The engines used in all Subaru models have received major changes and upgrades in the past few years, and some completely new engines have also been introduced. We’ll explain the changes, especially as they relate to your vehicle service efforts.

2.2 Liter Phase 1Engine Enhancements

The 2.2 liter Phase 1 engine has been enhanced, starting with 1997 model year. The single overhead camshaft (SOHC) engines have had internal and external changes that yield an approximately 10% increase in power and 3% increase in fuel economy. Accomplishing this involves many factors, one of which is engine friction reduction.

The piston, a major source of engine friction, has been coated with a friction reducing agent called molybdenum. This thin coating not only allows a smoother travel through the cylinder but also reduces cylinder wall scuffing. This coating will wear off over time and is not an indication of a problem.

The skirt of the piston has been reshaped and the overall weight has been reduced by approximately 100 grams. Compression ratio has been increased to 9.7 to 1 by reshaping the crown of the piston. This eliminates the clearance that was available between the piston at TDC and a fully opened valve. Piston pin offset has been changed to 0.5 mm. Piston to cylinder wall clearance has been reduced by increasing the piston diameter.

Another source of engine friction is the valvetrain. Hydraulic lash adjusters are always in contact with the camshaft or valve rockers. The hydraulic pressure of the lash adjuster must be overcome during operation and engine starting. To overcome this situation and to contribute to the total reduction of friction loss, the SOHC engines have solid valve adjusters.

The scheduled service of these valvetrains is set at 100,000 miles. The SOHC engine uses an adjustment screw and locknut. Follow the instructions below for setup and adjustment. Tools required for 2.2 valve adjustment are: thickness gauge, 10mm wrench, stubby standard screwdriver, crankshaft wrench.

Step 1

Remove the right bank camshaft outer cover. Standard value clearance:

• Intake valves 0.20 ± 0.02 mm
• Exhaust valves 0.25 ± 0.02 mm.

Rotate the engine until the arrow on the camshaft sprocket is at 12:00. The camshaft sprocket has an arrow and a mark for belt timing. Make certain the arrow is used, not the mark for valve adjustment only.

Using a standard thickness gauge, measure the clearance of the intake and exhaust valves on cylinder 1 only. Adjust the clearance by loosening the locknut and turning the adjustment screw until the proper clearance is obtained.

Step 2

Rotate the engine until the arrow on the camshaft sprocket is at 3:00. Check and adjust the clearance of the intake and exhaust valves on cylinder 3 only.

Step 3

Rotate the engine until the arrow on the camshaft sprocket is at 6:00. Check and adjust the clearance of the intake and exhaust valves on cylinder 2 only.

Other Engine Modifications

The intake manifold has been reshaped to increase the airflow mass and speed, contributing to improved low and mid engine speed operation. Components located on the intake manifold have been relocated as compared to the 1996 models. EGR Solenoid, Purge Control Solenoid, etc.

1999 2.2 Liter Phase 2 Engine Enhancements

All 2.2 liter engine for 1999 are the Phase 2 design. The 2.2 liter Phase 2 engines are a SOHC design, with a newly-designed cylinder head. Changes in the 2.2 liter Phase 2 engines are as follows:

• The engine and transmission are fastened with six bolts and two studs.
• The thrust bearing has been moved to the number 5 position.
• The oil groove in the number 1 and 3 have been changed to supply additional lubrication to the crank journal.

Additional Phase 2 Engine Features

• The cylinder head is a two-rocker shaft, solid type valve system with roller followers.
• The valves are positioned at a larger angle than previous model years. The intake valves are positioned 23 degrees off-center with the exhaust valves positioned 20 degrees off-center. Prior model year engines utilized a 15-degree positioning angle.
• Head gasket thickness is 0.7 mm.
• The intake rocker arms are marked so they are correctly placed on the rocker shaft when servicing. An IN1 or IN2 will be embossed on each rocker arm. As viewed from the front of the engine the Number 1 intake valve of each cylinder and the number 2 intake valve have an IN1 marked and IN2 marked rocker arm that mates with it. New IN1 rocker arms can also be identified by a Green painted mark on the top of the rocker arm. The IN2 rocker arms have a white mark. Proper positioning is maintained through the use of a wave washer located between the rocker shaft arm and rocker arm shaft support.
• The camshaft is secured to the cylinder head with the camcase. An oil passage in the cylinder head provides the passageway in the camcase with oil that leads to the intake rocker shaft. Oil from the camshaft is collected on the opposite side of the passageway leading to the intake rocker shaft to provide oil to the exhaust rocker shaft.
• Sealing of the camcase is accomplished by using a thin layer of Three Bond (1280B) applied in the channel around the camcase edge. After the three bond is applied, the camcase must be installed to the cylinder head and onto the engine before the three bond has time to cure. Failure to do this will result in oil leaks.

