Upper Intake Manifold (Composite) - New Features
Bulletin Number: 93-6-16Reference Number: 206005
Publish Date: 12/92
Subject:
NEW COMPOSITE UPPER INTAKE MANIFOLD (INFORMATION)
Models Affected:
1993 BONNEVILLE AND TRANS SPORT MODELS WITH 3800 V-6 (L27) ENGINES
The 1993 3800 TPI Engine used in Bonneville and Trans Sport models has a composite upper intake manifold. The purpose of this bulletin is to familiarize technicians with some unique features of this manifold.
1. The manifold is molded of a composite material. This makes it considerably lighter than past model upper manifolds.
2. The throttle body and fuel rail are retained to the upper manifold with "torque spin" studs and well-nuts. These studs and nuts are designed to torque spin (turn) in the manifold if subjected to torque loads over 22 N-m (16 lbs.ft.). This was done to prevent damage to the manifold if any studs or bolts are overtorqued.
NOTE:
It is not necessary to replace the manifold should a stud or well-nut spin in the manifold. Studs or well-nuts can be retained from the backside using a 15 mm wrench.
IMPORTANT:
WHEN REINSTALLING A THROTTLE BODY, IT IS IMPORTANT THAT THE RETAINING STUDS BE COATED WITH LOCTITE 242 OR EQUIVALENT TO PREVENT THE NUTS FROM VIBRATING LOOSE.
TORQUE SPECIFICATIONS:
THROTTLE BODY TO MANIFOLD STUDS 12-18 N-m
(9-13 lb.ft.)
FUEL RAIL TO MANIFOLD WELL-NUTS 10-14 N-m
(7-10 lb.ft.)
FUEL RAIL TO MANIFOLD (BLIND HOLE) 10-16 N-m
(7-12 lb.ft.)
3. The new "click and lock" connectors were designed for retaining the PCV valve, vacuum block and EGR pipe. This design, with a quick connect/disconnect feature, will aid in assembly/disassembly.
4. The seal between the upper and lower intake manifold is reusable when it has NOT been removed from its retaining channel. This seal has been designed to swell in the upper manifold gasket channel after installation to aid in sealing. IF THIS SEAL IS REMOVED FROM THE UPPER MANIFOLD GASKET CHANNEL, THE SEAL GASKET MUST BE REPLACED.