Mazda Training manual — part 7

Powertrain Engines

Valve Train

•

The camshafts are driven by a maintenance-free pinned link timing chain.

L1001.4_01010

1

Exhaust camshaft sprocket

7

L3 engine

2

Timing chain

8

Chain guide

3

Intake camshaft sprocket

9

Crankshaft sprocket

4

L8, LF engine

10

Chain tensioner

5

Pitch size

11

Chain tensioner arm

6 Pin

Curriculum Training

01-15

Engines Powertrain

Timing Chain Tensioner

•

An automatic timing chain tensioner is fitted to ensure optimum chain tension over the
service life of the engine.

•

The timing chain tensioner operates using engine oil pressure. The ratchet and the rack
hold the piston in place when the engine is started.

L1001.4_01011

1

Hole for a ratchet lock

5

Plunger

2

Ratchet spring

6

Plunger spring

3 Ratchet

7 Check

valve

4

Rack

8

Oil supply hole

01-16 Curriculum

Training

Powertrain Engines

•

The timing chain tension can be released as following (refer to the workshop manual for
details):

1. Using a suitable screwdriver or equivalent tool, unlock the chain tensioner ratchet.

2. Turn the exhaust camshaft clockwise using a suitable wrench on the cast hexagon,

and loosen the timing chain.

3. Placing a bolt (M6 x 1.0) in the engine front cover upper blind plug hole, secure the

chain tensioner arm in the position where the tension is released.

L1001.4_01012

1

Direction of rotation

3

Detent bolt

2

Unlocking the chain tensioner ratchet

Curriculum Training

01-17

Engines Powertrain

Variable Valve Timing System

•

The variable valve timing system continuously varies the valve timing of the intake
valves, controlling the cylinder charge.

•

The camshaft actuator is attached to the camshaft sprocket and varies the position of the
intake camshaft in relation to the sprocket. The intake camshaft position is controlled by
the oil control valve using engine oil pressure.

NOTE: The camshaft actuator cannot be repaired due to its precise interior construction, i.e.

it must be replaced as a complete unit.

L1001.4_01140

1

Oil control valve

3

Camshaft actuator

2 Intake

camshaft

01-18 Curriculum

Training