Note: Cylinder head and camcase must be replaced together (line bored).

• The sparkplug pipe is pressed into the cylinder head and is not serviceable. If it becomes damaged the cylinder head must be replaced. The seals installed onto the ends of the sparkplug pipes seal against the valve covers and should be replaced when the valve cover is removed.
• Timing belt marks for the left bank are on the inner timing belt cover and the edge of the camshaft sprocket. The crankshaft timing mark remains on the reluctor with engine block mark, just below the crank angle sensor. The right bank camshaft sprocket has a mark at the edge that is matched with the seam line formed by the meeting of the camcase and cylinder head (12:00 position).
• The right bank timing mark can be checked with outer cover in place using the provided window.
• Pistons on the 2.2 liter engines have a 0.5 mm offset with the engine having a compression ratio of 10.0 to 1. The horsepower has increased to 142 hp @ 5600 RPM. Maximum torque is149 ft. lbs @ 3600 RPM.
• The 2.5 liter engine uses double overhead camshafts that are belt-driven. Belt tension is maintained through the use of the hydraulic tensioner which is also used on the 2.2 and 3.3 liter engine.
• Camshaft sprockets are constructed of a resin type material with a metal key pressed into the sprocket for maintaining proper sprocket to shaft orientation.

The timing marks on the left bank intake camshaft sprocket are positioned at 12 o’clock and 6 o’clock. The 12 o’clock mark, which aligns with a timing mark on the timing belt housing, is used for camshaft to engine timing. The 6 o’clock mark is used for timing the intake camshaft to the exhaust camshaft, which has a timing mark at the 12 o’clock positions. The remaining timing mark on the exhaust camshaft sprocket, positioned at the 3 o’clock, ensures the exhaust camshaft sprocket is timed correctly to the engine. With all timing marks aligned, the intake and exhaust camshaft are in a loaded state. If the timing belt were removed, the camshafts would suddenly revolve from the force of the valve springs. To prevent this from occurring maintain the intake camshaft position and carefully unload the camshaft by allowing it to slowly rotate counterclockwise, (exhaust clockwise) while removing the belt.

Note: Use special tool J-42908 for holding camshaft sprockets during belt installation. It may also be used for loading as well as unloading the camshafts. Caution: valve damage will occur if both camshafts are turned incorrectly after the timing belt has been removed.

• The right bank intake sprockets timing marks are similar in location and purpose to the left bank. However, the exhaust camshaft sprocket on the right bank uses a timing mark at the 9:00 o’clock position to ensure proper camshaft to engine timing.
• To access the cylinder head bolts, the camshafts must be removed. Follow the procedure outlined in the Subaru service manual for performing this task. The camshafts are held to the cylinder head with bearing caps that are marked (right side) I1TD, I3TD, E1TD, E3TD.
• 2.5 liter engine head gaskets are identified by the three notches located along the gaskets edge, 2.2 liter normally aspirated engine head gaskets have only two notches.

Caution: The bolt patterns for both gaskets are the same but are not interchangeable.

• The cylinder head bolts for the 2.5 liter engine are much shorter than those of the 2.2 liter engine, and are not interchangeable.
• Valve servicing is accomplished by utilizing special tool 499718000 and a universal valve spring compressor. The single valve spring is color coded red and rests on a metal spring seat which is used to prevent cylinder head wear . A special tool (498267700) is required to adjust valve guide height, if replacement is necessary. A valve guide reamer (499767400) and a valve guide remover (499767200) will also have to be used. The hydraulic lash adjuster is of the same type as the 3.3 liter engine and requires no servicing.
• Spark plugs for the 2.5 liter engine are platinum tipped, NGK PFR5B-11. (Same maintenance schedule as the SVX.) 2.2 liter engines use Champion RC10YC4.
• Engine oil viscosity for all ‘96 Legacy and Outback vehicles is 5W-30 to improve fuel economy.

2.5 Liter Engine Spark Plug Replacement Procedure

1. Remove battery, washer tank and air cleaner.
2. Remove high tension cords.
3. Cover ATF pipes and ABS pipes with cloth to prevent them from damage during replacement of spark plugs.
4. Remove spark plugs by using a general service tool with the special instruction described below.

