| Subject: | L59, LR4, LM4, LM7, LQ4, LQ9, LS1, LS6 New Exhaust Manifold Bolts and Torque Specifications for GEN III Vortec™ Engine |
| Models: | 1999-2003 Cadillac Escalade |
| 1999 Chevrolet Forward Control Chassis, P32 R/V Van Chassis, P42 Commercial Chassis |
| 1998-2002 Chevrolet Camaro |
| 1999-2003 Chevrolet Corvette, Express, Silverado, Suburban, Tahoe, W-Series Medium Duty Truck |
| 1999 GMC Forward Control Chassis, P32 R/V Van Chassis, P42 Commercial Chassis |
| 1999-2003 GMC Savana, Siera, Yukon, W-Series Medium Duty Truck |
| 1998-2002 Pontiac Firebird Formula, Firebird Trans Am |
| 1999-2003 Isuzu N-Series Medium Duty Truck |
| with GEN III Vortec™ Engine (VINs V, G, P, S, T, N, U, Z, -- RPOs 4.8L, 5.3L, 5.7L, 6.0L) |
A new exhaust manifold bolt and torque specification was introduced to the GEN III Vortec™ small block V8 engines beginning with the 2004 model year. When servicing any GEN III Vortec™ small bock exhaust manifolds, the exhaust manifold bolts
should be replaced.
-- P/N 11518860 Exhaust Manifold Bolts
Apply a 5 mm (0.2 in) wide bead of high temperature threadlocker to the threads of the exhaust manifold bolts before installing.
| • | P/N 12345493 - GM High Temperature High Strength Threadlocker (U.S.) |
| • | P/N 10953488 - GM High Temperature High Strength Threadlocker (Canada) |
Important: When tightening the exhaust manifold bolts it should be done with two passes. First tighten the two center bolts on the exhaust manifold. Then tighten the rest of the bolts, alternating from side to
side, while working towards the outside bolts.
Install the exhaust manifold bolts. Refer to the following torque sequence:
Tighten
| • | Tighten to 10 N·m(89 lb in) on the first pass. |
| • | Tighten to 20 N·m(15 lb ft) on the final pass. |
