Engine Mechanical - 2.5L: Other Mazda Tribute II

ENGINE - 2.5L

The 2.5L (153 CID) 4-cylinder engine has the following features

1. Dual overhead camshaft
2. Four valves per cylinder
3. Sequential multiport fuel injection (SFI)
4. Aluminum cylinder head
5. Aluminum cylinder block
6. Electronic ignition system with coil-on-plug 4 ignition coils

The 2.5L engine is a 4 valve-per-cylinder, dual overhead camshaft engine. The engine uses a coil-on-plug ignition system. The cylinder block is made of aluminum and the bearing caps are integrated into the ladder assembly. An aluminum oil pan bolts to the bottom of the lower cylinder block and to the transmission to provide greater strength. The camshafts are mounted in the cylinder heads and act against valve tappets to open and close the valves. The camshafts are driven off the front of the cylinder head by one timing chain. The chain is driven by a sprocket that is located on the crankshaft. The piston assembly is an aluminum piston with a cast iron connecting rod. The oil pump is driven by the crankshaft via a dedicated chain that is driven by the same sprocket that drives the timing chain.

Code Information

The engine code information label, located on the side of the valve cover and the front side of the valve cover, contains the following

1. Engine build date
2. Engine plant code
3. Engine code

Exhaust Emission Control system

Operation and necessary maintenance of the exhaust emission control devices used on this engine are covered in the Powertrain Control/Emissions Diagnosis (PC/ED) Service Information.

Induction System

The sequential multiport fuel injection (SFI) provides the fuel/air mixture needed for combustion in the cylinders. The 4 solenoid-operated fuel injectors

1. are mounted in the intake manifold.
2. meter fuel into the air intake stream in accordance with engine demand.
3. are positioned so that their tips direct fuel just ahead of the engine intake valves.
4. are connected in series with the fuel pressure sensor.
5. supply fuel from the fuel tank with a fuel pump mounted in the fuel tank.

A constant fuel pressure is maintained across the fuel injectors by the fuel pressure sensor

1. is positioned upstream from the fuel injectors on the fuel injection supply manifold.

Accessory Drive

The accessory drive

1. has a single serpentine belt with 6 ribs.
2. has automatic tensioning.
3. is not adjustable.

The accessory drive system provides power to operate components which power other systems. These could include components such as the generator, power steering pump and A/C compressor. Each of these components is equipped with a pulley which is driven by the accessory drive belt. The accessory drive belt is driven by the engine crankshaft pulley. One or more idler pulleys may be provided to facilitate belt routing and alignment. The automatic belt tensioner maintains correct belt tension and compensates for component wear and changes in system load. System load changes can be caused by the A/C compressor clutch engaging or disengaging, or demand changes on other systems powered by the accessory drive belt. To maintain correct operation of this system, it is critical that the correct length drive belt be installed. The pulleys must also be correctly aligned and kept clean.

Scheme 322

Belt Tensioner

Note. The accessory drive belt tensioner must be replaced as a complete unit.

Automatic tensioners are calibrated to provide the correct amount of tension to the belt for a given accessory drive system. Unless a spring or damping band within the tensioner assembly breaks, or some other mechanical part of the tensioner fails, there is no need to check the tensioner for correct tension.

Scheme 323

1. For additional information, see the procedures in this service information.

Scheme 324

1. With the vehicle in NEUTRAL, position it on a hoist. See «LIFTING»(ref-348626-S31954056142009112700000) .
2. Remove the pin-type retainer, 5 bolts and the RH splash shield. To install, tighten to 9 N.m {0.9 kgf.m, 80 in.lbf}.
3. Using the hex feature, rotate the accessory drive belt tensioner clockwise and remove the accessory drive belt from the water pump pulley. Remove the accessory drive belt from the engine.
4. To install, reverse the removal procedure.

INTAKE MANIFOLD EXPLODED VIEW - 2.5L

Intake Manifold (View 1 of 2)

Scheme 325

Intake Manifold (View 2 of 2)

Scheme 326

1. For additional information, see the procedures in this service information.

Scheme 327

1. For additional information, see the procedures in this service information.