Usage:
3406, 3408 and 3412 Engines In All Applications
Reference: Please put marks through the articles "Maintenance Instructions For Coolant Conditioner Elements" on page 1 of January 18, 1978 Engine News and "Attachment Groups Put Corrosion Inhibitor Directly Into Cooling System" on pages 2 and 3 of February 8, 1978 Engine News, and make a reference to see this article.
Description of Change: Some conditions of operation have been found to cause pitting (small holes in the metal surface) from corrosion or cavitation erosion (wear caused by bubbles in the coolant) on the outer surface of the cylinder liners and the inner surface of the cylinder block next to the liners on the above engines. Correct maintenance of the cooling system can keep this type of damage to a minimum.
To give the cylinder block and liner surfaces maximum protection, a 3% to 5% concentration of liquid corrosion inhibitor, or .8 to 3.4 ounces of a dry inhibitor per gallon of coolant, must be present in the cooling system at all times.
Attachment groups are now available to give this type of protection. The elements used in these groups have a specific amount of inhibitor for acceptable cooling system protection. As water or coolant flows through the element, the corrosion inhibitor, which is a dry material, dissolves (goes into a solution) and mixes to the correct amount of concentration.
When a cooling system is first filled with new coolant or water, an element with more than normal amount of inhibitor (precharge) is used. At the first change interval, the precharge element is removed and an element with a normal amount of inhibitor (maintenance) is then installed to keep the corrosion protection at an acceptable level. After the first change period, only maintenance elements are installed to give protection to the cooling system. Use the chart that follows to find the correct precharge and maintenance elements and when to change them.
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Extended change periods, for the elements shown in the above chart, can result in the loss of adequate cooling system protection.
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The precharge elements will give the correct charge of 1.5 to 3 ounces per gallon in the cooling system when it is filled. The maintenance elements, and the correct change periods, will keep the corrosion inhibitor in the cooling system between a maximum charge of 3.4 ounces per gallon and a minimum charge of .8 ounces per gallon for a 2,000 hour maintenance period. After 2,000 hours of operation, the cooling system must be drained and filled again. This will prevent salt deposits in the cooling system caused by the evaporation (water goes to vapor) and addition of water to the system.
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Hot coolant will cause burns. Change elements only when the coolant is cold. Before the elements are removed, close the inlet and outlet valves to prevent the loss of coolant.
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Before an element is installed, make sure it is the correct element for that application. The elements have the part number on them for easy identification. If paint has been put on the elements, identification can be made by the length of the element. See the chart that follows:
An optional method to give protection to the cooling system is to use Dowtherm 209 antifreeze. No precharge element is needed when Dowtherm 209 is used. But because Dowtherm 209 does lose its ability to give protection, a maintenance element needs to be installed at every other oil change period. Use the 9N3717 Maintenance Element when Dowtherm 209 and water are used in the cooling system.
If water must be added to the cooling system on a daily basis, either the cooling system has a leak or too much water is added (overfilling). Both of these procedures dilute (make weaker) the concentration of inhibitor.
Adaptable To: The attachment groups are not available for parts service as groups, but the separate parts can be ordered. The parts will be listed under their group numbers in the Parts Book Microfiche. The parts will also be given in the parts books at the next revision. The groups are adaptable to the 3406, 3408 and 3412 engines as shown in the chart that follows:
The elements can be used on other engines if a mounting bracket is made. A 9N3668 Base Assembly and two 9N3666 Valve Assemblies will be needed. The chart that follows can be used as a selection guide for elements based on cooling system capacity.
INSTALLATION: For installation of the attachment group use SPECIAL INSTRUCTION, Form SEHS7222, Installation of Coolant Conditioner Group On Truck Engines, for a reference.