Bottom Line
Maintenance Q&A
Sniffing out some smelly problems

By Paul Abelson, senior technical editor

Q.  In November 2010, I bought a used Freightliner Columbia from a well-known fleet. It had about 460,000 miles on it, not too bad for a five-year-old truck. The truck is running fine, but this summer I started noticing some weird smells, almost like rotting meat. I opened the windows and the smell went away. Sometimes it would come back after the truck had been sitting.

I changed the cabin air filter, but that didn’t seem to make much difference. It still came back. It was even stronger on hot days. How can I get rid of it? I love how the truck runs, but the smell drives me crazy some days.

A. There are certain unanticipated risks when buying a used fleet truck, and smells are among them. Some of the largest fleets have special cab cleaning teams to work on trucks when they’re turned in by drivers leaving the company or, unfortunately, when drivers have passed away in their trucks. According to information presented at a recent TMC meeting, that happens more often at the larger fleets than we might expect, but, thankfully, it’s relatively rare.

Among the things the special teams deal with regularly are debris removal, including stale and rotted foods, pet hair and pet waste, mold in hard surfaces like dash panels and sleeper bulkheads and in soft surfaces such as seat cushions and curtains. Blood is, of course, a biohazard along with other bodily fluids and wastes.

When professionals deal with a problem truck, they may have to dismantle the cab bit by bit until problems are found. This can involve removing seats, carpets or mats, wall linings, mattresses and virtually any surface that can be detached and removed.

Surface cleaning is best done using solvents and disinfectants followed by steam cleaning. Urine stains should be treated with uric acid. Whenever using strong chemicals, wear protective clothing. At the least, wear latex or nitrile rubber gloves and eye protection. Clean thoroughly between mating surfaces and in grooves. In sleeper cabs, be alert for bedbug infestations.

If this has discouraged you from making this a do-it-yourself project, that might be a good thing. Professional disaster restoration companies have the tools, supplies, knowledge and equipment to do the kind of cleaning you might need. They also can clean your truck without violating any EPA or OSHA regulations.

Q. I heard that they are increasing the amount of biodiesel allowed in truck fuel. Are there any problems increasing from B5 to B10? (The numbers refer to 5 percent and 10 percent biodiesel, respectively.)

A. Engine manufacturers have been following the effects of biodiesel on their engines, and then certifying the engines accordingly. Early biodiesel blends were limited to just 2 percent (B2). The fuel had no adverse effect on seals, gaskets and other fuel systems parts. In fact, 2 percent biodiesel restored all the lubrication lost with the removal of sulfur to create ultra-low-sulfur diesel (ULSD). Sulfur, with its inherent slipperiness, went from 500 parts per million to just 15 ppm in ULSD.

Biodiesel is slightly acidic, and it tends not to cook out like the acids in regular petroleum diesel. Still, engine manufacturers have increased allowable biodiesel content from B2 to B5, then B10. And today many authorize the use of B20 in EPA 2010 engines.

One major concern involves leaking injectors. The common maintenance issue allows fuel to leak into the oil pan. Biodiesel mixed with engine oil promotes oxidation of the oil, deposit formation, and corrosion of lubricated parts, especially bearings.

The process of developing the next oil category, PC11, has already started at the American Petroleum Institute. A great many decisions and compromises are yet to be made between now and January 2016, the target date for the proposed category’s introduction, but the oil is expected to be more compatible with higher biodiesel concentrations. And as a fuel-saving measure, lower viscosity oils like 5W-40 and 5W-30 are expected to be approved for general use in big-bore diesels. LL