Why Coolant Hoses Fail

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    Mark Rahn
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    Tech Tips by Chris Trautman http://www.corvette-web-central.com

    This is a great article on why coolant hoses fail. The point I want to stress is the quality of the parts we buy for our Corvettes can vary greatly. Just because things look the same does not always mean they are. The use of inferior materials and low tech production processes often means the difference between a few dollars in savings to the customer. Competition is the driving factor for manufactures when making replacement parts. Being the lowest price can often be the only goal for these companies. Quality parts will almost always cost more. So how do you know what quality a part is? When shopping for parts look for warranty information. Often this is an indicator of how the manufacturer stands behind its product. If they know it’s going to fail at a higher rate they may only put a 1 year warranty on it. ACDelco parts are almost always the same or better OEM manufacturing standards as what came on our Corvettes from the factory.
    On a side note: One of the biggest differences between aviation and automotive parts manufactures are the standardization of parts. In the aviation world replacement parts are federally regulated to meet a set standard or TSO. A TSO is a minimum performance standard for specified materials, parts, and appliances used on civil aircraft. When authorized to manufacture a material, part, or appliances to a TSO standard, this is referred to as TSO authorization. Every single part installed on all airplanes starts life living to this standard. Anybody can make the part as long as they do it to that standard. This is also one of the reasons why airplanes cost so much!
    Chris Trautman

    Checking Coolant Hoses and
    Why they Fail
    By: Mike Militello from AC Delco Tech Connect
    What is the best way to check the condition of the coolant hoses on an engine? If you answered X-ray vision, you’re right. That would allow you to see inside the hose to view the tiny cracks on the inside walls of the hose where damage begins. The second best, and more realistic way, to check any coolant hose is with the squeeze test. The squeeze test can be used to inspect any coolant hose for the negative effects of Electro Chemical Degradation (ECD), which is the primary culprit of coolant hose failure. ECD creates fine cracks, or striations, in the tube wall inside the hose. The fine cracks extend from the inside to the outside of the hose tube near one or both ends of the hose and weaken the structure of the tube.
    Regular Maintenance
    Evidence of ECD depends on the quality of the hose, time and vehicle use, so there is no readily identifiable maintenance interval to follow. The squeeze test of coolant hoses should be included as part of a vehicle’s regular maintenance. To perform a squeeze test, squeeze the hose near the clamps or connection using the following procedures:
    • Make sure the engine is cool
    • Use your finger and thumb, not your whole hand, to check for softness
    • Squeeze near the connections. ECD occurs within two inches of the ends of the hose, not in the middle.
    • If the ends feel soft or mushy but the middle feels firm, the hose is under attack from ECD
    Electro Chemical Degradation
    ECD is an electrochemical attack on the tube compound. Different metals found in an engine system release an ionic discharge, generating 5 to 150 millivolts. The coolant contacts the various metals, picks up the charge and discharges the electrical energy into the hose. The voltage discharge initiates an electrochemical process that ultimately creates small cracks or striations (markings with parallel grooves) in the hose tube. Over time, these cracks widen, resulting in pinhole leaks and, eventually, leading to catastrophic failure. Heat does not cause the failure, but it does accelerate the electro chemical degradation process.
    Inferior hoses are more susceptible to ECD. It is recommended to change these hoses every four years or sooner if used in a fleet application. Some standard hoses have revealed damage and failures as early as 20,000 miles in fleet applications. To beat the effects of ECD, a new innovative tube material has been developed that is Electro Chemically Resistant (ECR). In testing, the ECR hose has been shown to last 200,000 miles. In addition to ECD damage, during a routine inspection of coolant hoses, always check for any heat damage, oil damage, and abrasive ozone damage (caused by pollution attacking bonds in rubber components that appears as tiny cracks at curves and bends) of the hoses.
    How to Replace the Heater Hoses in a Chevy Corvette By – http://www.ehow.com/ Friday, August 10, 2012 By an eHow Contributor
    The two rubber hoses attached to your Chevy Corvette’s heater core are heater hoses. They route coolant to and from the core to warm your car interior. Replace heater hoses occasionally to keep your engine system running smoothly. Heater hose maintenance prevents leaks, overheating and other problems that may plague your Corvette.

    Instructions
    o 1Turn off your engine and locate the heater hoses. The Corvette hoses connect to the heater core on the passenger side of the car.
    o 2Drain the Corvette system of coolant by opening the petcock on the radiator and allow it to flow into a drain pan. Keep coolant in a sealed container before throwing it away. Cats and dogs like the smell of coolant, so keep your pets locked out of the garage when changing heater hoses.
    o 3Remove old clamps with pliers or a screwdriver. Take out the old heater hoses by cutting them with a razor blade and then lift the hoses out of the passenger side engine compartment.
    o 4Measure the length and inside diameter of the old heater hoses if you choose to buy a store brand from an auto parts supplier instead of a dealer item to ensure that you purchase the correct replacement hoses.
    o 5Clean the clamp fittings with a multipurpose solution. Then apply gasket sealer to make sure the clamps and new hoses fit securely.
    o 6Push the clamps over the new heater hoses. Add fresh coolant to the radiator and be certain that the radiator is at least half full of coolant to maintain proper operation of your Corvette. o 7Start the engine and check for leaks. If you don’t see any leaks, then you’ve successfully replaced the heater hoses and they will function properly.
    Read more: How to Replace the Heater Hoses in a Chevy Corvette | eHow.com http://www.ehow.com/how_4508627_replace-heater-hoses-chevy-corvette.html#ixzz23438q8LX

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