Time for an overhaul
Wittwer says you might see gradually increasing blow-by. Don’t be alarmed, but if it increases a lot over time, have it inspected. “I’ve had lot of drivers say they’ve had excessive blow-by. All of a sudden they’re pulling a hill at night and guys behind them say it looks like their truck’s on fire. That’s when they’ve got to get something taken care of.”
How far to go
When internal damage is found early, the engine can be taken apart to see if a rebuild or replacement is in order, Mack Engines’ Long says. “If a customer decides to rebuild, he may only want to replace the rod and main bearings or perform a full rebuild,” he says.
Once the inspection has taken place, parts replacement is often wise. Rod, main and cam bearings, pistons, piston rings and liners, oil pump, thermostat and all seals and gaskets should be replaced, says Rick Cape, Mack’s remanufactured technical product manager. The water pump, injector cups and even the injectors might have to be replaced, too. At the same time, the turbocharger and items like the camshaft, rocker arms and shaft and gears should be inspected for wear, he says.
“If a rod or main bearing has failed, the crankshaft may need to be turned or polished to remove scratches made by the bearing as it failed,” Cape says. “Cylinder head work such as resurfacing, valve replacement, valve grinding and valve guide replacement should be done using new or factory-remanufactured cylinder heads.”
An experienced technician can determine if a part is worn beyond its service life.
Simple clues of engine failure
While lab and shop tests are crucial to monitoring engine wear, don’t forget more basic ways to detect engine problems. Even just sight or touch can give you clues that something might be wrong.
WATER IN THE OIL. This will manifest itself as “foam or gunk on the fill cap or neck or on the dipstick,” Richard Hassebrock of Castrol says. “Sometimes water droplets will form on the dipstick and rust will develop.”
OIL OVERHEATING. Oil that’s overheating smells like burning oil.
FUEL DILUTION. You can also smell a high level of fuel dilution. With injection system failure, fuel that isn’t fully atomized works its way past the piston rings and into the crankcase. Oil viscosity will decrease and oil will smell like fuel, Hassebrock says. “Put a drop of oil on the back of a business card and watch it spread,” he says. Rapid spreading indicates fuel.
ENGINE NOISE. Listen closely. If your engine’s pinging or running roughly, take it to the shop.
EXHAUST SMOKE. Trouble’s at hand if you see heavy smoke in the exhaust, Hassebrock says, or blue smoke with pre-2007 engines.
LOOSE SEALS. Look daily for loose seals around the intake piping that could lead to contamination of the intake track, recommends Danny Long of Mack Engine. Dirt or dust could cause premature wear of piston rings and turbochargers, thereby contaminating the oil.
ANTIFREEZE CONTAMINATION. Low cylinder compression can be a sign of worn liners, piston rings or valves, which can be caused by antifreeze contamination of the oil, Long says. Run a compression test on each cylinder to know for sure.
OIL FILTER TEST. A technician can use a special tool to cut open the filter and look for signs of metal in its pleats. Certain engine problems can produce large metal particles that aren’t found in oil analysis because they become lodged in the filter, Hassebrock says. “If you see large particles there, notify the lab to do additional analysis besides the spectrographic analysis.”
OIL PRESSURE GAUGE. While the gauge may not be perfectly calibrated, if you see a noticeable change in its reading, take action, Gambill says. “It could mean something’s wrong with the gauge, but it could also mean you’re not getting proper oil flow.”