Installation

1. Set the spark plug into the socket.
2. Tighten the spark plug in the cylinder head with the socket. It is necessary to support the end of the socket by a finger.
3. When the spark plug can be felt to be tightened with 2 or 3 rotations, remove the socket from the spark plug.
4. Confirm if the spark plug is screwed into the hole properly by touching it with a finger. If it is difficult to touch it by finger, confirm its condition by using mirror.
5. Reset the socket on the plug then tighten it with the proper torque.
6. Install high tension cords.
7. Install battery, washer tank, and air cleaner.

Note: Length L1 (100mm, 3.94”) is most important for ease of removal and installation. Wrap points A & B with tape to prevent them from separating during work. An approximate 250mm extension bar is recommended between the ratchet and the universal joint.

1997 Phase 1 2.5 Liter DOHC Engine

The double overhead camshaft engines have had internal and external changes that yield an approximately 10% increase in power and 3% increase in fuel economy. Compression ratio has been increased to 9.7 to 1 by reshaping the crown of the piston. This eliminates the clearance that was available between the piston at TDC and a fully opened valve. Piston pin offset has been changed to 0.5 mm. Piston to cylinder wall clearance has been reduced by increasing the piston diameter.

Another source of engine friction is the valvetrain. Hydraulic lash adjusters are always in contact with the camshaft or valve rockers. The hydraulic pressure of the lash adjuster must be overcome during operation and the most critical time of engine start. To contribute to friction reduction, all DOHC engines have solid valve adjusters.

The scheduled service of these valvetrains is set at 100,000 miles. The DOHC engine uses an adjustment shim. There are 94 shim sizes.

Note: Use a thin nonmagnetic tool placed in the notch of the lash adjuster to remove shim (special tool J-43979).

Note: The printed size of the shim should be installed away from the camshaft lobe.

The space between the valvetrain and the frame rail of a DOHC is somewhat limited, however valve adjustment is possible by performing the following:

Step 1

• Set the crankshaft sprocket at 0 degrees. (use crankshaft wrench)   
• Set the left intake camshaft sprocket arrow at 12 o’clock. The camshaft sprocket has an arrow and a mark used for belt timing. Make certain to use the arrow and not the mark for valve clearance check.
• The engine is now set to check the clearance of the exhaust valves on cylinders 1 and 3 only. (Please remember that the profile of a camshaft with solid lifters has a ramp that is used to gradually take up the clearance between the lift of the lobe and the lash adjuster.)
• Measure and record the clearance.

Step 2

• Rotate the crankshaft 180 degrees.
• The left intake camshaft arrow should now be at 3 o’clock.
• Check the clearance of the intake valves on cylinders 1 and 3 only.
• Record the measurement.

Step 3

• Rotate the crankshaft 180 degrees.
• The left intake camshaft arrow should now be at 6 o’clock.
• Check the clearance of the exhaust valves on cylinders 2 and 4 only.
• Record the measurement.

Step 4

• Rotate the crankshaft 180 degrees.
• The left intake camshaft sprocket arrow should now be at 9:00.
• Check the clearance of the intake valves on cylinders 2 and 4 only.
• Record the measurement.

Step 5

• Use the formula below to choose the new shim:

Intake valve S = V + T – .20
Exhaust valve S = V + T – .25
S = Shim thickness to be used
V = Measured valve clearance
T = Shim thickness in use Standard valve clearance
(Intake valves 0.20 ± 0.02 mm)
(Exhaust valves 0.25 ± 0.02 mm)

Example: To solve for the new shim or T:

• Cylinder 1 intake measured valve or clearance is 0.22 mm – no adjustment needed.
• Cylinder 1 exhaust measured valve or clearance is 0.15 mm – adjustment needed.
• Cylinder 3 intake measured valve or clearance is 0.31 mm – adjustment needed.

The shim in use on cylinder 1 exhaust is marked 240. This refers to the shim having a thickness of 2.40 mm.

T = 2.40 S = V + T (0.25 mm)
V = 0.19 S = .19 + 2.4 – (0.25mm)
SVC = 0.25 ± 0.03 S = 2.59 – 0.25mm
(Standard valve clearance) S = 2.34

The shim in use on cylinder 3 intake is marked 245.This refers to the shim having a thickness of 2.45 mm.

T = 2.45 S = V + T (0.20mm)
V = 0.31 S = .31 + 2.45 – ( .20mm)
SVC = 0.20 ± 0.03 S = 2.76 – .20mm
(Standard valve clearance) S = 2.56

Step 6

• The current method of shim replacement is accomplished by removing the camshafts.

