Usage:
3406B Truck Engines
Reference: This article supersedes a previous article in Service Magazine; December 25, 1989; Page 7; /bq/New Valve Assembly And Washer Used In Fuel Transfer Pump Group" on 3406B Truck Engines.
Description of Change: Three new valve assemblies and a spacer are used in the fuel transfer pump group. The new valve assembly is made of a low carbon steel cage, wrapped around a die cast aluminum body with a hytrel rubber disc. The new valve assembly will not work loose due to material yield. It will provide a better press fit due to the thicker flange and the closer tolerance on the outside diameter. The new spacer is thinner than the former spacer to accommodate the thicker valve, thus keeping pump pressure the same.
Adaptable To: The part number of the improved 1W1700 Fuel Transfer Pump Group has not changed. The new 7E2464 Valve Assembly (1) replaces the former 7W8412 Valve Assembly. The new 7E3667 Spacer (2) replaces the former 7C0396 Spacer. The new valve assembly and spacer are effective with 3406B (4MG75785, 8TC9747) Truck Engines. The new valve assemblies and spacer, when used together, are adaptable to earlier engines. Before installing a new valve assembly do the following:
1. Check the bore where the valve assembly is installed in the fuel transfer pump housing. Bore diameter (A) must be 25.335 ± 0.025 mm (.9974 ± .0010"). See Illustration 1.
Illustration 1. Bore diameter (A).
2. If a 7E4656 Retainer has been installed during an earlier rework, it must be removed and discarded when the new valve assembly is installed.
Illustration 2. Location of components.
The new valve assembly can be identified by seven holes in the body, where the former valve assembly has a cross bar on the valve boby.