A New Inlet Manifold Air Temperature (IMAT) Switch Is Now Used on Certain G3412 Generator Set Engines {7400, 7418} Caterpillar

Engine

G3412 (S/N: R7A1-UP; KAP1-UP)

G3412C (S/N: SPY1-UP)

Description Of Change: The new IMAT switch has been improved by increasing the length to provide more of an accurate temperature reading. The new IMAT will prevent erroneous SP1 faults (shutdown due to high IMAT).

Adaptable To: The new 146-1762 Temperature Switch replaces the existing 212-7246 Temperature Switch. The new temperature switch is adaptable to the above engine back to first production.

Installation Procedure

Note: An adapter will be required to install the 146-1762 Temperature Switch since the thread size on the new switch does not match the thread size of the existing aftercoolers. Also, there are two different styles of aftercooler housing. Both currently use the 212-7246 Temperature Switch, but in different locations.

Parts Needed

Procedure

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Illustration 1	g06104210

1. Remove existing 212-7246 Temperature Switch, and adapter if applicable. Install 3K-0360 O-Ring Seal onto 146-1762 Temperature Switch. Refer to Illustration 1.
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   Illustration 2	g06104240
   (A) Switch Location in Rear of Engine

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   Illustration 3	g06104225
   (B) Switch Location in Rear of Engine (Close Up) (C) Adapter

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   Illustration 4	g06104251
   (D) Switch Location in Front of Engine.

   Note: This application does not include the old 1L-5620 Adapter, but will require the new 500-4238 Adapter.

2. Install 500-4238 Adapter using appropriate thread sealant for NPT fittings. Install in either the engine front or rear location depending on aftercooler housing style. Install 146-1762 Temperature Switch into the adapter. Tighten IMAT switch to 82 ± 9 N·m (60.5 ± 5.9 lb ft).

This change is effective for the serial numbers listed in Table 2.