GM Northstar case halves reseal
From Mechanical Database
RTV Sealant Procedure with Current Oil Distribution Plate
Models
- 1993 Cadillac Allante
- 1993-2002 Cadillac Eldorado
- 1993-2004 Cadillac DeVille, Seville
- 2004 Pontiac Bonneville G/XP
Notes on RTV sealant
- RTV silicone sealant is used due to its ability to withstand GM Powertrain’s most grueling sealing tests.
- You must use GM #12478521, not a substitute RTV.
- This required sealant comes in a caulk gun applicator with a pre-cut 3 mm metered nozzle.
- The cartridge contains 150 grams of sealant.
- Don’t try to save left over sealant; throw the cartridge away and use a fresh one for each job.
- Plan to work quickly once you’ve opened the applicator; you should have the component in place within 10 minutes .
Procedure
- Drain the engine coolant and engine oil from the engine.
- Remove the powertrain from the vehicle.
- Remove the drive belt.
- Remove the A/C compressor and set it aside.
- Remove the power steering pump and set it aside.
- Remove the engine from the transmission.
- Install the engine on an engine stand.
- Remove the components necessary to remove the oil pan and lower crankcase, including but not limited to the following:
- Generator
- Oil filter adapter
- Crankshaft balancer
- Engine front cover
- Engine front cover gasket Oil pump
- Lower crankshaft sensor
- Rotate the engine stand with the oil pan facing up.
- Remove the oil pan bolts.
- Remove the oil pan.
- Remove the gasket from the oil pan.
- Remove the oil suction tube bolt and nut.
- Remove the oil suction tube.
- Remove the main bearing bolts.
- Remove the crankshaft oil scraper plate.
- Remove the oil distribution plate bolts.
- Remove the oil distribution plate.
- Remove the crankcase perimeter bolts on the right side.
- Remove the crankcase perimeter bolts on the left side.
- Remove the lower crankcase by prying at the designated pry points.
- Remove the lower crankcase.
- Remove the upper-to-lower crankcase seals.
- Using a suitable scraper, clean the anaerobic sealant from the rail surfaces of the block.
- Using a suitable cleaning tool, clean out the anaerobic sealant from the engine block seal groove in the rail of the block.
- Using a suitable cleaning solvent, clean the anaerobic sealant from the rail surfaces of the block.
- Using a suitable scraper, clean the anaerobic sealant from the rail surfaces of the lower crankcase.
- Using a suitable cleaning solvent, clean the anaerobic sealant from the rail surfaces of the lower crankcase.
- Ensure the surfaces to be sealed are free of anaerobic sealant and free of any nicks, gouges or scratches. Repair or replace components as necessary.
- Inspect all components removed for serviceability. Repair or replace components as necessary.
- Place a 5 mm (0.197 in) spot of RTV sealant, P/N 12378521 (in Canada, use P/N 88901148) or equivalent, at the two points where the crankshaft rear oil seal meets the split line of the engine block.
- Completely fill and slightly overfill the engine block seal groove with a continuous bead of RTV sealant, P/N 12378521 (in Canada, use P/N 88901148) or the equivalent.
- Ensure the RTV sealant, P/N 12378521 (in Canada, use P/N 88901148) or the equivalent, bead is higher than the rail surface by 3 mm (0.118 in).
- Using a suitable tool, spread the sealant in the area near the oil drain back passages away from the oil drain back passages and towards the outboard edge of the rail surface.
- To prevent shifting of the lower crankcase, install one of the EN 46109 tools into a bolt hole in each rail.
- Install the cleaned lower crankcase onto the engine.
- Using a rubber mallet, gently tap the lower crankcase into position.
- Remove both EN 46109 tools.
- Loosely install the crankcase perimeter bolts on the right side.
- Loosely install the crankcase perimeter bolts on the left side.
- Using a small long blade screwdriver, clean out any sealant in the oil drain back passages.
- Using a NEW oil distribution plate, plate a 3 mm (0.118 in) wide bead (1) of RTV sealant, P/N 12378521 (in Canada, use P/N 88901148) or the equivalent, around the perimeter of the outer seal of the oil distribution plate place.
- Ensure the RTV sealant, P/N 12378521 (in Canada, use P/N 88901148) or the equivalent, bead is inboard of all the oil pan bolt holes.
- To prevent shifting of the oil distribution plate, install one of the EN 46109 tools into a bolt hole in each side of the lower crankcase.
- Install the NEW oil distribution plate.
- Remove both of the EN 46109 tools.
- Install the oil distribution plate bolts.
- Tighten the oil distribution plate bolts to 10 N·m (89 lb in).
- Using a small long blade screwdriver, clean out any sealant in the oil drain back passages.
- Pay close attention to the rear main seal drain back passage in the pictures below, if it is not cleared it will result in a blown out rear main seal.
- Install the crankshaft oil scraper plate.
- Install the main bearing bolts. Ensure the stud-head bolts used for the oil suction tube support bracket are placed in the proper position.
- Tighten the main bearing bolts in the proper sequence.
- First Pass: Tighten the main bearing bolts (1 through 20) to 20 N·m (15 lb ft) in proper sequence.
- Final Pass: Tighten the main bearing bolts (1 through 20) an additional 65 degrees in proper sequence using the J 45059.
- Tighten the crankcase perimeter bolts in the sequence shown.
- Tighten the crankcase perimeter bolts to 30 N·m (22 lb ft).
- Using a small long bladed screwdriver, verify that the oil drain back passages are clear of sealant.
- Lubricate the silicone seal in the oil distribution plate. With a twisting motion, install the end of the oil suction tube (2).
- Install the oil suction tube retaining bolt (1) and nut (3).
- Tighten the oil suction tube support bracket nut to 24 N·m (18 lb ft).
- Tighten the oil suction tube bolt to 10 N·m (89 lb in).
- Using a suitable cleaning solvent, clean the sealing surfaces and seal groove of the oil pan.
- Using a suitable cleaning solvent, clean the sealing surfaces of the oil distribution plate.
- Completely fill and slightly overfill the oil pan seal groove with a continuous bead of RTV sealant, P/N 12378521 (in Canada, use P/N 88901148) or the equivalent.
- Ensure the RTV sealant, P/N 12378521 (in Canada, use P/N 88901148) or the equivalent, bead is higher than the oil pan sealing surface by 3 mm (0.118 in).
- To prevent shifting of the oil pan, install one of the EN 46109 tools into a bolt hole in each side of the lower crankcase.
- Position the oil pan onto the lower crankcase.
- Remove both EN 46109 tools.
- Install the oil pan bolts.
- Tighten the oil pan bolts in the sequence shown.
- Tighten the oil pan bolts in sequence to 10 N·m (89 lb in).
- Clean off any sealant that has protruded to the exterior of the engine. Important: For detailed component and engine installation, refer to Engine Replacement Procedure in the Engine Mechanical subsection of the appropriate Service Manual or SI.
- Install the components removed.
- Remove the engine from the engine stand.
- Install the engine to the transmission.
- Install a NEW oil filter.
- Install the power steering pump.
- Install the A/C compressor.
- Install the drive belt.
- Install the powertrain into the vehicle.
- Refill the engine coolant and the engine oil.