Caution: Follow the directions provided in the appropriate service manual for camshaft removal and belt installation.

Note: Special tool 498187100 may also be used for this procedure.

1999 2.5 Liter Engine Enhancements: DOHC (Phase 1) and SOHC (Phase 2)

The engines for the 1999 Subaru line are designated Phase 1 and Phase 2. 2.5 liter Legacy engines are the Phase 1 design, while the Impreza and Forester utilize Phase 2 design 2.5 liter engines. The 2.5 liter Phase 2 engines are SOHC engine with a newly designed cylinder head. The (Phase 1) 2.5 liter engine uses the same cylinder head configuration that it has used on prior year models with the crankcase and bell housing sharing the same characteristics of the new Phase 2 engines.

2.5 Liter (Phase 2) SOHC Engine Features

• The cylinder heads have a two-rocker shaft roller solid-type valve system.
• The valves are positioned at a larger angle than previous model years. The intake valves are positioned 23 degrees off center, with the exhaust valves positioned 20 degrees off center. Prior model year engines utilized a 15-degree positioning angle.
• Head gasket thickness is 0.7 mm.
• The intake rocker arms are marked for correct installation on the rocker shaft. An IN1 or IN2 is embossed on each rocker arm. As viewed from the front of the engine, the number 1 intake valve of each cylinder and the number 2 intake valve have an IN1 marked and IN2 marked rocker arm that mates with it. New IN1 rocker arms can also be identified by a green painted mark on the top of the rocker arm. The IN2 rocker arms have a white mark. Proper positioning is maintained through the use of a wave washer located between the rocker shaft arm and rocker arm shaft support.
• The camshaft is secured to the cylinder head with the camcase. An oil passage in the cylinder head provides the passageway in the camcase with oil that leads to the intake rocker shaft. Oil from the camshaft is collected on the opposite side of the passageway leading to the intake rocker shaft to provide oil to the exhaust rocker shaft.
• Sealing of the camcase is accomplished by using a thin layer of Three Bond applied in the channel around the camcase edge. After the three bond (1280B) is applied, the camcase must be installed to the cylinder head and onto the engine before the three bond has time to cure. Failure to do this will result in oil leaks.

Note: The cylinder head and camcase must be replaced together (line bored).

• Timing belt marks on the left bank are on the inner timing belt cover and the edge of the camshaft sprocket. The crankshaft timing mark remains on the reluctor, with the engine block mark just below the crank angle sensor. The right bank camshaft sprocket has a mark at the edge that is matched with the seam line formed by the meeting of the camcase and cylinder head (12:00 position).
• The right bank timing mark can be checked with outer cover in place, using the provided window.
• Piston design on the 2.5 liter engine remains the same as the 2.2 liter. The compression ratio is 9.7 to 1.

3.0 Liter Engine Features

The EZ-3.0 is the model name (engine designation) for the new six-cylinder engine introduced for the 2001 model year Legacy. The design idea for this engine was to create a power plant that could utilize the current body style, provide more power and decreased exhaust emissions. Many of the features refined for the current four-cylinder engine are employed on the EZ-3.0. However, new features such as Variable Intake Control and timing chain driven camshafts give the new engine a look and operation all of its own.

The front of the engine features a large front timing chain cover, secured to the inner cover with 59 bolts. There are four different lengths used and is sealed to the inner cover with Three Bond (1280B). Special care must be used when servicing the timing chain covers to ensure the proper length bolt and sealing procedures are used. A single serpentine belt provides the power to turn all engine accessories. Tension to the belt is controlled with an automatic tensioner. Replace the serpentine belt when the indicator is at or beyond this line.

Additional 3.0 liter engine features:

• Two radiator hose connections are located at the top of the engine block, connecting to each of the cylinder heads.
• An oil cooler is used to assist with bringing the oil to operating temperature.
• Direct ignition coils are fitted. The igniter and current control circuits are integrated.
• The lower hose is located on the thermostat housing, connecting to the lower section of the radiator. The thermostat is housed in the oil pan extension case. The oil pan is much smaller than previous model engines and contains a small magnet to collect metallic debris.
• Connections for the crankcase ventilation system are located at the top of the valve cover. Pressure is equalized from the right bank with a cross over tube.
• The new crank angle sensor, reluctor, and EGR pipe. The crank angle sensor and reluctor have been moved to the rear of the crankshaft. The EGR pipe has a new design and is mounted on the left bank of the engine.

