Big Rig Basics
Don’t Get Hosed
Coolant hoses are attacked by many under-hood forces. For this reason, they need to be inspected at every routine maintenance interval for your truck and replaced if they show damage.
1. Turn the engine off and let it cool until you can comfortably inspect the hoses. First, look at them for obvious signs of trouble:
If you see a leak, most often occurring where the hose is connected to an engine or radiator fitting, make a note of it. The best fix is normally to replace the hose with a new one (unless it is obvious that it is in very good condition) and make sure it is clamped properly.
Oil causes the hose to lose strength and swell to form a bulge. Repair the oil leak on the engine, then replace the hose.
The outside cover of this hose has been damaged by rubbing something in the engine compartment. Replace the hose and reroute it or protect it so it won’t be damaged again
There isn’t much you can do about ozone, but because the outside cover no longer seals the hose from further damage, it should be replaced.
2. Once the visual inspection is complete, check each hose out by feel. Squeeze the hose 2 to 4 inches from the ends where it is connected. Feel for softness by comparing these areas with the middle, which may feel more solid while the ends feel mushy, a form of damage called EDC. Also feel for any stiffness or hardening, which results from heat deterioration. If there are any of these signs, replace the hose.
3. To replace the hose, first drain the coolant into a clean container, then loosen the clamps completely and slide the hose off its fittings.
4. Inspect the fittings on either end to make sure they are free of high or flat spots, damaged beads and dirt, and not distorted. Make sure you have the right hose — one that will fit snugly around the fitting.
5. Place the clamps over the hose. Then install the hose onto the fittings, if necessary using water or a weak soap and water solution as a lubricant, until it is fully onto the fitting. It must touch any limiting stops on the fittings or sit two clamp widths past any beads. Then install the clamp so it will be straight and one band-width or about 1/4 inch from the end of the hose.
6. Torque constant torque-type clamps to specification with an inch-pound torque wrench. T-bolt type clamps must be of the proper size so that, when properly torqued, the gap between the loops at the ends of the band is 0.19 to 0.75 inch. Refill the cooling system.
7. If a hose leaks coolant when the engine is cold, ask the counter person about special plastic clamps installed with heat that expand and contract with temperature.
If you do these things, including checking the hoses at about every second oil change, you should be able to keep blown radiator and heater hoses from stopping you when on the road.
We thank Matt Duvall, heavy-duty product manager at Gates Corp. for providing information as to how hoses can be inspected and problems diagnosed, and for a number of illustrations. We also thank FlexFab LLC’s Bill Morrissey, heavy-duty truck sales manager, for providing further information on hose inspection, along with a copy of the Technology and Maintenance Council’s Recommended Practice 332, which provides hose installation guidelines.