OEM GMC Sierra 3500 Classic Oil Pan

GMC Sierra 3500 Classic Oil Pan Parts Questions & Experts Answers

• Oil Pan
  12599806
  Q: How to replace the oil pan on 4WD on GMC Sierra 3500 Classic?

  A: First, raise and support your vehicle when replacing the Oil Pan on 4wd vehicles. You need to remove skid plate bolts and skid plate when working on 1500 series vehicles. The Oil Pan skid plate bolts on the vehicle's rear need loosening but the front bolts and skid plate should be removed if installed. Start by placing a suitable drain pan underneath the Oil Pan Drain Plug (430) before you remove the Drain Plug. Allow all oil to drain out before reinstalling the Drain Plug tight. A drain pan goes under the Oil Filter before you remove it at point (437) so the filter can empty before you put the filter back properly. For both 1500 and 2500 series vehicles extract the right and left side transmission cover bolts and cover before removing the crossbar bolts/nuts and crossbar. When working with 4l60-e/4l70-e automatic transmissions you should remove the two lower transmission bolts. For 4l80-e, remove the 2 lower transmission bolts; the transmission lower bolts are to be removed for 4l80-e but for 6l80-e only the left bolt and right stud need to come out. Disconnect the engine harness electrical connector from the oil level sensor then remove the engine harness clip from the transmission oil cooler line bracket before removing the battery cable channel bolt. Reposition the channel pin from the Oil Pan tab while removing compatible oil cooler lines from the transmission-specific clip. Begin by removing the fasteners of the transmission oil cooler line clip from the Oil Pan before moving onto Oil Pan bolts followed by the pan's removal. Before pan reuse, users must drill out Oil Pan Gasket rivets when needed before removing both the gasket itself and its rivets. The first step for installation requires critical alignment of the structural Oil Pan followed by strict avoidance of gasket reuse during assembly. Place a new Oil Pan Gasket onto the Oil Pan followed by a 5 mm (0.20 in) bead of sealant on the front and rear cover engine block gasket tabs before installing the Oil Pan and its bolts to a snug torque. When installing the lower right transmission stud together with the lower left transmission bolt you should tighten them until they become snug on vehicles with 6l80-e automatic transmission. Snap the transmission bolts into place until they reach a snug fit for 4l80-e along with 4l60-e/4l70-e. The tightness of both the Oil Pan bolts and the front cover bolts to 25 n.m (18 lb ft) and the rear cover bolts to 12 n.m (106 lb in) and the transmission bolts/stud to 50 n.m (37 lb ft) is required. Next attach the transmission oil cooler line clip before installing its bolt to the Oil Pan while maintaining a torque of 9 n.m (80 lb in). Secure the oil cooler lines to the installation clip first then position the channel and slide the channel pin into the Oil Pan tab. Last, install the battery cable channel bolt and tighten it to 12 n.m (106 lb in). The oil level sensor needs its electrical connection from the engine harness while the engine harness clip must mount at the transmission oil cooler line bracket. Both 1500 and 2500 versions require cleaning all original adhesive traces while distilling the bolt threads with denatured alcohol followed by an application of gm p/n 12345493 threadlock (Canadian P/N 10953488) or its equivalent to the bolts. For 2500 series vehicles torque nuts to 120 n.m (89 lb ft) while 1500 series requires 100 n.m (74 lb ft) torque. Secure the left side transmission cover in position then install its bolt before tightly torquing it to 12 n.m (106 lb in). Finish by installing the right side transmission cover bolt. Routine use of the original Oil Pan requires replacing the Oil Filter with a new one using clean engine oil to lubricate the seal then securing it at 30 n.m (22 lb ft). Reinstall the front differential carrier followed by steering rack installation and bolting. Tighten left side bolts to 200 n.m (148 lb ft) while right side bolts require 100 n.m (74 lb ft). On 2500 series vehicles position the Oil Pan skid plate then install the 2 front Oil Pan bolts if equipped; tighten all bolts including the 2 rear Oil Pan bolts to 28 n.m (21 lb ft). The Oil Pan skid plate requires mounting on 1500 series vehicles while torqueing the bolts to 28 n.m (21 lb ft). Drop the vehicle before filling its engine with new engine oil and check for fluid leaks with the engine operating.