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The following technical bulletins were published by AERA.


                                               Cylinder Block Identification On  
                                                 BMW 4.0L DOHC M60 Engines

The AERA Technical Committee offers the following information cylinder block identification on BMW 4.0L DOHC M60 Engines. BMW used two different cylinder wall-finishing processes during production, which are called Nikasil and Alusil. Each block is fit with pistons and piston rings especially for the cylinder bore finish and never should be interchanged.

Nikasil is an aluminum alloy block with nickel dispersion-coated cylinder bores and was used on the M60 engines and replacement blocks. Nikasil version incorporates crosshatch hone marks in the bore finish. Alusil is an aluminum silicon alloy used in M60 replacements and M62, M70 and M73 engines. Alusil version has smooth gray cylinder bore finish without cross hatch marks.

A quick way to know what type of cylinder block you have is by the casting number. Block casting numbers are located on the right side of the block next to the coolant drain bolt. 

                    Casting Number                    Cylinder Block Version
                   1725970-1714212                     M60 B30 Nikasil
                   1745871                                    M60 B30 Alusil
                   1725963-1742998                     M60 B40 Nikasil
                   1745872                                    M60 B40 Alusil
                   1745873                                    M62 B44 Alusil

                                                                  The AERA Technical Committee


                     Flywheel Specifications

The following flywheel specifications may be used as reference
when surfacing flywheels.

                   Type of 
Manufacturer       flywh. Specs.          Comments

BMW                Step   .013 - .015
Datsun             Step   .003 - .005   No groove
                   Flat                   With groove
Datsun 240Z        Step   .010           With groove
Fiat Spider 1600   Step   .018
Ford Falcon        Cup    .018           6 Cylinder engines
Ford Courier       Cup    .285
                   Cup    .310
Ford Ranger        Cup    .003           V6 Cylinder engines
GM                 Cup    .125
GM - Buick         Cup    .125           V6 Cylinder engines
GM - Spirit        Cup    .195
Honda              Cup    .030           Small cup
                   Cup    .100 - .104   
                   Cup    .785           Long alignment pins
                   Cup    .900            Short alignment pins
Honda Accord       Cup    .615           
Mazda              Cup    .062           Rotary engines
Subaru             Cup    .785
Toyota             Step   .018 - .022   Large alignment pins
                   Cup    .055           Small cup
                   Cup    .965 - .970    Tercel, large cup
                   Step   .040           Tercel, step
                   Step   .020           Land Cruiser
VW                 Cup    .945           Air cooled, 6 Volt
                   Cup    .830           Scirocco
                   Cup    .835           Rabbit/Golf
                   Cup    .982           Air cooled bus engine
                   Cup    .830           Air cooled engine
                   Cup    .885           Air cooled engine

Specifications listed for Step type flywheels refer to the
height of the wear surface above the pressure plate mounting
surface.  Specifications for Cup type flywheels refer to the
height of the pressure plate mounting surface above the wear

                                     The AERA Technical Committee

February 1988 - SB 153



                                                       Oil Filter Caution For
                                     BMW Extended Oil Change Interval Engines

The AERA Technical Committee offers the following information regarding an oil filter caution for extended oil change interval engines. These engines, the M52TU, M54, M62 and M73 may be affected if the proper oil filter element is not used when extended oil filter intervals are endured. BMW has offered this extended 15,000-mile interval service to certain high performance vehicles only if the service is implemented by a BMW dealer. This extended interval period also mandates the use of specifically formulated synthetic engine oil obtained from BMW.

A new oil filter element has been developed for all BMW models with extended service intervals (approximately 15,000 miles). This filter must be used whenever an oil service is performed on an extended oil change interval engine. The new oil filter element incorporates improved filter paper, which prevents filter deterioration caused by high engine oil temperatures over extended time. The new oil filter element was phased into production on M54 powered vehicles in September of 2000 and on all M62 and M73 powered vehicles in July 2000. 

Using any other filter or engine oil in these engines may prove harmful to the engine if the filter paper deteriorates before filter replacement. At this time BMW approves no other filter or oils for use on these engines.

                                                                          The AERA Technical Committee


           Revised Cylinder Head Mounting Components and Procedures on
           BMW 1983-86 325e and 528e (VIN M20B25 and M20B27) Engines

AERA has received many calls on leaks of the cylinder head to block joint and cylinder head bolt breakage on BMW M20 series engines (applicable to all displacements).  The following revised components and procedures should eliminate these difficulties for AERA members and their customers.

A revised cylinder head gasket with improved sealing should eliminate oil seepage between cylinders No. 3 and 4 on the exhaust side of the engine.  A .012 (.3mm) thicker head gasket should be used when cylinder block deck height or cylinder head minimum thickness specifications are exceeded.  

