HIGH TEMPERATURE OR OVERHEAT CONDITION
VEHICLES AFFECTED: 1982-85 C/K 2,3 Trucks Built Before January 1, 1985 With 7.4L (454) Engines ---------------------------------------
This bulletin is being released to provide information for adding an electric cooling fan that will provide additional cooling to 1982-1985 C/K models with the 454 engine. This information is a supplement to Product Service Bulletin 84-6-286 dated July 22, 1985, and is not intended to replace that bulletin.
Effective January 1, 1985, trucks built with the 454 engine and H5D emissions equipment are also built with an electric cooling fan. This fan is designed to provide additional cooling at low speed vehicle operations, at extended idle, and stop and go traffic conditions, etc.
If a vehicle has a low speed overheat condition and has been modified using the information in Product service Bulletin 84-6-286, and additional cooling is required, use the following information and illustrations to install the electric cooling fan.
Parts information -
Quantity Part Number Description -------- ----------- ----------- 1 15593566 Electric Fan 1 14078902 Fan Relay 1 14080661 Temperature Sender 1 12064526 Harness Assembly 2 15599042 Bolts - Relay 4 22527475 Bolts - Fan 10 11501906 Tie Wraps
Instructions -
1. Disconnect the battery cable.
2. Remove the grill assembly.
3. Set fan in position and mark the location for mounting screws. Remove the fan and drill holes for fan mounting.
CAUTION
MUST BE TAKEN NOT TO ALLOW THE DRILL TO HIT THE AIR CONDITIONING CONDENSER OR RADIATOR.
Use either a drill depth guide or wrap tape around the drill bit for a STOP (See Figure 1).
4. Install the fan assembly (See Figure 1).
5. Drain the cooling system.
6. Install the fan relay (See Figure 2).
7. Install harness (See Figure 2). Make sure the harness is fastened to the fender and the radiator support and away from sharp edges.
8. Install sender in the right cylinder head (See Figure 3).
9. Route the fan harness along side of the engine harness and attach to distributor, junction block, and to the engine temperature sender. Fasten the harness to the engine harness with the wraps (See Figures 4 and 4A).
10. Refill the cooling system.
11. Reconnect the battery cable.
12. Start the engine, idle, and test the function of the cooling fan (make sure fan is blowing air through radiator, if fan is blowing in the reverse direction, switch the wires in the fan harness connector at the motor). The fan should come on when engine reaches about 107 degrees C to 115 degrees C (225 degrees F to 240 degrees F).
13. If the fan checks OK, reinstall the grill and check for any coolant leaks.
Labour Time to perform this procedure is 1.2 hours.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
