Oil Consumption On 
                                        1998 GM 2.2L VIN 4 Engines

The AERA Technical Committee offers the following information for oil consumption on 1998 GM 2.2L VIN 4 engines. Customers may complain of an abnormal amount of oil being consumed and need to add oil between oil changes. 

Engines manufactured before October 27, 1997 may not have sufficient enough baffling in the rocker arm cover to control oil flow into the foul air side of the crankcase ventilation system.  In addition, at high rpm operation of the engine, oil may be forced into the air cleaner duct.

The revised rocker cover, Part #24577253, has the sufficient amount of baffling to cure this problem. GM offers the following information on checking for oil 
consumption.

If the owner of the vehicle expresses a concern with oil consumption, an oil consumption test needs to be performed. Perform an oil change and make note of the mileage of the vehicle. Drive the vehicle for a sufficient number of miles 
for the engine to consume one quart of oil. At the end of the test review the amount of oil consumption. Consumption of more than 1 quart of oil in more than 2000 miles needs to be addressed. 

Some vehicles may already have the revised rocker arm cover installed. To verify if they do or do not, look for the identification mark on the valve cover shown in Figure 1. below. The mark is located toward the intake manifold side 
of the engine. If the vehicle already has the revised rocker arm cover installed, consider the following as a problem with oil consumption.

   External Leaks.
   Incorrect oil level or improper reading of oil level indicator.
   Improper oil viscosity.
   Continuous high speed driving and/or severe usage such 
   as towing, or driving in mountainous terrain.
   Blocked cylinder head, cylinder head gasket, or engine block oil drain holes.
   Valve guides and/or valve stem oil seals worn, or the seal omitted.
   Piston rings broken, improperly installed, missing,  worn, or not seated    properly.
   Pistons improperly installed or improperly fitted.

                                                                         The AERA Technical Committee

                                         Detroit Diesel Allison 71 Series
                                Cylinder Liner Compression Ring Gaskets

GMC has changed their specifications for the 71 series diesel engine cylinder liner compression ring gaskets.  Their tolerance specifications are such that when replacing these gaskets they must be replaced in matched sets.

The compression ring gaskets are color-coded on the top surface with a 3/4 black, white or orange stripe.  Each color represents the following compressed thicknesses:

                    Black stripe        .059 - .063
                    Orange stripe     .058 - .062
                    White stripe        .057 - .061

Mixing the colors of rings under any one cylinder may cause engine damage.

                                                                             The AERA Technical Committee

                                   Cylinder Head Resurfacing Caution On
                                  GM (GMC) 5.7L (350 CID) Diesel Engines

General Motor Corporation warned that it is not to possible to resurface the cylinder head on the 5.7L (350 CID) diesel engine due to the extremely tight clearance between the valves and the head of the piston. The prechamber must be recessed into the cylinder head by more than .005 or must not protrude out of the head by more than .003.

Note: GMC states that a cylinder head must be replaced if it is warped more than .010.

Before the cylinder head is reinstalled, make sure that the mounting bolt holes are tapped deep enough in the block and threads are not damaged. Blow out any chips or liquid and lightly oil the bolt threads in the block. Screw the bolt into the block by hand to a depth that is less than the cylinder head thickness.

Bolts that are rusty should be cleaned by wire brushing the threads. Before installing, lubricate the threads and underneath the head of the engine bolt with engine oil. Torque to 130 ft.lbs. (176Nm) in the sequence shown below:

                                                                                 The AERA Technical Committee

                                      New Cylinder Liner O-Ring Seals On
                                      Cummins NH/NT 6 Cylinder Engines

Cummins Engine Company has released new O-ring seals for the cylinder liners in NH/NT 6 cylinder engines.  The new seals are made of an EP material and have a smaller diameter cross-section.

The new seal replaces both the old center seal #3008998 and the old lower seal #183049.  The new seal carries Cummins part #3032874 and is black in color with one blue dot.

The new O-ring seals are not to be intermixed with the former seals on the same liner.  Cylinder liner deformation will result.  You can use the former seals and new seals in the same engine as long as they are used in the correct combinations on each liner.  The illustration below shows the correct combinations.

                                                                       The AERA Technical Committee

                                               Oil in Cooling System on
                                         VW 1.5L & 1.6L Diesel Engines

AERA members have reported instances of engine oil in the cooling system on VW 1.5L diesel engines.  According to AERA sources, the problem is related to a crack in the cylinder head bolt hole located near the oil gallery feeding the cylinder head.

The oil feed gallery in the block is located on one side of the center head bolt hole and a coolant jacket is on the opposite side of the bolt hole.  Pressurized engine oil is diverted through a slot in the head gasket and is feed up the side of the head bolt to the cylinder head.  The oil also follows the bolt back down to the bottom of the bolt hole.  Should the crack in the head bolt hole extend to the coolant jacket, oil can mix with engine coolant.

This problem is generally found on engines equipped with 11mm head bolt holes.  Later design engines utilize 12mm head bolts and do not exhibit this defect.  At the time of this writing no successful repair procedure is available.

                                                                       The AERA Technical Committee

                                        Cylinder Head Specifications on
                                              Case 207 Diesel Engines

The following cylinder head specifications should be considered when remanufacturing Case Model 207 diesel engine cylinder heads.

The minimum cylinder head thickness has been established at 3.968 with a new head measuring 4.000 +/- .005.  Heads are measured from the deck surface to the rocker cover rail.

Valve recession should be checked and adjusted if necessary to a maximum recession of .015, below the deck surface, for both intake and exhaust valves.  Valves on new cylinder heads are generally flush with a +/- .005 tolerance.

                                                                       The AERA Technical Committee

                                         Main Bearing Saddle Repair Kits

The Cummins Engine Company has made main bearing saddle repair kits available for several engines.  These kits can be used to salvage cylinder blocks when a main bearing has spun and the main bearing saddle has been damaged.

Each kit contains an 1/8 drill bit, two hold down bolts (one for the lock ring and one for the other side of the saddle), a quantity of rivets and the appropriate number of repair sleeves.  Semi-finished or good used main bearing caps are also needed to complete the repair.

A main bearing saddle can be successfully repaired by following this procedure.
                                                                                                                            Remove the main bearing cap from the saddle to be repaired.  Using the appropriate align bore tooling remove .050 of material out of the saddle.  This will enlarge the main bearing bore by .100.

Clean the saddle and lock tang area.  Install the repair sleeve and align the lock tang slot of the sleeve with the one in the block.

From the repair kit, install the washer marked L on the lock tang side of the saddle.  Install the second washer on the opposite side.  Install the hold down screws and torque to 20 lbs.ft. (Figure 1).

Mount the 1/8 drill bit in a right angle drill, so that the drill extends 1/4 beyond the chuck jaws.

Using the 4 holes in the repair sleeve as a guide, drill through each of the holes into the saddle.  The proper hole depth is achieved when the chuck jaws contact the repair sleeve.

Clean the 4 holes and install the supplied rivets (Figure 2).  Peen the rivets until they are flush with the repair sleeve.

Remove the temporary hold down bolts and trim the ends of the repair sleeve so they are flush with the main bearing saddle.

Clean the main bearing bolt holes and install a good used or semi-finished main bearing cap.  Torque the main bearing bolts to specifications.

Using the appropriate align boring tools, refinish the main bearing housing bore to specifications.  Approximately .050 of material should be removed from the repair sleeve.
                                                                             
Main bearing bore repair kits or sleeves may also be available from several aftermarket sources.

                                                                        The AERA Technical Committee