 led to more rethinking of the trade-in-often strategy.

Fleets with shops and mechanics can keep power units running for a long time, and owner-operators who are handy with a wrench have been doing this for years (though now they also have to be good with a laptop computer and diagnostic software – or know somebody who is).

Long-lasting major components make extended equipment lives feasible. But even if the basic "iron" in engines and transmissions will last a million miles, things such as turbochargers, injectors, pumps, electronic sensors, electric connectors and other items must be repaired or changed out at certain intervals or on an as-needed basis. And cab parts wear out – door latches and hinges, switches and dome lights that dealers might or might not stock as a particular model ages in the lineup or goes out of production.

Tax write-offs are another argument for trading in and buying new or late-model vehicles.

But that equipment should be as reliable as possible. Pick the brains of colleagues, dealer sales and service people and technicians in independent shops to find out which makes and models of trucks and trailers and which components are holding up best.

The latest stuff might indeed be the greatest – or the source of new grief. That's why small operations tend to wait for big, progressive fleets to discover problems with new components. They also wait for manufacturers to correct any problems before buying.

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