| CAUTION ON OVERTORQUING SPARK PLUGS ON L6 ENGINES |
Caution On Over-Torquing Spark Plugs On
Oldsmobile L-6 Engines
The General Motors Oldsmobile Division issued a bulletin warning against over-torquing spark plugs on L-6 engines which use tapered seat spark plugs.
Over-torquing will cause stretching of the plug shell which could permit blow-by to pass through the gasket seal between the shell and the insulator. Problems also result when the spark plugs have to be removed.
The torque specification for the L-6 engine is 15 ft. lbs.
The AERA Technical Committee |
| PILOT BEARING INSTALLATION |
Pilot Bearing Installation For Crankshafts On
1970 GM (Oldsmobile) 5.7 & 7.5L (350 & 455 CID) Engines
Oldsmobile division of General Motors Corp. specifies that when a service crankshaft is installed in a 1970 5.7 & 7.5L (350 & 455 CID) engine equipped with a manual transmission, the pilot bearing should not be staked in place.
A snap ring, Part No. 9425556, should be used to retain the pilot bearing in the crankshaft as illustrated below:
The AERA Technical Committee |
| POWDERED METAL CAMSHAFT SPROCKET INTRODUCTION |
Powdered Metal Camshaft Sprocket Introduction On
General Motors 2.3L Quad 4 Engines
General Motors has introduced a new camshaft sprocket in the later production 1992 2.3L Quad 4 Oldsmobile engine. The new sprocket is now made of a powdered metal material and previous sprockets were made of a ferrous type metal.
This composition change is one that is becoming prevalent in many engine components today, in both light and heavy duty divisions. Powdered metal components are considerably lighter and less expensive to manufacture. They are used primarily in components that are subjected to no torsional stress. Their wear properties when used in these unique situations are comparable to those of their predecessors, the heavier ferrous metals. They also have the distinct advantage of superior operation (in a compatible environment) over the once-used composite materials with non-ferrous metal timing components.
General Motors indicates that the updated gear is being used in vehicle applications distinct to the L cars and specifically to VIN Code A. This newly designed gear is the replacement for any earlier production vehicles in this classification and carries the GM Part #24570973. Along with the newly designed gear, the introduction of a new wrench, GM Part #J 39579 tool (replaces GM Part #J 36013), which is required for successful installation.
Both wrenches are used in the identical manner, as the appropriate procedure in the service manuals indicate (seeillustration).
AERA is aware of one aftermarket manufacturer supplying the tooling required to successfully change the old and new camshaft sprocket gears.
The AERA Technical Committee |
| PISTON TO ROD ORIENTATION ON OLDS V8 |
Piston To Rod Orientation On
Oldsmobile V-8 Engines
AERA members have reported confusion over piston to rod orientation on Oldsmobile V-8 engines. The confusion centers around the fact that not all Oldsmobile V-8 connecting rods have squirt holes at the parting lines. It has also been reported that engines using the later type connecting rod without the squirt hole have random piston to rod orientation.
When using connecting rods with a squirt hole, assemble the piston to the rod with the squirt hole facing the center (inboard) of the engine.
When using connecting rods without squirt holes, there is no specified piston to rod orientation. Because these rods have neither a squirt hole or front and rear side, they can be assembled to the pistons at random. For purposes of uniformity, it is recommended that a specific procedure be adopted for assembling this type of rod to the pistons. A good choice would be with bearing
tangs to the outside of the engine, which is common with other GM engines.
The AERA Technical Committee |
| REVISED REAR MAIN OIL SEAL INSTALLATION PROCEDURE |
Revised Rear Main Seal Installation Procedure On
1982-83 GM 4.3L & 5.7L Diesel Engines
AERA members should note the General Motors has revised its rear
main seal installation procedure for the engines mentioned above.
The procedure is as follows:
1. Clean the seal groove in the block and/or cap as necessary.
2. Apply a thin even coat (about two drops of bonding
adhesive)of GM part #1052621, Loctite 414, Fel-pro 361 (Mighty
Seal), or equivalent over the entire seal surface of the groove.
3. WITHIN ONE (1) MINUTE, install the seal. After one minute,
the adhesive begins to cure and loses its bonding ability.
