Camshaft Friction Gear Noise On 
                                      1992-97 Mazda 1.8 & 2.5L Engines

The AERA Technical Committee has obtained the following information on a camshaft friction gear noise on Mazda 1992-97 1.8 & 2.5L engines. The noise is most audible at the right rear cylinder head, exhaust camshaft area and is described as a metalic tapping noise. During  normal engine operating 
temperatures and approximately 1200 rpm, the noise is the loudest. 

The cause of this noise is a reduction in the torque between the camshaft friction gear and the camshaft drive gear. This can occur during normal vehicle driving and use.

To cure this type of condition, Mazda offers a revised friction gear spring and a new locking nut. The friction gear spring can be ordered under Part #KL01-12-417B and the locking nut can be obtained with Part #KL01-12-417A.

	Parts Description	Part #
	
	Friction Gear Spring	KL01-12-417B
	Locking Nut		KL01-12-417A

Some AERA shops report replacing these parts anytime the 
camshaft gear is removed to prevent a future noise complaint.

                                                                          The AERA Technical Committee

                  Timing Chain Installation On
                   1979-85 Mazda 2.0L Engines


Correct installation of the timing chain on 1979-85 Mazda 2.0L
engines is critical to achieve the proper valve timing.

Rather than aligning the camshaft and crankshaft gears with marks
on the cylinder head or block, this engine uses marked plates on
the timing chain to set valve timing.  
Start the timing process by rotating the crankshaft and camshaft
sprockets until the keyways are facing straight up (12 o'clock). 
This should face the camshaft sprocket timing mark at 3 o'clock
and the crankshaft sprocket timing mark at approximately 5
o'clock looking at the front of the engine.

Locate the three marked links on the timing chain.  Two links
should be positioned at the crankshaft sprocket so that the
timing mark is between the links (Figure 1).  Position the chain
and camshaft sprocket so that the mark is in the middle of the
other marked link (Figure 2).  There should be 20 unmarked plates
between the two positions.

Be careful, some timing chains do not use marked plates to
indicate the correct timing positions for the camshaft and
crankshaft.  Use the old chain as a guide to make your own marks
on the new chain. 
 
                                     The AERA Technical Committee


August 1991 - TB 796

##END##

                                                  Valve Train Noise On
                                             1993-94 Mazda 2.0L Engines

The AERA Technical Committee offers the following information regarding a valve train noise on 1993-94 Mazda 2.0L engines. This noise can be associated with the Hydraulic Lash Adjusters (HLA).

This noise appears after the engine has been run at idle for a long period of time. The noise appears because air is entering the oil gallery. To prevent this condition from happening, Mazda had redesigned the oil pump plunger as shown in Figure 1.  

HLA noise will appear at the top of the engine and is several times faster than that of the engine speed. Verify the complaint by running the engine at idle for a period of time not letting the vehicle overheat. If the HLA noise is present, replacement of the oil pump plunger is required. 

To replace the oil pump plunger, remove the snap ring at the bottom of the pump as shown in Figure 1. Remove spring seat, pressure spring and the plunger. Replace the old plunger with the new plunger, Part #JF01 14 115. Reassemble the bottom of the oil pump in the reverse procedure of disassembly

NOTE: Follow instructions in the service manual for disassembly and assembly of the engine to get access to the oil pump for replacement of the plunger.

                                                                        The AERA Technical Committee

                                          Coolant In The Oil On
                                     Mazda 1.5 & 1.6L Engines

AERA member machine shops should carefully inspect the cylinder head when resolving engine oil contamination complaints.

The cylinder head carries two cup type freeze plugs on the valve spring side of the cylinder head.  Leaking freeze plugs will accumulate a black residue during operations.  Pressure testing the cylinder head confirms that the plug or plugs were leaking.  

Successful repairs include replacement of the plug or peening the metal surrounding the plug over it.  Be sure to re-pressure test the cylinder head after repairs are completed.

                                                                              The AERA Technical Committee

                                 Camshaft & Lifter Break-In Procedure For
                                            Mack E-Tech Diesel Engines 

The AERA Technical Committee offers the following information regarding the recommended camshaft and lifter break-in procedure for Mack E-Tech diesel engines. This procedure should be performed anytime a lifter or camshaft replacement is done. 

When performing a camshaft and lifter replacement or a major engine overhaul, it has been determined that careful pre-lubrication and break-in are necessary for cam and lifter longevity. The following procedure is especially important when new parts are used. 

