Mitsubishi Engine >> MAIN BEARING BOLT TORQUE CAUTION ON MITSUBISHI 4/6 G ENGINES

Mitsubishi Engine >> MAIN BEARING BOLT TORQUE CAUTION ON MITSUBISHI 4/6 G ENGINES

Main Bolt Tightening Caution For
1992-1999 Mitsubishi 4G & 6G Series Engines

The AERA Technical Committee offers the following information for main bolt tightening caution on 1992-1995 Mitsubishi 4G & 6G series engines. Information previously published in the OEM service manuals was incorrect and the following specifications should be used. The information in TB 2039 has abeen updated and it should be destroyed, as it is no longer valid information.

To install non-elastic main bearing bolts, the following procedure is applicable to all vehicles/engine listed below.

Tighten the bolts on each main bearing cap equally until the specified torque is achieved. Use the bolt-tightening sequence shown in Figure 1 if applicable.


Years Models Engine Torque

1992-95 Mirage 4G1/1.5L 38 ft/lbs (53 Nm)
1992-94 Eclipse 4G3/1.8L 38 ft/lbs (53 Nm)
1992 Galant, Expo & Truck 4G6/2.0&2.4L 38 ft/lbs (53 Nm) SOHC
1992 Eclipse, Galant 4G6/2.0L 49 ft/lbs (68 Nm) DOHC
1992-95 Truck,Montero,Galant,
Diamante 6G7/3.0L 57 ft/lbs (79 Nm) SOHC
1993-95 Diamante Wagon 6G7/3.0L 57 ft/lbs (79 Nm) SOHC
1992-95 Diamante & 3000 GT 6G7/3.0L 67 ft/lbs (93 Nm) DOHC Non/Turbo
1992 3000 GT 6G7/3.0L 67 ft/lbs (93 Nm) DOHC Turbo
1993-95 3000 GT 6G7/3.0L 54 ft/lbs (74 Nm) DOHC Turbo
1994-95 Montero 6G7/3.5L 54 ft/lbs (74 Nm) DOHC Turbo

Elastic main bolt tightening (plastic-angle tightening method). Before reusing main bolts measure the shank lengths of ALL the main bearing bolts. If the measurement of 2.799 (71.100 MM) is exceeded or the bolt has visual damage REPLACE THE BOLTS. Measure from the tip to the shoulder under the bolt head (not to the shoulder of the washer) see figure 3.

To tighten elastic main bearing bolts using the plastic/angle tightening method; the following procedure is applicable to all the engines listed below.

1. Torque bolts (in sequence see figure 2) to specification 18 ft/lbs.
2. Using a breaker bar (not a torque wrench), tighten each bolt 90°.
3. Using a breaker bar (not a torque wrench), turn each bolt an additional 90°.

The following vehicles/engines use elastic main bearing bolts:

1993-95 Mirage 4G9/1.8L 18 ft/lbs (25 Nm) Plus 90°, +90°
1992-95 Expo LRV 4G9/1.8L 18 ft/lbs (25 Nm) Plus 90°, +90°
1993-95 Eclipse 4G6/2.0L 18 ft/lbs (25 Nm) Plus 90°, +90°
1993 Galant 4G6/2.0L 18 ft/lbs (25 Nm) Plus 90°, +90°
1993-95 Expo, Expo LRV,
Truck 4G6/2.4L 18 ft/lbs (25 Nm) Plus 90°, +90°
1994-95 Galant 4G6/2.4L 18 ft/lbs (25 Nm) Plus 90°, +90°

The AERA Technical Committee

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