2004/04/05 Caterpillar

High Boost Pressure Events in Cold Weather {1057}

Usage:

793C 4AR

Off-Highway Truck/Tractor: 793C (S/N: 4AR1-UP; ATY1-UP; 4GZ1-UP)

For the applications that are listed above, unnecessary engine derates have been experienced. During cold weather, engine operation on steep grades and under certain engine load conditions may trigger a high boost pressure event that will derate the engine.

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Illustration 1	g01064523
(1) Valve stop (2) 9P-8217 Washers (3) Spacer

In order to prevent this derate, install two 9P-8217 Washers (2) between valve stop (1) and spacer (3) on the wastegate control valve. Refer to Illustration 1.

Note: Do not install the washers unless 1143 High Boost Pressure Events, that are followed by 1179 Engine Derates are documented during the conditions that are mentioned above. Ensure that the wastegate control valve and all other air system components are functioning properly prior to performing this procedure.

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