Most adhesive have a shelf life of about one year, but should be
considered usable if it flows freely from the container.
The above procedure should also be used on all previous
Oldsmobile manufactured diesel engines which utilize a rope-type
rear main seal.
The AERA Technical Committee
October 1983 - SPB 106
##END## |
| KEY WAY SPROCKETS |
1/2 Keyway Crank Sprockets On
GM (Oldsmobile)
There has been a great degree of confusion with engine rebuilders regarding GM (Oldsmobile) crank sprockets with the keyway only going half-way through the sprocket. This condition is referred to as a blind keyway and is the design of the sprocket by GM (Oldsmobile) engineers.
The S349 sprocket utilized the full length keyway during the model years 1964-68. The blind keyway was introduced by GM (Oldsmobile) in 1969 and was still present in its 1973 models.
The S361 sprocket utilized the full length keyway during the model years 1965-1968. The blind keyway was also introduced by GM (Oldsmobile) in 1969 and it, too, was still present in its 1973 models.
We are often asked by rebuilders as to why GM made this change as the appearance of the blind keyway resembles an incomplete operation. To the best of our knowledge, the purpose was to eliminate cracking or stresses applied to the sprocket during installation by rebuilders as they were encountering a number of broken crank sprockets that didn't become apparent until the engine was in operation. It is recommended that the blind keyway be used in all model years (1964-73) to prevent such occurrences.
The AERA Technical Committee |
| VALVE TRAIN TICKING NOISE AND/OR BACKFIRING |
Valve Train Ticking Noise And/Or Backfiring On
1980-83 Oldsmobile 5.7L V-8 Diesel Engines (Vin Code N)
Some of the subject engines may experience a valve train ticking
noise and/or a backfiring condition. The cause may be premature
rocker arm pivot wear.
The original rocker arm pivots were purchased from two vendors.
Identification for each can be found on the underside of the
rocker arm pivot bridge as shown in Figs. 1 and 2 below.
The pivot assemblies that are showing premature wear are those in
Fig. 2.
CAUTION: It is recommended that only the pivots illustrated in
Fig. 1 should be used.
(insert Figures 1 & 2)
The AERA Technical Committee
August 1983 - TB 287
##END## |
| NEW CYLINDER HEAD BOLT |
Cylinder Head Bolt Replacement On
GM 5.7L (350 CID) Oldsmobile Diesel Engines
The old style diesel cylinder head bolts on the subject engines
may stretch without breaking resulting in insufficient torque at
that bolt. A new bolt, identified by a dash (-) on the bolt head
is of sufficient hardness that stretching will not occur. the
new style bolt does not require replacement when a cylinder head
is removed for service unless it is broken.
The AERA Technical Committee
April 1983 - TB 271
##END## |
| NEW CYLINDER HEAD BOLTS |
Cylinder Head Bolt Identification On
General Motors (Oldsmobile) Diesel Engines
During 1980, new higher strength cylinder head bolts were used in
production of General Motors (Oldsmobile) diesel engines. The
new cylinder head bolts can be identified by either a bar stamped
on the bolt head or yellow paint. Some bolts may have both bar
and yellow markings.
Whenever these head bolts have to be replaced on any General
Motors (Oldsmobile) diesel engine, the new head bolts are
recommended.
The bolts should be lubricated with light oil and torqued to 130
ft/lbs.
(insert illustration)
The AERA Technical Committee
January 1982 - TB 244
##END## |
| OVERSIZE VALVE LIFTERS AND GUIDES |
Oversize Valve Lifters & Guides On
Some GM (Olds) 5.7L (350 CID) Diesel Engines
Some GM (Oldsmobile) built 5.7L (350 CID) diesel engines may be equipped with one or more oversize lifters and oversize valve guides.
If there is an 0 cast into the side of the lifter boss as shown in the diagram below, that lifter is oversize. Oversize lifters are .010 larger than standard diameter lifters.
To determine an oversize valve guide, check for the number stamped into the cylinder head just above the intake gasket surface. The valve next to the stamped number is oversize. The number indicates the size of the guide. For example, a 13 indicates a .013 oversize guide.
The AERA Technical Committee |
