Usage:
Introduction
The 1991 OR-3325, OR-3326, OR-3327, OR-3380, and OR-3533 Remanufactured Truck Engines have a tuned or divided inlet air system REQUIRING a dual pipe assembly to the engine from the charge air core (CAC).
GM/Chevrolet and other truck manufactures using the 3116 Truck Engine supply the dual CAC pipes.
The 1991 OR-3325, OR-3326, OR-3327, OR-3380, and OR-3533 Remanufactured Engines are equipped with the air inlet for GM TopKick and Chevrolet Kodiak Trucks.
NOTE: Refer to the Parts Manual for other applications (Engine Arrangements) for the correct tuned engine air inlet elbow.
The 1991 OR-3325, OR-3326, OR-3327, OR-3380, and OR-3533 Remanufactured Truck Engines being installed MUST use a tuned inlet system for correct performance and emissions.
The part number for the individually tuned pipes for 1991 engines (7HJ, 2BK) must be obtained from the truck manufacturer except for GM TopKick and Chevrolet Kodiak Truck applications listed in the following chart.
The part numbers in the following chart are major parts that MUST be changed/installed when installing a 1991 (2BK)) in place of the original 1990 (7SF) engine in a GM TopKick or Chevrolet Kodiak Truck.
Part Description and Installation Recommendations
Exhaust Pipe Connection and Relocation
The exhaust connection of the 1991 wastegate turbocharger connection is approximately 33.02 mm (1.300 in) to the rear, compared to the 1990 turbocharger.
The exhaust piping MUST be loosened and MOVED to the rear approximately 33.02 mm (1.300 in) or SHORTENED approximately 33.02 mm (1.300 in) depending on the exhaust piping design.
Horizontal Position Exhaust Piping
The exhaust piping MUST be loosened an MOVED to the rear approximately 33.02 mm (1.300 in).
Vertical Position Exhaust Piping
The exhaust piping MUST be shortened approximately 33.02 mm (1.300 in).
Inlet Heater Relay Switch
The 1990 and 1991 engines do NOT use the same design inlet heater relay switch connectors:
1990 Engine Heater Relay Connectors
The 1990 engine heater relay has two terminal bolts with nuts and the GM/Chevrolet wiring harness has eyelet type connectors.
1991 Engine Heater Relay Connectors
The 1991 engine heater relay has standard GM (Packard) connectors as part of the relay.
When installing the 1991 engine, cut the eyelet-type ends off the two-wire GM/Chevrolet harness and permanently splice in a 4P-7211 Wire Assembly.
NOTE: The relay is NOT polarity sensitive, but the splice locations MUSTbe insulated.
The 4P-7211 Wire Assembly has the correct GM/Chevrolet two-wire connector to fit the matching connector on the 1991 engine.
Engine Heater Relay Switch Location
The relay switch is located on the right side of the engine, just behind the air inlet elbow.