A Better Blend

| April 07, 2005

Shenk says that in Macks’ case, the company’s service bulletins also list the specifications. You might be able to compare those with detailed manufacturers spec’s, as Clevenger also suggested. Such spec’s would include, for example, not only the efficiency of the filter in terms of what it removes, but its capacity to hold enough total material. In any event, Shenk agrees with Clevenger that, “The key is to stick with the major, reputable heavy duty filter manufacturers.” That’s good protection if you can’t get a written guarantee or review printed spec’s.

Caterpillar’s Shumaker says, “Assuming the customer has not entered into a Customer Support Agreement with his dealer, the warranty is not dependent upon the use of OEM parts.” She goes on to say that, although Caterpillar recommends the use of Caterpillar branded filters and does not formally list any others, you should talk to your dealer to find out about filters that will maintain your warranty and protect your engine. Getting approval for the brand you are buying is always helpful.

There’s one additional concern if you are running extended change intervals. The media must be designed to stand up as long as the filter is on the engine. This sometimes means a change in the type of media. Clevenger says, “Paper may turn to mush. Resin binders that hold the paper in position may fail.” Use a filter specifically designed for the interval you are running no matter how long it is.


The EGR Principle

In the comic strip L’il Abner, Gen. Bullmoose invented a car that would run on smog. In real life, most truck engine makers use exhaust gas recirculation, which is the opposite of Bullmoose’s idea. EGR is a way to dampen the fire in a diesel cylinder. The exhaust that’s put back in absorbs heat so less nitrogen and oxygen will combine and form polluting nitrogen-oxides (NOx). EGR cuts NOx to half the prior allowable level.

The turbochargers on the new Cummins, Detroit Diesel, and Mack engines have variable geometry-a way to boost back pressure in the exhaust manifold, forcing exhaust into the intake manifold even though it’s already pressurized by the turbo’s compressor. The exhaust takes a different path from the engine’s intake air, passing through a jacket water exhaust gas cooler rather than the charge air cooler. The exhaust cooler uses only jacket water at 180 degrees and up. This is done to keep water and acids that are in the exhaust from cooling and turning into a liquid. This will minimize their impact on the engine.

Volvo, too, uses an EGR system with jacket-water-cooling. But, the Volvo V-Pulse system develops the pressure necessary to force exhaust to recirculate using the pressure pulses in the exhaust manifold.

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