     Previous Head Gasket          11 12 1 278 305
     Standard Head Gasket          11 12 1 708 891
     Oversize Head Gasket          11 12 1 713 493

Revised cylinder head bolts of increased strength and hardness along with a new torque procedure should further reduce head gasket problems.  The revised cylinder head bolts are easily identified by their Torx heads and black finish.  BMW recommends installation of the revised bolt whenever the cylinder
head is serviced.  Bolts should be replaced as a complete set available under the Part #11 12 1 726 478 (14 bolts).

Use the following torque procedure on the revised bolts:

     1)   Torque all bolts to 22 lbs.ft. (30 Nm)
     2)   Turn all bolts 90^
     3)   Turn all bolts an additional 90^

The waiting and running time requirements used with previous procedures no longer apply.
                                                                                                                                                                                                         The AERA Technical Committee


                                 Coolant In The Engine Oil Supply On
                                           1991-93 BMW 1.8L Engines

AERA members have reported coolant in the engine oil supply on 1991-93 BMW 1.8L engines. The cause of this condition may be the result of a deteriorated front cover gasket and/or the erosion of the timing cover mating surfaces. That leakage may allow engine coolant to pass around the gasket and enter the engines oil supply. This condition may also show evidence of external coolant leakage at the engine's front timing cover aera. 

In most instances, if the cover is leaking externally, it is also leaking internally. Ignoring a slight amount of external leakage, may lead to extensive engine damage if it is also leaking internally.

Vehicles built after approximately 10/1/93, have a revised optimized rubber material composition and reduce the possibility of this problem occurring. 

To repair a metal erosion condition, BMW authorizes the use of a metal epoxy type repair to the gasket mating surfaces of either the cylinder head or timing cover. Many AERA shops have been successfully welding those areas.

                                                                        The AERA Technical Committee


                    Oil Seepage from Cylinder Head                                                              On BMW 1991-93 1.8L Engines

The AERA Technical Committee offers the following information regarding oil seepage from cylinder head on BMW 1991-93 1.8L engines. This engine is referred to as M42 and is used in 318 I vehicles.

Oil seepage may occur from the left side of the cylinder head at the lower mounting bolt. The cause of the oil seepage is due to a casting shrinkage 
cavity. It is located between the M6 threaded hole for the timing chain tensioning rail mounting and the M8 threaded hole for the intake manifold support 
bracket, as shown in Figure 1.

To correct this problem on M42 engines produced since April 1993, the lower bolt for the intake manifold support bracket has been installed with 3 Bond 1209. 
It is also marked with a black paint spot.

This repair procedure applies if oil seepage is evident coming from the lower mounting bolt # 1 as shown below. To repair, remove the bolt and degrease 
the bolt threads (#2) and bolt hole threads. Then, apply liquid sealing compound 3 Bond 1209, BMW Part # 07 58 9 062 376 on the bolt, reinstall bolt and torque to 12-13 ft/lbs.

                                                                         The AERA Technical Committee


                Engine Coolant Leaks On 
                1988-90 BMW 5.0L Engines

AERA members have reported engine coolant leaks on 1988-90 BMW 
5.0L engines. The coolant seems to be coming from the coolant 
chamber cover on top of the engine block due to a distorted 
cork gasket. 

BMW now offers a new style gasket, Part # 11141736959, to 
reduce the possibility of this problem. The new gasket is made 
of a plastic-coated paper, which is colored green. Anytime a 
repair or a replacement of a part is done, this new gasket 
should be installed.

As of September 1989 production, the coolant chamber cover was 
modified to improve the gasket contact surface by widening the 
sealing lugs around the boltholes. When a new style cover is 
installed on a vehicle prior to September 1989 production, make 
sure that the wider bolt hole lugs on the cover do not contact 
the engine block. 

The old style cork gasket, Part #11141288979, is no longer 
available individually. The old style cork gasket is included 
in the engine block gasket set and must be replaced with the 
new rubber gasket. 

AERA is currently unaware of an aftermarket supplier for this 
revised gasket.

                                The AERA Technical Committee

January 1999 - TB 1648  



                                            Coolant Leak from Cylinder Head On
                                            1995-2000 BMW 2.8L M52 TU Engines
The AERA Technical Committee offers the following information regarding a coolant leak on 1995-2000 BMW 2.8L M52 TU engines. This leakage has been located at the front right side of the cylinder head corner directly below the BMW insignia cast into the head. 

Coolant Leak from Front Right Side of the Cylinder Head 
Z3 2.8L and 2.3 with M52 TU engines produced from 9/99 - 10/99.
E46 328 and 323 with M52 TU engines produced from 9/99 - 10/99E39 528 with M52TU engine produced from 9/99 - 10/99 

Apparently some cylinder heads were cast with a machining flaw (hair line crack) and may have been installed on M52 TU engines in production on a limited number of vehicles. The leakage has been observed to be in the area indicated by the black arrow in Figure 1 below. The machining flaw (if present) is located in the front right side of the cylinder head and will cause a coolant leak in the area of cylinder head to block joint.

Figure 1.

Parts required to repair this condition are listed in the table below.

Figure 2.

                                                                            The AERA Technical Committee

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