CONTROL GP-GOVERNOR 9N2145 - Caterpillar

3406B Truck EnginesReference: 3406B Service Manual, SEBR0544-02, Disassembly and Assembly Module, Pages 6-108 through 6-110 for valve springs only. Special Instruction SEHS9032, "Using The 1U9347 Valve Spring Compressor Group". Caterpillar has accommodated use of the Williams Blue Ox® 485 kPa (70 psi) Exhaust Brake on any 3406B Truck Engine. Since this exhaust brake causes a higher exhaust back pressure than other exhaust brakes used on 3406B Truck Engines, larger exhaust valve springs and associated parts must be used when it is installed. To meet this requirement, a 9Y6712 Exhaust Brake Conversion Group must be installed at the same time. This group consists of:
12-9Y3326 Outer Spring (Exhaust Valve)12-9Y3327 Inner Spring (Exhaust Valve)12-9Y3328 Washer12-9Y3329 Rotocoil Assembly24-2A4429 Lock (Keeper)The standard springs can be removed and the larger springs installed with the engine in the chassis and the head on the engine. For earlier engines with the pre-combustion-type DI fuel nozzle adapter, use either the FT1887 Compressor Plate Group as shown in the referenced Service Manual, or the new 1U9347 Spring Compressor Group to compress the springs. The Special Instruction shows how this new tooling is used.
Most engines have the later, tall nozzle adapter. For these engines, only the new 1U9347 Spring Compressor Group can be used.
If the head is off the engine, use a conventional spring compressor.
The only orifice size Caterpillar recommends for this brake is 17.48 mm (.688"), and it applies to any braking rpm up to 2200 rpm. A smaller orifice and/or higher operating speed will cause excessive back pressure and shorten the life of the valve train. If desired, a 7E0970 Cylinder Head Group (basic), which includes the parts in the 9Y6712 Conversion Group, can be ordered as a factory-installed attachment. This exhaust brake is not available as a factory-installed attachment.
Due to interference with the later valve rotators and the Jake® Brake bridge, the Williams Blue Ox® Exhaust Brake cannot be used in addition to the Jake Brake to improve braking capacity.