Crankshaft Bearing Caution On
      1994-98 Toyota 3.0L 1MZ-FE Engines

The AERA Technical Committee offers the following crankshaft bearing caution for 1994-98 Toyota 3.0L 1MZ-FE engines. Currently, grinding the crankshaft as a repair option may not be a wise consideration. It appears that undersize bearing availability is limited and does not accommodate for grinding operations.

The manufacturer of this engine is currently supplying only standard thickness bearings. They break that down into a selective fitting of four different rod bearings and 5 different main bearings. Refer to the chart below for actual bearing crown thickness. So, currently, it would appear polishing or replacing this crankshaft are the only options available for repair.

Size    Rod Bearing     Main Bearing

1     .0584-.0585    .0979-.0980
2     .0585-.0587    .0980-.0981
3     .0587-.0588    .0981-.0982
4     .0588-.0589    .0982-.0983
5        N/A               .0983-.0985

Desirable oil clearance for connecting rod bearings is .0015-.0025 and .0010-.0018 for the main bearings.

AERA has spoken to several aftermarket bearing manufacturers and planned production dates for undersize bearings have not been determined as of the date of this publication. One aftermarket bearing supplier has indicated those bearings should be available during the first quarter of 1999.

                                                                     The AERA Technical Committee

                                          Interference Engines

The AERA Technical Committee would like to offer the following information on engines that present the possibility of interference between pistons and valves. The interference or contact may bend valve(s) when the timing between the camshaft and crankshaft is interrupted. This is generally the result of a timing belt or chain breaking or slipping.

The following list are engines that AERA is currently aware of that have exhibited interference. There may be other engines that are not listed below that have the possibility of piston to valve contact. If the engine you are working on is not listed, do not assume that it is a freewheeling design. It is suggested to add to this listing as additional information is obtained.

ACURA
1986-89 1.6L Integra
1991-95 1.7L Integra
1990-95 1.8L Integra 
1986-89 2.5L Legend
1992-94 2.5L Vigor
1986-89 2.7L Legend
1990      2.7L Legend
1991-95 3.0L NSX
1991-95 3.2L Legend

AUDI
1970-93 All Except 1970-77 
1.9L & 1970-73 1.8L

BMW
1987-95 2.5L 325I 525I
1994-95 4.0L 740I

CHRYSLER
1993-95 1.5L Colt 
1987-88 1.5L Colt	
1992-95 1.5L Eagle Summit
1987-88 1.6L Colt	
1989-92 1.6L Eagle Summit
1994-98 2.0L Neon Stratus
1990-95 2.0L Eagle Talon

DAIHATSU
1988-92 1.0L Charade
1988-92 1.3L Charade
1990-92 1.6L Rocky

FIAT
1974-79 1.3L 128 Series
1979-82 1.5L Stranda
1974-78 1.6L 124 Series
1974-78 1.8L 124 Series
1974-78 1.8L 131 Series, Brava
1979-82 2.0L Brava, Spider 

FORD
1981-85 1.6L Escort, EXP
1981-83 1.6L LN7, Lynx
1984-85 2.0L Escort, Tempo
1993-95 2.0L Probe
1986-88 2.0L Ranger
1984-87 2.0L Lynx, Topaz Diesel
1985    2.2L Ranger
1989-92 2.2L Probe
1986-88 2.3L Ranger
1986-87 2.3L Diesel Ranger
1991-98 4.6L Crown Victoria

GM
1986-95 1.0L Geo Metro
1989-91 1.0L Firefly (CANADA)
1985-88 1.5L Sunburst (CANADA)
1985-89 1.5L Spectrum
1990-93 1.6L Prizm, Storm
1981-84 1.8L Diesel (CANADA)
1982-86 1.8L Buick Skyhawk
1990-98 1.9L Saturn
1987-88 2.0L Buick Skyhawk
1988-95 2.3L Quad Four
1985-87 3.0L Buick
1979-95 3.8L Buick

HONDA
1986-87 1.0L Prelude
1973-78 1.2L All
1973-78 1.3L All
1980-84 1.3L All
1973-78 1.5L All
1985-89 1.5L Civic
1988-95 1.5L Civic, CRX
1993-95 1.5L Civic Del Sol
1979-84 1.5L All
1985-87 1.5L CRX
1993-95 1.6L Civic Del Sol
1973-78 1.6L All
1980-82 1.6L All
1988-95 1.6L Civic, CRX
1984-87 1.8L Prelude, Accord
1979-83 1.8L All
1986-91 2.0L Prelude
1990-91 2.1L Prelude
1990-95 2.2L Prelude, Accord
1992-95 2.2L Prelude
1995      2.7L Accord

HYUNDAI
1984-95 1.5L Excel Scoupe
1995-98 1.5L Accent
1992-95 1.6L Elantra
1993-95 1.8L Elantra
1992-95 2.0L Sonata
1989-91 2.4L Sonata
1990-95 3.0L Sonata

INFINITI
1990-92 3.0L M30

ISUZU
1987-89 1.5L I-Mark
1990-93 1.6L Stylus Impulse
1987-89 2.0L Impulse
1981-87 2.2L Diesel Truck
1986-95 2.3L Truck Trooper
1988-95 2.6L Truck Rodeo Amigo
1991-96 3.2L Trooper Rodeo Amigo