3.0 Liter Engine Disassembly

• Begin disassembly by unloading and removing the serpentine belt.
• Remove the fuel rail protectors from both sides.
• The lower alternator bolt must be backed out before the manifold can be removed.
• Remove the alternator, compressor and power steering pump.

Note: The compressor is equipped with a speed sensor that sends a signal to the ECM. If the compressor speed drops more than 20% compared to the engine speed, the ECM turns the compressor off through the a/c relay. The refrigerant must be evacuated before removing the sensor.

• Remove the crankshaft bolt cover, bolt and harmonic balancer. Use caution to avoid losing the O-ring that seals the crankshaft bolt cover to the harmonic balancer.
• Begin removing the outer cover bolts. Keep them organized to ease reassembly. The bolts must be removed in the proper sequence to avoid warping the outer case.
• The timing chain on the EZ-3.0 is designed to last the life of the engine. Proper engine oil maintenance is necessary to ensure its longevity. Two chains are used. Four (4) camshaft sprockets, one (1) crankshaft sprocket, two (2) idler sprockets and the water pump complete the timing chain routing.
• The timing chain is sprayed with oil from a jet located on the oil pump relief valve housing.

Caution: the sprocket teeth are sharp. Use extreme care when working around or near them.

• The right bank camshafts are in a loaded state when the keyways are at 12:00. They must be unloaded in the proper way to prevent damage to the pistons and valves.
• Timing marks are located on the camshaft sprockets and the crankshaft sprocket. Marks and letters on the idlers are manufactures markings and are used only to establish which side faces outward. Do not use them to establish proper chain timing.
• The left bank camshaft sprockets are interchangeable when new. It is recommended they be returned to their original positions to maintain wear patterns after being used.
• The left timing chain is the longer of the two with 148 links. The right chain has 134 links.
• Turn engine clockwise to rotate it until the key ways of the cam sprockets are at the 12:00 position. Remove the right bank tensioner, chain and chain guides.
• Remove the left bank tensioner, chain and chain guides.

Note: Turn the crankshaft 90 degrees counter clockwise to reduce the chance of accidental damage to the pistons and valves in the event the camshafts suddenly unload.

• The left bank is currently unloaded. The right bank is loaded and must be unloaded using the following procedure.

Unloading Cam Sprockets

• Position the camshaft sprocket wrench on the right bank intake sprocket and turn 90 degrees counter clockwise.
• Position the camshaft sprocket wrench on the right bank exhaust sprocket and turn 90 degrees clockwise. Both camshafts are now unloaded.
• Remove both the intake and exhaust camshaft sprockets on the left and right banks.
• Remove the bolts from the water pump.
• Thread two eight millimeter bolts as shown and equally turn them in. This will assist with the removal of the pump. Remove the O-ring that seals the water pump to the inner cover.

Valvetrain Construction

The camshafts are composed of carbon steel pipes with sintered metal lobes. During construction, the lobes are positioned on the pipe using a sintered metal paste. The camshafts are then baked until the paste is hardened. The lobes of the camshafts are offset by 1 millimeter to rotate the camshaft bucket and shim, to reduce wear.

The right bank intake camshaft has a reluctor built onto the end. The new camshaft sensor uses this reluctor to help determine injection and ignition timing.

The valve adjustment procedure is the same as other DOHC Subaru engines however a new tool has been designed to work specifically on the EZ-3.0 engine. The tool is a wedge fitted into place over the two shims requiring removal.

Some adjustment will be required to properly seat the bucket depression finger. Turning the top bolt pushes the fingers down allowing room for the shim to be removed.

Chain Tensioners

The chain tensioners are fed oil pressure from the engine oiling system. The supplied pressure combined with spring tension keeps the timing chains operating at the correct tension.

Note: The left bank and right bank tensioners are not interchangeable.

The worm gear assemble and spring tension keep tension on the chains with the engine off, eliminating any tension problems that could occur during engine start up. The tensioners are turned in by hand for reassembly. Observe the order of the worm gear assemble. Make sure your hands are dry when depressing the tensioners. A rivet or large paper clip will hold tensioner in place. Do not use a press to depress the tensioner.

Oil Pan Removal

• Remove the oil pan bolts and oil pan. Observe that the oil pan has a different design from four cylinder Subaru engines. Note the placement of the bolts.
• Remove the oil pan extension housing bolts. There are 28 bolts with five different lengths. Follow the proper sequence to prevent warping the case. Confirm the O-ring placement.