Detroit Diesel leaves two-cycle engines behind

Few engine companies have had as many breaks with the past as Detroit Diesel. First it was part of General Motors, then Roger Penske took it over, and now it’s under the ownership of DaimlerChrysler, which has added the MTU brand to all the engines. 

The biggest change took place in the late 1990s when the tried-and-true but polluting two-cycle diesels were dropped and replaced with a completely new line of four-cycle engines. 

The old warhorses like Detroit Diesel’s 6-71 and 12-71 — favored by many commercial operators because they were reliable and relatively easy to repair — are gone. But some of the new Detroit Diesel/MTU engines are starting to make a mark. For example, the 4000 series is already proving to be more durable than originally expected, as measured by overhaul periods. 

For the continuous-duty rating at 1,800 rpm, an overhaul was originally pegged at 24,000 hours. 

“We can get up to 30,000 hours easily,” said John Todd, with Pacific Detroit Diesel-Allison’s commercial engine sales in Kent, Wash.

Engines at the 1,600-rpm rating were originally scheduled for a 30,000-hour overhaul, but Todd said these engines can probably go longer.

One advantage of launching a completely new line of engines is the ability to start with a blank sheet. Fuel systems are important for the longevity of any engine, and Todd said the choice of a common-rail fuel system for the 4000 series makes it the first high-speed diesel to use this type of fueling. 

An advantage of the common-rail fuel system is that it has a cooler combustion, which reduces nitrous oxide emissions. “The combustion is less violent, thus there is less noise,” Todd added.

When the engines do have to be repaired, Todd said there are a couple of factors that make the work less intensive than with engines from other manufacturers. “They are designed in a modular fashion so they can be taken apart and put back together quickly,” he said. 

And since all the engine components are water cooled, water-cooled shields aren’t necessary, Todd said. 

With this engine cooling, 60 percent less heat is radiated into the engine room, which cuts the costs and space needed for ventilation equipment. 

Todd said the 4000 series engines are being used on the West Coast in boats for ship-assist and dredging work, ferries and excursion boats.                                             — M. Crowley 

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