Mazda Training manual — part 24

Powertrain Engines

Valve Actuation

•

The camshafts actuate the valves via roller cam followers.

•

The valve clearance has to be measured between the roller cam follower and the cam
lobe, and is adjusted through the adjusting screw of the roller cam follower (refer to the
workshop manual for details).

NOTE: In order to prevent damage to the claw of the roller cam follower when loosening the

locknut of the adjusting screw, the cam lobe must push down the roller cam follower
firmly (refer to the illustration below).

•

The valve clearance has to be checked (and if necessary adjusted) for the first time after
20,000 km or 12 months (whichever occurs first). After that it has to be checked (and if
necessary adjusted) every 120,000 km or 6 years (whichever occurs first).

L1001.4_01077

1

Cam lobe

4

Roller cam follower

2 Adjusting

screw

5 Claw

3 Locknut

6 Roller

Curriculum Training

01-83

Engines Powertrain

Valve Train

•

The camshafts are driven via a timing belt by the fuel high-pressure pump pulley/gear,
which in turn is driven via helical gears by the crankshaft.

•

The timing belt and the timing belt tensioner have to be replaced every 120,000 km.

L1001.4_01078

1

Camshaft pulley

8

Crankshaft gear

2

Intake camshaft

9

Idler gear no.1

3 Exhaust

camshaft

10 Idler gear no.2

4

Roller cam follower

11

Fuel high-pressure pump pulley/gear

5 Balancer

shaft

12 Tensioner

pulley

6

Balancer shaft gear

13

Timing belt

7

Idler gear no.3

14

Idler pulley

01-84 Curriculum

Training

Powertrain Engines

•

The crankshaft gear and the fuel high-pressure pump gear are equipped with friction
gears. The spring-loaded friction gears eliminate the backlash between the meshing
gears, reducing gear noise.

NOTE: Before removing the fuel high-pressure pump gear, the friction gear must be fixed to

the fuel high-pressure pump gear using a detent bolt (M6 x 1.0, length approx. 16
mm) to prevent it from rotating due to the spring force.

L1001.4_01153

1

Hole for detent bolt

4

Friction gear

2

Fuel high-pressure pump gear

5

Helical gear

3 Spring

Curriculum Training

01-85

Engines Powertrain

Timing Belt Tensioner

•

The WL-C engine features a modified automatic timing belt tensioner with integrated
tensioner pulley. However, the operating principle is the same as on the RF-T engine.

L1001.4_01080

1

Tensioner rod

4

Plunger spring

2 Seal

5 Pressure

chamber

3 Plunger

6 Check

valve

•

For releasing the belt tension the timing belt tensioner has to be turned counterclockwise
with an Allen key, and secured by inserting a locking pin with 6 mm diameter (refer to the
workshop manual for details)..

NOTE: When removing the timing belt tensioner, the tensioner pulley must not be separated

from the tensioner housing.

NOTE: In case air has entered the pressure chamber of the timing belt tensioner, it must be

bled using a certain procedure (refer to the workshop manual for details).

L1001.4_01079

1

Apply force (max. 39 Nm)

3

Hole for locking pin

2 Mounting

bolts

01-86 Curriculum

Training