G3500B Engines Caterpillar

The exhaust bypass valve is preset at the factory. However, adjustments may be necessary due to the following circumstances:

• Replacement of the exhaust bypass valve

• Altitude

• Changes in the ambient temperature

• Changes in the engine's load

Use the following procedure to adjust the exhaust bypass valve.

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Illustration 1	g00814530
(1) Plug (2) Locknut (3) Adjustment screw

1. Remove plug (1) and the seal. Loosen locknut (2).

2. Turn adjustment screw (3) clockwise for approximately four turns in order to remove the function of the exhaust bypass valve. Be careful not to tighten the screw too far.

3. Adjust the engine's exhaust emissions according to Systems Operation/Testing and Adjusting, "Air/Fuel Ratio Control - Adjust (Oxygen Feedback)".
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   Work carefully around an engine that is running. Engine parts that are hot, or parts that are moving, can cause personal injury.

4. After the desired exhaust emissions are obtained, slowly ramp up to 100 percent load or to the maximum available load.
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   Illustration 2	g01097923
   Open position of the compressor bypass valve in percent versus engine load in percent (X) Engine load in percent (Y) Open position of the compressor bypass valve in percent (1) 100 percent of load equals an open position of 18 percent for the compressor bypass valve.

5. Refer to Illustration 2. Determine the engine's load. Turn adjustment screw (3) in order for the "Bypass Valve Position" to be correct for the engine's load. Turn the adjustment screw counterclockwise in order to decrease the open position of the compressor bypass valve. Turn the adjustment screw clockwise in order to increase the open position of the compressor bypass valve.

6. When the value of the "Bypass Valve Position" is correct, tighten locknut (2) to the torque that is listed in the engine's Specifications.

7. Install the seal and plug (1).