1. Submerge the valve lifters and the unit pump lifters into a container of clean engine oil. Submerging the lifters allows oil to fill the passage to the lifter roller axle. After the lifters have been submerged in the oil, take the lifters, hold them vertically and spin the roller to ensure that oil flows to the surfaces between the axle and roller. Caution: Performing this lifter pre-lube is critical to provide adequate lubrication to the axle and roller at initial engine start-up, especially when new components are used.
2. Apply clean engine oil to the camshaft lobes and bearing journals. Make sure oil is applied 360 degrees around the lobes and journals. Lubriplate-type break-in grease may be substituted for clean engine oil if so desired.
3. Pre-fill two new spin-on oil filters with two quarts of recommended engine oil and then install the new oil filters.
4. Pressure lube the engine by disconnecting the turbocharger oil supply line at the turbocharger and connecting a suitable engine pre-lubricator tank such as a Kent Moore #J39258 or equivalent. Fill the pre-lubricator tank with the recommended engine oil, and apply 5 psi air pressure to the tank for a minimum of five minutes. After the engine has been pressure lubricated, fill the oil pan with the balance of oil. Pressure pre-lube provides optimum lubrication for the cam and lifters at initial engine start-up.
5. Start the engine and immediately increase engine speed to 1200 rpm. Set the electronic hand throttle to 1200-1600 rpm and run the engine at that speed for fifteen minutes. NOTE: Do not allow engine speed to return to idle until the fifteen minute break-in period at 1200-1600 rpm has been completed.

                                                                             The AERA Technical Committee

                                               Oil Consumption On
                                    1989-94 Mazda 3.0L VIN JE Engines

The AERA Technical Committee offers the following information on oil consumption on 1989-94 Mazda 3.0L VIN JE engines. The area of concern causing this oil consumption is the cylinder head. At this time, only the single 
overhead cam (SOHC) heads have been affected. It appears this cylinder head is prone to cracking on the valve spring side of the head as mentioned in AERA Technical Bulletin TB-1260.

In at least some of the instances reported a dissimilar crack as described in TB 1260 has been observed. These cracks have allowed oil to enter the combustion process around either valve guide. These cracks create a passage 
for hot engine oil to seep through the openings or voids created. Engine oil collects in this area of the head, allowing ample amounts of oil to pass. There have been reports of one quart of oil consumed in 50 miles driven.

The extent of these cracks in most instances has been too excessive to warrant successful welding repairs as some have been reported to be longer than 6 inches. In other instances where the cracks have not been so severe but 
leakage was detected, welding has provided a successful repair.

                                                                            The AERA Technical Committee

                                Cleaning Engine Coolant From
                                The Lubrication System

The AERA Technical Committee offers the following information on removing engine coolant from the lubrication system. The following information applies only to certain situations and is not applicable for all engines. These procedures may be attempted if no engine bearing damage is detected on an engine that has been running with coolant in the oil.

Occasionally, an engine may continue operating with coolant in the lubricating oil supply reservoir for an extended period of time. Depending upon the amount of coolant and the amount of time involved, serious engine damage may not 
result immediately. In only those cases, the following cleansing operation may prove beneficial. Follow the steps listed below. 

1. Determine the source and cause of oil contamination and eliminate it.
2. Drain all oil from the engine oil system (including coolers and lines).
3. Remove and discard oil filter(s) and replace with new ones. 
4. Remove crankcase breather element.
5. Mix a 2:1 solution of a commercially available cleaning solvent such as Butyl Cellosolve (Union Carbide), Downol E-13 (Dow Chemical), or Glycol Ether E-B (Chem Central) or equivalent with the engine?s recommended  oil. (Follow all safety concerns on the solvent containers.). 
6. Add mixed solution to engine crankcase. Start and run engine at 1000-1200 RPM with no load applied for 30 minutes. Observe oil pressure often, discontinue procedure if pressure drops below 15 psi (103 kPa).
7. Repeat steps, 2 - 3 and 5 - 6 for the second time.
8. Repeat steps, 2 - 3 and 5 - 6 for the third time.
9. Drain all oil from the engine oil system (including coolers and lines).
10. Remove and discard oil filter(s) and replace with new ones. 
11. Fill crankcase with the appropriate amount of recommended engine oil and install a new crankcase breather element.

It is also recommended to perform the above mentioned procedures in a timely manner to allow the engine oil temperature to remain close to operating conditions. After the above procedures have been carried out, check the engine 
oil pressure. The engine may be placed back in service if those pressures are within the engine manufacturer's requirements.

                                                                             The AERA Technical Committee

                                                   Engine Over Cooling 
                                   On 1994-97 Mazda 2.3L VIN A Engines

The AERA Technical Committee offers the following information on engine over cooling on 1994-97 Mazda 2.3L VIN A engines. Some customers have complained there is insufficient heat coming from the heater in the cab of the vehicle.

One cause of this type of condition may be a casting slag from the cylinder head that has become lodged in the thermostat housing. When this occurs, the 
thermostat is unable to close completely. That opening allows the engine to over cool or never warm up to the correct operating temperature. To repair this problem, flush the entire cooling system (engine and radiator) to remove any slag that could be left in the engine.

To cure this problem at the factory, Mazda revised the cylinder head casting process during the 1997 model year. 

                                                                The AERA Technical Committee