Maintenance Q&A
Dealing with slime and beat-up bushings

By Paul Abelson, senior technical editor

Q. How do I remove the algae that have appeared in my fuel tank? 

A. Algae, fungus and other organisms in general are airborne, so you’ll never be able to keep them completely out of your tanks. They enter when fueling and through the vent system. Once your tanks are clean, organics are easy to control. Left uncontrolled, that slimy organic growth can plug fuel filters and, if they get that far, foul the fuel pump and plug injectors.

Start by running your tanks as low as possible. If you can, plan to return to your shop nearly empty. Drain what’s left into a clean container if you plan to salvage any of it. At prices near $4, every gallon saved is precious. Responsibly dispose of what you don’t salvage. Water is heavier than diesel, and the slime generally grows in between fuel (its source of food) and water (its source of oxygen). Water will drain first. As it changes from water to fuel, it will start to get slimy. When or if the fuel starts to appear clean, you can save the remainder in a clean, closable fuel container.

Inspect the insides of the tanks. If there is a heavy slime coating, you’ll need to kill the organics with a heavy dose of a fuel biocide. Bioban GA50 and Kathon FP are effective. Bioban works in as little as one to four hours. Kathon and others may take 24 to 48 hours.

Caution: There are strict EPA rules on using biocides. Read all the directions on the labels, including instructions on disposal. Wear protective equipment whenever working with biocides.

You can usually dispose of the fuel dosed with biocide by running the engine in normal service. Be prepared to change fuel filters several times (depending on how much slime there is) when you burn off the biocide-fuel mixture.

If the tanks are not too contaminated, you can add reduced quantities of Bioban or Kathon, or use biocides designed for use in the fuel. Biobor, Power Service’s BioKleen, Penray’s Fuel Prep, BioGuard and Bio-Blast are often found in truck stops – or boaters’ or marine supply stores, or even online. West Marine is one of the largest.

It’s a good idea to treat your tanks with a biocide twice a year. Many do it when winterizing and summerizing their trucks. Fuel additives such as FPPF, Howes, Lucas or Power Service should be used on a regular basis. In addition to delaying gelling in winter and keeping the fuel system clean and lubricated, they manage water, which slows organic growth. 

Q. I have a 2006 Peterbilt 379 pulling a 2002 Dorsey dry van with air ride. I noticed uneven wear on the trailer tires. They seem to be cupping and it repeats around the tread. I noticed a vibration from the trailer.

My tire dealer checked the tire mounting, which seemed OK. Then he checked the trailer tandem alignment. To even out the tire wear, he rotated them so what was rolling clockwise on the right side was now rolling counterclockwise on the left. He also checked the shocks two ways.

He visually inspected them for leaks, and took the truck for a test ride after which he used an infrared gun thermometer to check the temperatures. They were all warm but different, within 10 or 15 degrees of each other. He said that was normal and didn’t need changing.

That was about 12,000 miles ago. The vibration seemed to disappear and the wear seemed to even out, but now the symptoms are back. Short of buying eight new tires, is there anything I can do?

A. Did you recheck your shocks? If they’re wearing out, a great deal of deterioration can happen in 12,000 miles. It’s also possible your suspension or shock absorber bushings could be shot. Most are made from rubber, which can be attacked by road spray and even oxygen. Bushings get beat up by design. Their function is not to absorb impact, although they often have to. They allow for the temporary misalignment of suspension components and then return them to proper alignment when the load is removed.

Your bushings at anchor points for the suspension have seen quite a bit of stress in the 12 years you’ve had the trailer. You seem to have paid attention to your shocks, but if you’re like most, not so much to bushings.

TMC’s Recommended Practice RP643, Air Ride Suspension Maintenance Guidelines, suggests that while bushings normally do not require preventive maintenance (unless they are metal and have grease fittings), they should be inspected annually. They suggest checking by applying force with a jack or a pry bar. Mark a line midway between the bushing pin and the outer diameter of the bushing. When you apply force, the line should not be displaced more than 1/8-inch.

If the bushing is less than 1/4-inch, the movement must be less than half the elastomer material. If there is any sign of cracking or crumbling, replace the bushings. Bad bushings can cause good shocks to deliver a poor ride.

My personal preference is for urethane bushings. They deliver virtually the same ride, but are stronger and resist degradation better. Replacement bushings go on (or in) better if they are lubricated. Don’t use mineral oil, especially on rubber. Experts suggest using margarine as a lubricant. It’s vegetable based and won’t attack the bushings. Also, it’s easy to spread (pun intended). LL