Bottom Line
Too hot to handle?
EPA's push-forward of emissions standards left post 10/02 trucks more than a little hot under the hood

By Paul Abelson
senior technical editor

Never has the Law of Unintended Consequences been demonstrated better than it has regarding emissions-controlled engines.

It states that if you make changes, you also wind up with results you didn’t expect – it’s true with products and government regulation.

It’s not always bad. Aspirin was developed to reduce pain. It also thins blood to prevent heart attacks and strokes, saving lives.

But, most often, when we think of this law, we think of adverse consequences.

The law hit trucking in 2003 and 2004, after regulations about air quality went into effect in October 2002. Those regs were originally intended to be effective Jan. 1, 2004.

EPA officials determined that engine manufacturers “cheated” on earlier regulations, using software that improved fuel economy, but allowed higher nitrogen oxides, or NOx. Enginemakers met the EPA-designed tests. They provided the improved economy during steady driving that occurs only in rural environments, where increased NOx have minimal effect.

With their only choices being litigation against the EPA with its deep pockets, or accepting its demands, enginemakers consented to EPA’s demands. Remember, EPA certifies each engine for emissions before it can be sold.

EPA assumed that advancing the 2004 standards by 15 months would, all things being equal, make up for extra NOx emissions. Officials had the enginemakers agree to advance the January 2004 standards to October 2002. That was the now infamous consent decree.

Perhaps the EPA would have been right, had all things been equal. But the Law of Unintended Consequences struck with a vengeance.

Most major customers, already wary about the new exhaust gas recirculation technology designed to meet 2004 standards declined to purchase the new engines except for a few for testing purposes. They chose to pre-buy, to replace older trucks that would have been traded in 2003 and 2004 with pre-10/02 trucks or with good late-model used trucks – an unintended consequence of which was to restore values to the used truck market.

 Another unintended consequence of EPA’s action was to shorten development time by 15 months, leaving enginemakers no choice but to roll out product that was not fully developed. The trucking industry became the final development lab for the new engines.

Hey, it’s getting crowded under here
Another major trend combined to affect the new trucks.

In the desire to improve fuel economy, a situation gaining in importance by the day, truck manufacturers have been improving aerodynamics. That led to designing rounded and narrow noses, sloped hoods, locating air cleaners under the hood instead of out in the air stream, and generally smoothing the exterior. That tightened space under the hood. Suppliers were asked to provide smaller components to operate under greater stress.

The emissions reduction strategies, whether cooled exhaust gas recirculation or compound turbo-charging, brought more heat back under the hood. That heat had to be managed, but in early 10/02 engines, the engine and component suppliers and truck builders did not know how severe the problems were to become.

Underhood heat problems have been discussed at a series of technical sessions at Technology & Maintenance Council meetings, which began in February 2005 and continued through February of this year. The subject was assigned to the Cab and Controls Study Group led by OOIDA member Gail Bristow (formerly Swiger).

The first session, in February 2005, identified major concerns that surfaced as the 2002/2004-compliant engines began to accumulate significant mileage.

The most frequent failures attributed to high underhood heat were fan clutches, hoses, belts, power steering seals, belt tensioners and alternators. Early EGR engines had burn-through problems in the coolers and in the exhaust gas recirculation control valves.

One TMC member used thermocouples to measure heat at various locations on his trucks. He used fully loaded 2005 model year tractors pulling grades with the ambient temperature at 78 degrees.

Under the hood, between the frame rails, sit many heat generators – the engine, its cooling system and fan hub, power steering, the oil cooler, the EGR cooler, turbocharger, oil filters, air filters, fuel filters, the air dryer, air conditioning, hoses, electrical lines, and any added accessories. These all fit within about 80 cubic feet.

As one supplier said, “It gets pretty crowded in there.”

Power steering, made smaller and lighter, now operates at higher pressures than ever before. Design operating temperatures are between 140 degrees and 160 degrees. Failure starts to occur at 235 degrees. In the post 10/02 engines, actual temperatures reach 251 degrees. That’s when seals start to leak.

Engines between 450 hp and 600 hp or more now take less space than what was once needed to house 300 hp engines. Cooling has become a severe challenge.

Cool it? How?
Frames have been widened to support wider, thicker radiators, and radiators have been extended downward – partly to make up for height lost to sloped hoods – for more area.

After flowing through radiators, cooling air must pass around engines with their new EGR coolers, but flow is obstructed by all of the objects under the hood. Obstructed airflow limits cooling. Stop-and-go city driving creates even more severe underhood thermal stress.

Before 10/02, fan drives in on-highway trucks operated about 10 percent of the time. Now, fan clutches must operate for much longer periods for several reasons: Larger cabs are putting greater loads on air conditioners; EGR coolers are increasing the thermal load through the radiator; and accessories are raising underhood temperatures.

As fan clutches operate longer, they use as much as 55 hp to pull air through the radiator. With cooling fan on-times increasing, use per mile is also increased, shortening miles to failure significantly.

Underhood heat softens and stretches polymers and reinforcing material in fan belts. Heat also cooks lubricants in automatic belt tensioners, leading to premature failures of both serpentine belts and the tensioners.

Hoses are designed to stay flexible in extreme cold – minus 40 degrees, where Fahrenheit and Celsius are the same – and retain their strength and shape at high temperatures. For coolant hoses that tolerance has been up to 230 degrees, which is the coolant’s boiling point under pressure, plus a safety margin.

Underhood temperatures as high as 250 degrees accelerate hose deterioration. Even silicone hoses with reinforcing fabric deteriorate. Other hoses subject to thermal stresses include air-to-air cooler hoses, air conditioning hoses, fuel system and fuel return lines, and air brake hoses.

Even alternators have experienced shorter life span in high-temperature environments. Greases cooked out and seals deteriorated.

Coming up next issue
In the next issue, we’ll examine what you can do if you own one of the 2002/2004-compliant trucks. We’ll also look at what makers of engines and components have done to fix these problems for those trucks and for the 2007 models.

Remember, EPA officials created many of these problems by shortening the development time for truck and enginemakers. They did it for noble reasons, but they never considered the unintended consequences of their actions.

Paul Abelson may be reached at