Suburban 3/4 Ton 4WD V8-454 7.4L (1985)
Radiator Cooling Fan Motor: All Technical Service Bulletins
Engine - Overheated at Extended Idle or Low Speeds
NUMBER:
86-B-92
GROUP:
6D - Engine Electrical
DATE:
June, 1986
SUBJECT:
ENGINE OVERHEAT
MODELS:
1985 C/K 2500-3500 WITH LE8 (454), H5D HEAVY DUTY EMISSIONS AND ELECTRIC BOOST COOLING FAN
Some 1985 C/K 2500 - 3500 trucks equipped with the 454 engine, H5D heavy duty emissions, and the electric boost cooling fan may experience an
engine overheat at an extended idle or low vehicle speed operation (under 5 mph.)
FIGURE 1 - FAN HARNESS CONNECTOR LOCATION
This condition may be caused by the electric boost cooling fan running in the reverse direction. If this condition is encountered, test the fan to verify that
the airflow is toward the rear of the vehicle through the radiator. If the airflow from the
fan is toward the front of the vehicle, this condition can be corrected by reversing the wires in the fan harness connector. See Figure No. 1.
This condition was corrected production beginning with the following VIN breakpoints.
Flint
501986
St Louis
503471
505403
Janesville
506052
