Techs mechs

Engine makers talk a lot about time-to-overhaul, an interval approaching or even exceeding a million miles for many models. If only everything on the engine would last that long. The most nagging problem this time of year? Water pumps.

But before you utter a few choice words and yank yours out, make sure it’s actually failed. According to the Technology and Maintenance Council of the American Trucking Associations, the high priests of truck maintenance, it’s safe to declare a water pump dead or dying when seepage is spotted at the pump’s weep hole. In fact, the hole is there to allow a bit of moisture to escape from the unit, so a few drips of coolant may be normal. Steady dripping, on the other hand, indicates an internal seal failure and the unit may indeed be bad.

Seal failures are just one reason pumps fail. Dirty and rusty coolant, and too little or too much supplemental coolant additive (SCA), can turn the coolant into a brine that will destroy the pump. How do you avoid that? Here are four ideas:

1Use the right antifreeze. Engine builders publish recommendations on what to use, so ask your dealer for the recommendations and follow them. Don’t use consumer-type antifreeze formulated for cars and light trucks. The overdose of silicates will create a green goo that damages the parts in heavy truck diesels.

2When you use SCAs, stick to the engine builder’s guidelines. SCAs can be poured into the coolant or released gradually by special equipment, including filters. Ask about installing a coolant filter if your truck doesn’t have one, and if it does, keep it working.
3Avoid hard water and water that runs through galvanized iron pipes.

4Monitor the coolant’s condition by visual and chemical inspection. Look for rust, dirt and discoloration. Periodically sample and analyze the coolant to find out exactly what’s in there, and then drain the old coolant at the engine builder’s recommended interval (for example, every 200,000 miles). Flush the system and refill it with the right stuff. It’s cheaper than replacing the pump.

If you take care of the cooling system at large, the pump will last a long time. If you don’t, you may find yourself at the end of a wrecker’s hook, uttering a few choice words.