Proper Preparation, Prevents Poor Performance

Dan Sharron
Posted on October 1, 2002

Help to reduce road calls this winter with proper hose maintenance. As fall turns to winter and temperatures drop, hoses can become brittle, crack or bulge. What I am alluding to, when the temperature of the hose and coolant changes, the hose will expand and contract. It is especially susceptible to cooler ambient temperatures, as the cooler ambient air will keep the hose from being pliable it can create a leak.This is due in part to unseen cracks developing from the inside. A regular visual inspection is necessary, especially if the hoses haven’t been changed after three years. Your inspection should include feeling the hose to check for cracks and brittle or soft spots that can lead to bulging. If you see cracks on the outside of the hose or feel a soft spot, push your finger into it. As any questionable hose should be replaced, if your finger indents the hose material easily, replace the hose. If your replacing a hose, what about types of hose material? One way to avoid hose problems is use silicone hoses. Sure silicone hoses are more expensive, but if your looking to cut down on road calls then this is a good choice, plus they are guaranteed for the life of the bus and offer resistance to temperatures as low as -60F. Standard hoses are only reliable to -40F and can become stiff or brittle at low temperatures.

How about the Hose Clamp, and where do you place it?

This is an important part of installation to prevent failures. The clamp should be placed just behind the retaining ridge of the connector. -Placing the clamp in the correct location prevents coolant from entering the area between the clamping surface of the hose and the connector. If coolant is allowed to enter this area (due to the clamp being placed too far away from the retaining ridge) the coolant will turn acidic because it is not circulating. This will deteriorate the hose from the inside without anyone knowing, and the result, a service call at the most inopportune time.Next, how tight is tight enough? Don’t tighten the clamp until the hose material squeezes through the clamp slits. Tightening the clamp too much can cut the hose at the edges of the clamp. Tighten only enough for the clamp band to just indent the hose material. If the hose leaks chances are the surface of the connector is not clean.As they say, “an ounce of prevention is worth a pound of cure”. If your not already doing so, have your technicians inspect hoses during routine maintenance. Preventing a road call is a ton of cure!

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