2003/07/01 Caterpillar

Engine:

3508B (S/N: S2D1-UP; S2E1-UP; S2F1-UP; 2BM1-UP; 7SM1-UP; 3PS1-UP; 5PS1-UP; 1TW1-UP; 96Y1-UP; 69Z1-UP)

3512B (S/N: S2H1-UP; S2J1-UP; S2K1-UP; S2L1-UP; S2M1-UP; 8EM1-UP; 7HM1-UP; S2N1-UP; BRN1-UP; 4TN1-UP; 3RS1-UP; 2GW1-UP; 3ZW1-UP; 50Y1-UP; 66Z1-UP; 2EZ1-UP)

3516B (S/N: CDE1-UP; 4MJ1-UP; 8CN1-UP; 8KN1-UP; S2S1-UP; 3SS1-UP; S2T1-UP; S2W1-UP; 4BW1-UP; 3CW1-UP; S2X1-UP; S2Y1-UP; 72Z1-UP; 29Z1-UP)

Illustration 1	g01010227
Right side view of an engine with a shunt tank

Some 3500B marine engines are equipped with a 4P-5635 Tank. This component is part of the jacket water cooling system. Refer to Illustration 1.

Some engines may experience repeated overflow of coolant from the pressure cap of the shunt tank when the temperature of the coolant in the jacket water circuit increases to the normal operating temperature.

This condition has been traced to the lack of a vent hole in the filler neck of the shunt tank. The lack of a vent hole restricts the volume that is available for expansion of the coolant. This results in an overflow of coolant in an otherwise acceptable installation.

To prevent overflow of the coolant, a vent hole must be drilled through the filler neck of the shunt tank. Use the following rework procedure in order to drill a vent hole through the filler neck.

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Personal injury can result from hot coolant. Any contact with hot coolant or with steam can cause severe burns. Allow cooling system components to cool before the cooling system is drained.

Note: The shunt tank may need to be removed in order to accomplish this procedure.

1. Drain the coolant from the shunt tank into an appropriate container.

2. Remove the shunt tank, if necessary. If you do not remove the tank, disconnect the hose from the bottom of the tank. This will help prevent contamination of the cooling system.

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Illustration 2	g01009433
Shunt tank and a 4C-3846 Abrasive (Grinder Mounted Point)

3. Use a die grinder and a 4C-3846 Abrasive (Grinder Mounted Point) in order to create a ledge on the inside of the filler neck. The ledge must be at least 63.5 mm (2.50 inch) from the top of the filler neck. Refer to illustration 2. Place the ledge at any location around the diameter of the neck. Create a ledge that is deep enough to allow the tip of a 6.3 mm (0.25 inch) drill bit to set on the ledge.

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Illustration 3	g01009442
Shunt tank and a 6.3 mm (0.25 inch) drill bit

4. Connect a 6.3 mm (0.25 inch) drill bit to a die grinder. Place the tip of the drill bit on the ledge. Refer to Illustration 3. Drill a hole through the filler neck.

5. Flush the shunt tank in order to remove all of the metal particles.

6. If the shunt tank was removed, reinstall the tank. Connect the hose to the bottom of the tank.

7. Check the level of the coolant according to the engine's Operation and Maintenance Manual. Fill the system with coolant, as needed. Check for any coolant leaks and correct any coolant leaks.