e m i s s i o n s   a u t h o r i t y

New Diesel Report

Post-October '02 engines are mechanically fine, economically not-so-hot.

Tom Berg
Equipment Editor

      Everybody but the EPA wishes they didn't need to be built, but the latest heavy duty diesels are doing pretty well so far, once you get past increased purchase prices and fuel economy penalties. A typical heavy duty tractor with a post-October '02 diesel costs $3,000 to $5,000 more than before, and fuel economy has generally dropped by 1% to 8%.
      Reliability of new diesels ranges from very good to OK and improving, said fleet managers who are running them.
      "The jury is still out on longevity" of all post-October '02 engines, said Herman Miller, chairman of an industry task force that is surveying members on the new engines. Miller, fleet equipment manager of SVS Trucking in DePere, Wis., said none of the new engines have been operating long enough to know how they'll be doing as they get well into their anticipated million-mile life spans. At this point, no in-service engine has gone beyond 200,000 or 250,000 miles, he figures.

2 Cents A Mile

      Higher purchase prices and fuel economy degradation may add 2 cents per mile to the lifetime cost of operating an October '02 engine, according to calculations done by Joe Stianche, fleet manager at Sanderson Farms, a poultry processor headquartered in Laurel, Miss. That assumes an extra $3,000 up front, 5% worse fuel economy and diesel fuel at $1.30 per gallon.
      "It's unavoidable, it's real and it won't go away," Stianche said in mid-December. "It's a cost of doing business that has to be recovered" through higher product prices and freight rates.
      He runs a widely varied fleet with Cat C13 ACERT engines on order. The fleet includes local and long-haul International tractors with 11 Cat C-12 Clean Power diesels — very reliable, but they cost more to buy and they burn more fuel.
      "It's hard to determine what an engine costs in a certain chassis because there are fewer choices," Stianche says in reference to truck makers' paring back engine options. "We have to burn more fuel to get cleaner air — that's an oxymoron to me," he adds, echoing a long-standing industry argument that burning less fuel causes less pollution overall.
      Fuel economy of 25 Mack ASET (application-specific emissions technology) diesels in highway tractors is down by 0.2 mile per gallon or 3%, reports Darry Stuart of Wrenthum, Mass., an industry veteran who helps manage fleets under contract. Otherwise, he said, the Macks are doing a good job. "We haven't heard anything negative. Oh, we had a few turbocharger screws come loose, but the manufacturer fixed those under warranty."
      Stuart said the aftertreatment converters used with Cat engines are proving extremely reliable, according to what he's heard from managers running them. Cat uses converters on Clean Power and ACERT engines, and before that used them on midrange 3126E diesels.

Elusive Problem

      U.S. Xpress Enterprises of Tunnel Hill, Ga., has had some frustrating reliability problems with some of its new engines, according to Marty Fletcher, the progressive truckload carrier's director of technology & training. It has 650 Freightliner, Volvo and Peterbilt tractors with Cat C15 ACERT, Cummins ISX, Detroit Series 60 and Volvo VE D12 diesels. Fletcher is a pioneer user of Eaton AutoShift automated mechanical transmissions, which are electronically connected to the engines and thus affected, too.
      Electronic controls have sensed problems in EGR systems and cut back on engine horsepower, crippling trucks and putting them on shoulders. Drivers shut off the engines, wait a bit, then restart, and the engines are again fine. In some cases the engine controls disrupt operation of the AutoShift transmissions. But technicians say later they can't find what caused the problems.
      Fletcher and Stianche were on a panel of five managers during the American Trucking Assns.' annual meeting. Another panelist was Dwayne Haug, vice president of maintenance at Werner Enterprises in Omaha, Neb. Fuel economy of Werner's Cat ACERT and Detroit EGR'd engines is down by 3% to 5% and sometimes as much as 7% to 8%. "Unfortunately, they haven't gotten any better" with more miles, he said. "The numbers stay the same through the break-in period, which is different" than with pre-October '02 engines.
      Haug wonders if fuel economy will get even worse with engines built since Jan. 1, when auxiliary emissions control devices, or AECDs, are tightened. AECDs, a function of engines' electronic controls, ease up to protect engines during cold starts, high heat and high altitudes. In some cases these must be modified under EPA rules for '04.
      Jeff Philpot of Kirk NationaLease in Sidney, Ohio, conducted tests of pre-October '02 Cummins ISX diesels in Volvo tractors and post-October ISXs in Peterbilts. His tests showed the older trucks got 7.3 mpg and the newer ones got only 6.15 mpg — a difference of almost 16%.
      But in a more valid Volvo-to-Volvo test, the "pre" engines got 6.79 mpg while the "post" engines got 6.5 — a spread of 4%. This was at Ohio's 55-mph speed limit, so running faster may alter the outcome. And, Philpot asked, will the altering of AECDs result in another 3% loss?

Not So Bad

      Dennis Soch, fleet operations manager at Kellogg Snack Foods in Elmhurst, Ill., said the economy loss by two post-October Volvo VE D12 engines is under 1% — 0.06 and 0.09%, exactly — compared to a pair of pre-October VE D12s. He's had no EGR-related problems and like other managers, has been able to keep the same oil change intervals. "Overall, we're surprised they're doing as good as they are," Soch said. But he doesn't like increased costs of purchasing and fuel.
      Herman Miller, the TMC task force chairman, said he wonders if comparisons made by some managers are accurate. For example, they'll compare new trucks with older ones in the fleet and disregard the negative effect of new, deep-tread tires versus half-worn tires on the older trucks. Worn tires roll easier, helping their trucks' economy and making the pre-October engines look better than they are.
      Also, "bigger fleets are trying to do fuel economy [measuring] by ECM"— taking data from their engines' electronic control modules. "That's a very poor way, because you're relying on the manufacturers getting it exactly right," Miller says. ECM fuel-flow measurements are based on volume, which changes with ambient temperature, and that has to throw off miles-per-gallon numbers.
      "A 7,500-gallon load of fuel can change as much as 200 gallons, depending on whether you get it on a day when it's 80 degrees outside or a day when it's 20 degrees," Miller says. Temperature "makes a huge amount of difference," and the same is true of fuel as it flows into the engine's lines at varying temps. The only scientifically accurate way to measure fuel is to weigh it — not count it by gallon — at the industry testing standard of 60 degrees, or at least to perform comparison tests on the same day. These are part of the fuel economy testing procedures established by TMC and the Society of Automotive Engineers.
      "So I don't think fuel economy is as bad as we thought," Miller says of the new engines.

Diesel Report continued...