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The following technical bulletins were published by AERA.


                                     Milky Deposits In The Crankcase On
                                              1988-91 GM 2.3L Engines

The AERA Technical Committee has been informed of a condition of milky deposits in the crankcase of 1988-91 GM 2.3L Engines.  It is normal for moisture to accumulate in the engine's oil in cold weather which can cause milky deposits to form on internal engine surfaces visible on the oil dipstick.  If these conditions persist, the engine oil and filter should be changed every 3000 miles or three months, whichever comes first.

This condition is most common in internal combustion engines and is more visible in the quad four engine, due to its cooler running and operating efficiency.  VIN codes A & D, in the Oldsmobile Cutlass Calais have been directly affected. 

                                                                    The AERA Technical Committee


         Method To Restore Worn Cam Gear Thrust Area On
                       Some Engine Blocks

Many late model engines (Chevrolet small block and 6.5L (396
CID), Dodge & Plymouth 3.4L (225 CID), Oldsmobile 4.0 & 4.3L (425
& 455 CID), Buick 4.1L (401 CID) and others) do not have camshaft
thrust washers, but depend upon the mesh of the distributor drive
gear to retain the camshaft.  Often the cam gear or sprocket
causes the front of the block to wear to such an extent that
repair is needed to return the block to service.

A relatively easy yet effective repair is suggested:

     (1) Make a metal brush (similar to a cam bearing drive plug)
     approximately 2 long with the outside diameter to fit the
     cam bearing housing bore.  Provide a slight taper on the
     O.D. to prevent the bushing from going all the way through. 
     Drill an inner hole in the bushing to accept a valve seat
     installation pilot.  Modify a valve seat cutter shank to be
     turned by 1/2 electric drill and attach a cutter head
     proper diameter to match the O.D. of the worn circle.

     (2) Cut the front of the block the depth of a Y91
     Continental main bearing thrust washer.  The O.D. of the
     thrust washer should be machined to press fit in the
     machined counterbore.  The I.D. of the thrust washer should
     be machined to fit freely over the cam bushing.  The Y91
     thrust washer should then be installed.

After tooling up for this operation, the entire procedure should
take no more then five minutes and the only cost is that of the
thrust washer.

NOTE: Depending upon your valve seat equipment, it may be
necessary to change the above tooling to accommodate your

                                     The AERA Technical Committee

April 1973 - SPB 18



                                 Rubber Rear Main Seal Alternative On            
                                General Motors (Oldsmobile) V8 Engines 

A rubber alternative to the rope rear main seal found in all GM (Oldsmobile) V8 engines can be made from the rubber rear main seal designed for Chrysler (AMC) 3.2L-4.2L (199-258 CID) engines and the seal designed for the Ford Motor Company 7.0L-7.5L (429-460 CID) engines. 

McCord Gasket Corporation engineers report that the rubber seal for the Chrysler (AMC) 6 cylinder engine can be used in several GM Oldsmobile V8 engines by trimming off the tabs on the upper half of the AMC seal (see illustration below). 

When modified, both halves of the AMC seal will be equal and will properly fit in the seal cavity of the Oldsmobile blocks.  The AMC seal will fit Oldsmobile-built 4.3L, 5.0L and 5.7L (260, 307 and 350 CID) engines (gas only) once the seal has been modified. 

The Ford 7.0L-7.5L (429-460 CID) engine seal will fit the 6.6L (400, 425, 455 CID gas) and 5.7L (350N CID) (diesel) engines with no modifications necessary to the seal. 

AERA members should keep in mind that these modifications have not been authorized by GM (Oldsmobile).  Tests in the field have shown great success, however. 

                                     The AERA Technical Committee 

April 1986 - SB 128R 



                                   Premature Rod Bearing Failures On
                                  Some GM (Oldsmobile) 6.6, 7.0 & 7.5L 
                                          (400, 425 & 455 CID) Engines

Some premature rod bearing failures have been experienced especially in the 6.6, 7.0 & 7.5L (400, 425 & 455 CID) Oldsmobile engines.

In checking these engines it was found the side clearance on the rods was less than the minimum specifications.

