Chevy 305 Engine Rear Main Bearing Replacement Repair Guide

Difficulty

Moderate

Steps

Time Required

                          1 - 3 hours

Sections

Rear Main Seal
4 steps
Rear Main Bearing
1 step

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Introduction

The rear main bearing is located under the same cap as the rear main seal. This rear main bearing goes between the cap and the crank case in order to ensure a smooth, frictionless surface to the crankcase to rotate inside of.

What you need

Step 1

              Rear Main Seal

Remove the 18 bolts holding the oil pan in place using the 3⁄8 and 1⁄2 sockets, 6 inch extension and 3⁄8 ratchet.
Fourteen 3/8 bolts around the perimeter and four 1/2 bolts on each corner.
Lift the oil pan up and forward so the oil pump pick up will clear the baffle.
Do not remove the oil pan gasket yet.

Remove the 18 bolts holding the oil pan in place using the 3⁄8 and 1⁄2 sockets, 6 inch extension and 3⁄8 ratchet.

Fourteen 3/8 bolts around the perimeter and four 1/2 bolts on each corner.

Lift the oil pan up and forward so the oil pump pick up will clear the baffle.

Do not remove the oil pan gasket yet.

1024

Step 2

Remove the single 9/16 bolt holding the oil pump in place and pull straight up from the base of the oil pump to remove.
Using a rubber mallet to break loose, gently tap on the side of the base of the pump indicated by the arrow. DO NOT HIT THE TOP OF THE PICK UP TUBE AND SCREEN. This can potentially damage the pick up tube or screen.

Remove the single 9/16 bolt holding the oil pump in place and pull straight up from the base of the oil pump to remove.

Using a rubber mallet to break loose, gently tap on the side of the base of the pump indicated by the arrow. DO NOT HIT THE TOP OF THE PICK UP TUBE AND SCREEN. This can potentially damage the pick up tube or screen.

Step 3

Remove the six 11/16 flywheel bolts using the 11/16 socket.
The breaker bar may be needed to break these bolts loose
This provides more room to access the rear main cap.

Remove the six 11/16 flywheel bolts using the 11/16 socket.

The breaker bar may be needed to break these bolts loose

This provides more room to access the rear main cap.

Step 4

Remove the two 5/8 rear main cap bolts. Gently tap the side of cap with a rubber mallet if needed to break free.
Remove the rear main seal. The upper half of the seal can easily be removed by hand.
Loop the new bottom half of the seal through the slot indicated in picture.
Needle nose pliers may make this easier but be cautious not to handle the new seal too aggressively so you do not damage it .
Put the rear main cap back and torque to specs (65 ft.-lbs.) followed by the oil pump and torque to specs (60-70 ft.-lbs.)

Remove the two 5/8 rear main cap bolts. Gently tap the side of cap with a rubber mallet if needed to break free.

Remove the rear main seal. The upper half of the seal can easily be removed by hand.

Loop the new bottom half of the seal through the slot indicated in picture.

Needle nose pliers may make this easier but be cautious not to handle the new seal too aggressively so you do not damage it .

Put the rear main cap back and torque to specs (65 ft.-lbs.) followed by the oil pump and torque to specs (60-70 ft.-lbs.)

Step 5

              Rear Main Bearing

Remove the rear main bearing and replace.
Liberally apply assembly lubricant/oil to the new bearing surfaces and crankshaft journal.
Gently tap the cap against the engine block or use thin flathead to remove.

Remove the rear main bearing and replace.

Liberally apply assembly lubricant/oil to the new bearing surfaces and crankshaft journal.

Gently tap the cap against the engine block or use thin flathead to remove.

To reassemble your device, follow these instructions in reverse order. Torque rear main cap bolts to 65ft.-lbs. Torque oil pump bolt to 60-70ft.-lbs. Torque oil pan bolts to 12ft.-lbs.

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                    Joey Barton

Member since: 10/30/2019

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                       University of Memphis, Team S4-G3, Kim Fall 2019                        

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Introduction

What you need

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