1 Answer

Oil pan.

Instructions
1
Drive your GMC Sierra up onto ramps or lifts so you have room to work as you pull out the oil pump. You could also use a jack, but make sure you brace the front wheels so they don't roll. In addition, set the emergency break firmly into position so the car doesn't roll.

2
Find the oil pan on the bottom of your engine and remove it. Take off the oil pump mounting bolt and take out the oil pump.

3
Clean the surrounding cables with water and old rags to avoid corrosion from salt and other road maintenance substances as well as dirt. Inspect your oil pump locator pins, looking for damage. Replace damaged components.

4
Put your new oil pump on the locator pins and install. Tighten the oil pump bolt to 66 ft-lb. Put the oil pan back on.

5
Turn the car on and check for leaks around all the parts replaced. Drive your GMC Sierra off the lifts if there are no leaks.

Read more: How to Replace an Oil Pump in a GMC Sierra | eHow.com http://www.ehow.com/how_4506342_replace-oil-pump-gmc-sierra.html#ixzz2HDe80YKL