The Vortec 4.8-liter engine comes standard in the Yukon and Tahoe full-size SUVs. It is also optional in the Sierra and Silverado pickup trucks. The Vortec is matched with GM's Hydra-Matic 4L60 transmission, a four-speed automatic, in the Yukon and Tahoe. The Silverado and Sierra models team the Vortec engine with the 4L80 transmission. It is a Gen IV block that has a 90-degree cylinder angle and 4.4-inch bore centers -- the only two things that remain the same in GM's older small-block V-8s and the newer V-8s.
Open the hood and locate the knock sensor on the side of the engine block. The knock sensor is a round metal part. The top of the sensor, just under the wiring harness connector, is hexagon-shaped, so you can turn it with a wrench.
Detach the knock sensor's wiring harness connector by pulling the plug off the sensor.
Fit the wrench around the hexagon shape on the sensor and turn the sensor counterclockwise to remove it from the block.
