Dollars & Sense

Kevin Rutherford

Dollars and Sense

Kevin Rutherford | April 01, 2010

kevinEarly PM can pay big dividends

Catching problems with oft-overlooked maintenance items can pay big dividends. Timely replacement of these problems can make great contributions to robust preventive maintenance programs, reducing thousands of dollars a year in operational costs by helping you avoid breakdowns and provide better service to your customers.

CHARGE AIR COOLER. The CAC is the most overlooked item on a Class 8 tractor. It sits in front of the radiator and looks like a radiator. In essence, that’s what it is. It is designed to cool superheated air from the turbo before it gets into the intake manifold for more efficient combustion.

Seeing a water leak from a radiator is easy, but your CAC needs to be pressure-tested to find leaks. You can make or purchase a test kit, or have it done at any engine shop. Each engine manufacturer sets a limit on how much CAC pressure loss is acceptable, usually 5 to 7 pounds in 15 seconds.

But given the immediate drop in fuel mileage a leaky CAC causes, I’ve found it makes sense to replace a unit that leaks just 2 pounds in 15 seconds. At that level, at 2,500 weekly miles at 6 mpg and $2.75 per gallon, you’d be losing $88 a week. You’ll spend $1,000 to $2,000 to get the CAC replaced with a good aftermarket cooler. Your breakeven comes in less than six months, and your return on investment will be substantial.

This doesn’t take into account other problems associated with a failing CAC, which can include engine power loss, exhaust manifold failure, premature piston ring and valve failure, elevated engine coolant temperatures and turbocharger failures. I recommend testing the CAC every three months or anytime you see a drop of 0.3 to 0.4 mpg that can’t be explained any other way.

CRANKSHAFT DAMPER. Most engine shops will tell you this doesn’t need to be replaced. They don’t even replace it on an in-frame. This is a mistake.

The crankshaft damper, designed to reduce torsional twisting from the force of the connecting rods being driven down by the combustion, wears out. Consequently, engine force and vibration are transmitted throughout the entire frame and driveline. This leads to many problems, not the least of which is driver fatigue.

Maintenance problems run the range of broken alternator brackets, broken air-conditioning brackets, clutch and driveline problems and even loose or faulty electrical connections. There is no way to inspect a crankshaft damper. I recommend replacing it at 500,000 miles. It will cost $700 to $1,000. Volvo engines are an exception, where the crankshaft damper is internal and cannot be replaced easily.

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A technician works on a clutch at Western Truck Parts in Henderson, Colo. Clutch failure is among the problems that can result from a faulty crankshaft damper.

It’s hard to calculate a true return on investment for crankshaft damper replacement, but every operator I know who has replaced the damper is pleased with the results. I guarantee it will help you avoid maintenance costs.

RUBBER FLEXIBLE FUEL LINES. These can deteriorate internally with no visible wear or damage. Internal deterioration can cause lines to swell and restrict fuel flow, triggering fuel-mileage declines and power loss. Trucks with fuel mileage issues can benefit from line replacement ($300-$400) to the tune of 0.3 to 0.4 mpg. If your truck has more than 700,000 miles and an unexplained loss in mpg, I would recommend it.

FACTORY MUFFLERS. These cause exhaust restrictions from day one. The longer they’re used, the more soot build-up you see in the muffler itself, and the more exhaust restriction is created. Restriction robs your engine of performance, power and mpg. You can install a high-performance flow-through muffler on most trucks for under $200, and your return on investment is nearly immediate. You’ll also notice much better throttle response.

  • BRIAN SCHARFF

    I NEED INFO HOW TO SPEC A TRUCK.Run fiat land in ohio .tanker lpg . like petes cummins What gears? run heavy 50% of time . need to littin up and get the best fuel mileage i can.Anbody a can talk to THANKS Brian Scharff