KIA
1995      2.0L Sportage

MAZDA
1984-85 2.0L 626 
1988-92 2.2L 626 MX6
1989-93 2.2L Pickup
1988-95 3.0L 929 MPV

MITSUBISHI
1985-95 1.5L Mirage Precise
1990-92 1.6L Mirage
1989-95 2.0L Galant Eclipse
1983-86 2.3L Diesel Pickup
1994-95 2.4L Galant

NISSAN
1982      1.5L Centra
1983-88 1.6L Sentra Pulsar
1987-89 1.8L Pulsar
1982-89 2.0L Stanza 300ZX
1984-95 3.0L Maxima 300ZX Pathfinder

PORSCHE
1976-83 2.0L 924
1976-89 2.5L 944 Series
1989      2.7L 944 Series
1989-91 3.0L 944 Series
1976-83 4.5L 928
1984      4.7L 928
1985-91 5.0L 928
1992-95 5.4L 928

SUZUKI
1985-94 1.3L Samurai Sidekick
1989-94 1.3L Swift

TOYOTA
1986-95 1.5L Tercel
1981-83 2.2L Pickup
1984-87 2.4L Pickup
1982-88 2.8L Celica Cressida
1987-94 3.0L 4-Runner

VOLKSWAGEN
1976-91 All Except 1.9 2.1L Engine
1990-92 1.6L Golf (CANADA) Jetta
1990-95 2.0L GTI Jetta GLI Passat

VOLVO
1991      2.3L Coupe 940
1986-94 2.3L 240 740 940 

                                                                              The AERA Technical Committee

                                          Premature Piston Damage On
                                          GM 2.5L (151 CID) TBI Engines

AERA members should consider the following when a GM 2.5L (151CID) TBI (Throttle Body Injection) has been diagnosed with premature piston failure.

Most often the pistons are damaged near the crown (top) whenever the engine has been subject to improper combustion.  Improper combustion can be the result of an incorrect air/fuel ratio, improper ignition timing, a malfunctioning computer or EGR (Exhaust Gas Recirculation) system.  Even if the EGR valve itself is operating, a blocked passage in the cylinder head or intake manifold can still lead to piston failures.  When the piston hasnot yet failed, an early sign of damage is a blue discolorationof the wrist pin.

It is important to clean all passages in the intake manifold whenever the cylinder head of an engine is remanufactured.  If the manifold is not removed with the cylinder head, AERA recommends that the installing mechanic verify that passages are free of debris.  Several machine shops have reported repeated
piston failures because the EGR passage was plugged.

For additional information see AERA Bulletins: TB 400, 374

                                                                    The AERA Technical Committee

                                       Coolant In The Oil On
                                  Toyota 20R & 22R Engines

AERA members have reported instances of engine coolant mixing with the engine lubricating oil supply.

In some of these cases, pressure testing the cylinder block and head has not identified the source of the leak.  However, close inspection of the aluminum front cover revealed an area where the timing chain wore through into a water passage.  

In this engine the water pump is mounted to the front cover.  When the timing chain stretches and the automatic tensioner is no longer able to take up the slack, the loose chain can slap against the front cover.  Continuous contact will eventually wear a hole into the front cover, introducing engine coolant into the
crankcase.

                                                                      The AERA Technical Committee

                                Piston Selection Caution On
                               Cummins 855 Series Engines

Particular caution should be exercised when selecting replacement pistons for Cummins 855 series engines.  Piston selection should be made in accordance with the CPL (Controlled Parts List) number associated with the engine.  

Early production engines as well as engines rated for low output do not use oil nozzles to cool the pistons.  The piston used in these applications features a barrel skirt profile.  Later engines as well as engines with up-rated horsepower output use oil nozzles in the cylinder block to aid in cooling of the pistons.  These applications use a sled runner skirt profile piston.

The critical difference between these two piston designs is that the sled runner piston is larger than the barrel design piston.  This results in approximately .0035-.0050 less piston to cylinder liner oil clearance.  Always consult the piston
manufacturer for the recommended clearances when remanufacturing these engines.

In some cases aftermarket parts catalogs are superseding the early style piston with the later design.  This should only be done when the engine is equipped with piston cooling nozzles.  AERA members have reported that using the sled runner design piston in engines not equipped with piston cooling nozzles and
operated in high demand applications can lead to random piston seizure.

A further consideration for the machinist when updating an engine from barrel design to sled runner design piston is adequate piston crown to cylinder head clearance.  While compression ratios remain the same, the compression distance of all sled runner pistons is 4.030 measured from the piston pin hole center line to the crown.  For comparison the barrel design pistons have various different compression heights depending on application, but all of them are shorter than the sled runner design, resulting in additional running clearance.

With a straight edge placed across the top of the cylinder liner, there should be a minimum clearance of .040 between the crown of the piston and the bottom of the straight edge when the piston is at top dead center (TDC).

If the clearance is from .030-.040 a .010 thicker head gasket can be installed, such as Cummins Part #3040180 or aftermarket equivalent.  If the clearance is less than .030, replacement of the cylinder block should be considered.  Machining of the piston is not recommended since it will alter compression ratios and combustion characteristics.

                                                                             The AERA Technical Committee