1990/02/01 Caterpillar

3306B (63Z) And 3406B (4MG) Truck Engines

An improved 1W2076 Cover is used in the fuel ratio control groups. Effective with 3306B Truck Engines 63Z7937-15121, and 3406B Truck Engines 4MG3600-58752, the 1W2076 Cover in the fuel ratio control group was made from zinc. Formerly, the cover was made from aluminum. The cover made from zinc can distort when exposed to heat and pressure. This distorting can cause the cover mounting bolts to loosen and allow the gasket under the cover to blow out. This can result in an engine performance complaint. The zine cover should be replaced with an aluminum cover. An FT1906 Fabricated Tester and a soap solution can be used to check for leaks.

Location of the 1W2076 Cover on the fuel ratio control group.

Effective with 3306B Truck Engine 63Z1 5122 and 3406B Truck Engine 4MG58753, the 1W2076 Cover is again made from aluminum. The improved aluminum cover is stronger and will not distort. The aluminum and zinc covers look the same. The difference can be detected by weighing the covers. The aluminum cover weighs 57 g (2 oz), while the zinc cover weighs 113 g (4 oz).

Dealers in NACD, COSA, and Caterpillar Americas can order drawings of Fabricated Tools (FT) from the address that follows. When ordering, be sure to include your dealer code and address so your request will receive immediate attention. All other dealers can order drawings from their Subsidiary Service Departments.