1984/01/18 Caterpillar

Cooling system conditioner must be added to cooling systems to help prevent cylinder wall pitting. This pitting is a result of cavitation and corrosion.

How Cavitation Occurs

When an engine operates, the cylinder wall flexes (moves). This causes small air bubbles to form on the coolant side. When these bubbles collapse (explode inward), they remove a protective oxide film. Corrosion occurs when this film is removed. Corrosion causes wear and pitting. This pitting is called cavitation. The correct conditioner helps prevent this problem. Once cavitation damage has occured, incorrect levels of cooling system conditioner can cause pitting to get worse. These pits can eventually become holes in the cylinder wall. Holes let coolant into the combustion chamber which can cause major engine damage.

Add Cooling System Conditioner

Cooling system conditioner must be added to the water or the water/antifreeze solution to prevent pitting damage. Most antifreeze solutions do not have enough corrosion inhibitor to prevent this problem. Also, many Original Equipment Manufacturers do not add the correct cooling system conditioner to the cooling systems in their engines. Thus, it is important to check the cooling systems in all new engines. Different tests can be made to check the inhibitor concentration in the coolant mixture.

The L.O.C.C. Corporation is equipped to check this concentration.

For more information write:

Fleetguard Distributors has a 3300846S Test Kit available. For more information write:

Remember, it is the user's responsibility to make sure there is cooling system conditioner in the system. He must also make sure that the levels of conditioner are correct. Cooling system conditioner is available in different quantities, as shown in the chart that follows.

Initial Fill

The first time the cooling system is filled, the concentration of conditioner must be 3-6%. This concentration is very important. If the conditioner is too concentrated, an insoluble salt (contaminant) will form. These salts can cause wear on water pump seal surfaces. Use .48 liters (1 pt) of cooling system conditioner per 15 liters (4 gal) of cooling system capacity (3% concentration) the first time the system is filled. Always clean the cooling system before you add cooling system conditioner to a used engine for the first time.

Maintain Correct Levels Of Conditioner

Cooling system conditioner must be added to the cooling system regularly. The corrosion inhibitors which coat (cover) the metal surfaces on the cylinder wall become less effective over a period of time. Add .48 liters (1 pt) of conditioner per 74 liters (20 gal) of cooling system capacity. This should be done at recommended intervals (usually the same as oil change intervals). See the Operation and Maintenance Guide for specific oil change intervals and cooling system conditioner recommendations. Make sure that every time the cooling system is cleaned, cooling system conditioner is added to maintain a 3-6% concentration.

Coolant Conditioner Elements

Coolant conditioner spin-on elements and mounting bases are available from Caterpillar. These elements can be used in place of liquid conditioner. However, coolant conditioner elements and cooling system conditioner liquid should never be used together. There are many different types of elements. Some are precharge elements which are used the first time the cooling system is filled, and others are used for maintenance. Special Instruction, Form SEHS7222, has more information on how to install these elements.

Elements can be identified by their part numbers or by length. Jacket water cooling systems on marine engines must use liquid cooling system conditioner rather than coolant conditioner elements.

Use The Right Element

Use precharge elements the first time the cooling system is filled. This ensures the correct concentration of conditioner. The element must be the correct size. If it is incorrect, it can put too much inhibitor into the system. A maintenance element does not have enough conditioner to protect the cooling system during this initial fill. When there is not enough conditioner in the system, some surfaces are not protected against corrosion and cavitation. Once the maintenance element is installed, it must be changed at regular intervals to maintain the correct conditioner level.

See the Operation and Maintenance Guide for the specific engine model or the Operator's Guide provided by the Original Equipment Manufacturer to find out the cooling system capacity. The chart that follows shows element part numbers for different cooling system capacities. The number of elements needed is listed after the part number.

One 9N3668 Base Assembly can be used for almost all cooling systems. Cooling systems with 116-165 liter (31-43 gal) and 166-244 liter (44-64 gal) capacities need two base assemblies. If a new engine uses an element and base assembly together, it will also need two 9N3666 Valve Assemblies. The valves allow you to change the conditioner element without loss of coolant.

The following chart lists publications which give more information on cooling systems.