The side clearance is necessary to allow enough oil to flow for proper heat dissipation. We suggest when rebuilding these engines, rod side clearance should be checked and increased when necessary to fall within manufacturer's specifications. 

                                                                                 The AERA Technical Committee


                    Cylinder Head Bolt Torque Caution For 
                1968-90 GM 5.0, 5.7L VIN Y, 8, B & R Engines 

The AERA Technical Committee offers the following information regarding a cylinder head bolt torque caution for 1968-90 GM 5.0L, 5.7L VIN Y, 8, B & R engines. These engines were manufactured by Oldsmobile.

Reports of conflicting torque values listed in different manuals has added to the problem of finding the correct torque value for these Oldsmobile engines. The simplest way to find out what torque to use is measure the diameter of the cylinder head bolts that the engine you are working on is using.

             5.0 & 5.7L 1980 through 1990 used ?" bolts, torque to 130 ft/lbs.

             5.7L 1977 through 1980 used ?" bolts, torque to 130 ft/lbs.

             5.7L 1968 through 1976 used 7/16" bolts, torque to 85 ft/lbs.

7/16 or .437 diameter bolts use 85 ft/ lbs. of torque and tighten in equence.
1/2 or .500 diameter bolts use 130 ft lbs. of torque and tighten in sequence excluding 1989-90 5.0L VIN Y engines.

Note: It is acceptable to drill the 7/16 bolt heads for use on a block using 1/2 bolts.  To do so, just drill all cylinder head bolt holes out using a 9/16 bit to allow clearance for the ? bolts.

Caution: 1989 & 1990 5.0L VIN Code Y engines require torque to yield head bolts (TTY) and use a torque turn method of tightening. Follow the steps listed below for those ? bolts

                1. First step Torque all bolts in sequence to 40 ft/lbs.
                2. Second step Rotate bolts # 1-7 and #9 an additional 120°.
                3. Third step Rotate bolts #8 and 10 an additional 95°.

                                                                              The AERA Technical Committee


                                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 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


                          Unusual Engine Performance On Late Model Cars
                                  Caused By Defective Exhaust Systems

This bulletin is a reminder that defective exhaust systems cause unusual engine performance.  A few recent case histories will emphasize the need to be alert for this problem:

(1) A Ford 6 cylinder OHV engine would not idle properly after the installation of a rebuilt engine.  After many hours of testing, another short block was installed with the same results. Finally, the exhaust pipe was disconnected and the trouble

(2) A Buick V-8 would run well up to 45 mph then flatten out. After checking every tune up possibility with no results, the exhaust system was checked and the trouble found.

(3) A Cadillac made a screeching sound at 2200 rpm.  A new converter and transmission overhaul failed to change matters.  A new exhaust system cured the trouble.

(4) A Mustang 4.7L (289 CID) would run well at road speeds for 2 or 3 miles, then lose power.  A scope indicated perfect tune, but the trouble continued until a new exhaust pipe was installed.

(5) A Lincoln had peculiar noise that would not go away until the exhaust pipe was changed.  The inner pipe had burned through, allowing a piece of tubing to flutter like a faulty heat riser valve.

(6) An Oldsmobile ran like the camshaft was worn, but upon removal, it was found to be good.  The exhaust system was changed to eliminate the problem, and, after cutting the old pipe, the cause was obvious.  The inner pipe had closed down to provide an opening the size of a nickel.

(7) A 1966 Chevrolet 5.4L (327 CID) ran well at town speeds and checked out perfectly on a scope.  At 2600 rpm, however, a total loss of power occurred.  The cause was a collapsed inner pipe.

Case histories prove the need for service men to be cognizant of the problems caused by double wall exhaust pipes.  The high heat generated inside the inner tube creates a metal fatigue that may result in deformities.  Internal muffler deterioration and carbon build-up can also cause poor engine performance.

Inner pipe problems usually can be detected by puttiong the car on a hoist.  With the engine running fast, listen along the length of the exhaust pipe.  An obvious noise can be detected if the inner pipe is bad.  The location to check first in pipes hooked to a V-8 with a single exhaust is just behind the Y of
the two pipes.
                                                                          The AERA Technical Committee


                     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
                                       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

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