Engine - Diesel Type Knocking Noise

87subaru2
NUMBER 02-56-87


DATE 10-26-87

APPLICABILITY 1987 TURBO VEHICLES (EXCEPT XT)

SUBJECT: TURBO ENGINE KNOCKING NOISE

If you encounter a customer complaint of a diesel type knocking noise coming from the engine compartment, first check the following VIN and engine range:

Note: This Bulletin supercedes and cancels Subaru Service Bulletin number 02-54-87, released 09-28-87.

VIN RANGE

4 DR - 200001 - 234616
Sta. Wagon - 400001 - 465716
3 DR Coupe - 800001 - 812190


ENGINE RANGE


Before Engine Number 405773 (up to March 1987 Production)

Note: This procedure only applies to vehicles within this range.

1. Diagnostic Procedure

This procedure is for diagnosing non-destructive engine sound levels on vehicles within the above range. Other engine noises can be diagnosed using the 1987 Subaru Service Manual Section 2-3, Page 51, "Engine Noise".

^ Set the emergency brake, chock the rear wheels and hold the foot brake.
^ Make sure the engine is at operating temperature and engine idle speed, timing, and cambelt tensioning are correct.
^ Manual transmission vehicles, rev the engine to approximately 1000-1200 RPM. Carefully release/slip the clutch with the transmission 1st gear. Try not to stall the engine. The diesel type noise should be audible.
^ Automatic transmission vehicles, rev the engine to approximately 1000-1200 RPM with the transmission in "DRIVE". The diesel type noise should be audible.
^ With the engine idling, and the transmission in "PARK" for automatics and neutral for manual transmissions, remove the #4 injector wire connector and the noise should diminish.
^ Disconnecting any of the other injector wiring connectors may increase the noise.

FIGURE 1:

2. Repair Procedure

If the vehicle is diagnosed as having an unacceptable level of the diesel type noise, it will be necessary to replace all four pistons with a slit type double recessed piston. See Figure 1.

FIGURE 2:

Step 1) Before removing the engine locate the block stampings indicating the piston type to be used. See Figure 2. PLACE THE PARTS ORDER FOR THE CORRECT PISTONS BEFORE DISASSEMBLY.


AFTER VERIFICATION THAT THE PARTS ARE AVAILABLE:

Step 2) Remove the engine according to the 1987 "L" Series Subaru Service Manual (Blue and White) Section 2-11 pages 4-9.

Step 3) Remove the cam covers, cam belts, intake manifold cylinder heads and related items according to Section 2-3 of the Service Manual mentioned above.

Step 4) Remove all four pistons according to Section 2-3 pages 33 and 34. Do not split the crank case.

FIGURE 3:

Step 5) Transfer the rings from each piston to the slit type double recess piston. Remember that the "R" or "N" markings on the first and second compression rings face upward to the top of the piston. See Figure 3 for the oil ring installation method.

Note: Ensure the piston rings stay with the cylinder they were removed from.

Note: Do not hone the cylinders.

Step 6) Install all four new pistons, pins and circlips in the reverse order of disassembly.

Step 7) Reassemble all remaining components in reverse order of disassembly and reinstall the engine according to the 1987 Subaru Service Manual Section 2-11 pages 16-20.


PISTON APPLICATION CHART

PISTON SIZE PART NUMBER

Piston, Pin and Circlip Assy. B 12006AA210

Piston, Pin and Circlip Assy. A 12006AA240

Piston, Pin and Circlip Assy. C 12006AA250


3. Warranty Information

This procedure can be claimed for vehicles within the terms of the Limited Subaru Warranty using the following information:

Operation No. A127-532 Failure Code AAV-58 Time: 9-1/2 Hrs.