Engine Running
Valve Train Analysis - Engine RunningNOTE: Static checks (engine off) are to be made on the engine prior to the dynamic analysis.
Prior to performing any dynamic checks, make sure the transmission is in P (Park) (A/T) or N (Neutral) (M/T) and the parking brake is fully engaged.
Start and idle the engine. Check for proper operation of all parts.
1. Check for plugged oil feed holes in the cylinder head.
2. Check for proper valve train lubrication.
Valve Train Analysis -- Engine Running, Rocker Arm
1. Check for plugged oil in the rocker arms or cylinder head.
2. Check for proper overhead valve train lubrication.
If insufficient oiling is suspected, accelerate the engine to 1200 rpm ± 100 rpm with the transmission in NEUTRAL and the engine at normal operating temperature. Oil should spurt from the rocker arm oil hole such that valve tips and rocker arms are well oiled and/or, with the valve covers off, oil splash may overshoot the rocker arms. If oiling is insufficient for this to occur, check the oil passages for blockage.
Valve Train Analysis, Engine Running, Push Rods - 3.0L Engine
1. Check for bent push rods and restriction in the Oil passage.
Camshaft Lobe Lift
Inspect the camshaft lobe lift. Replace the camshaft if the lobe lift is not within specification. Refer to Mazda B-Series Engine Workshop Manual.
Camshaft Lobe Lift - (3.0L Engine) (Push Rod)
Check the lift of each lobe in consecutive order and make a note of the readings.
1. Remove the valve covers. See VALVE COVER - RH REMOVAL/INSTALLATION - 3.0L, for 3.0L engine.
2. Remove the bolts, the rocker arm seat, and the rocker arms.
3. Make sure the valve tappet is seated against the camshaft. Install a suitable Dial Indicator with Bracketry (A) so the ball socket adapter of the indicator is on top of the valve tappet or Cup Shaped Adapter (B) is on top of the push rod and in the same plane as the valve tappet push rod movement.
4. Remove the spark plugs. See SPARK PLUG REMOVAL/INSTALLATION.
5. Connect a remote starter switch in the starting circuit. Crank the engine with the ignition switch in the OFF position. Bump the crankshaft over until the valve tappet is on the base circle of the camshaft lobe. At this point, the valve tappet will be in its lowest position. If checking during engine assembly, turn the crankshaft using a socket or ratchet.
6. Zero the dial indicator. Continue to rotate the crankshaft slowly until the valve tappet is in the fully-raised position (highest indicator reading).
NOTE: If the lift on any lobe is below specified service limits, the camshaft and valve tappet operating on the worn lobes must be replaced. as well as any valve tappet showing roller wear or needle bearing damage.
7. Compare the total lift recorded on the dial indicator with specification.
8. To check the accuracy of the original dial indicator reading, continue to rotate the crankshaft until the indicator reads zero.
9. Remove the dial indicator, adapter, and remote starter switch.
CAUTION: After installing the rocker arms, do not rotate the crankshaft until the valve tappets have had sufficient time to bleed down. To do otherwise may cause serious valve damage. Manually bleeding-down valve tappets will reduce waiting time.
10. Install the rocker arm seats, the rocker arms, and the bolts. Refer to Mazda B-Series Engine Workshop Manual.
11. Install the valve covers. See VALVE COVER - RH REMOVAL/INSTALLATION - 3.0L, for 3.0L engine.
12. Install the spark plugs. See SPARK PLUG REMOVAL/INSTALLATION.
Camshaft Lobe Lift - Valve Tappet, 2.3L, 3.0L and 4.0L Engines
Valve tappet noise may be caused by any of the following:
- excessive valve tappet gap.
- sticking valve tappet bucket.
- air in lubrication system.
Excessive valve tappet gap may be caused by excessive wear on valve tappet face or shim. Check gap between valve shim and camshaft to determine if any other valve tappet parts are damaged, worn or out of adjustment. Valve clearances are adjustable on the 2.3L engine. See VALVE CLEARANCE INSPECTION/ADJUSTMENT - 2.3L.
Air bubbles in the lubrication system will prevent the valve tappet from supporting the valve spring load. This may be caused by incorrect oil level or by air being drawn into the system through a hole, crack or leaking gasket on the oil pump screen cover and tube.
Timing Chain - 2.3L, 3.0 and 4.0 Engines
See TIMING CHAIN REMOVAL/INSTALLATION - 2.3L, see TIMING CHAIN REMOVAL/INSTALLATION - 3.0L, or see TIMING CHAIN REMOVAL/INSTALLATION - 4.0L, for the removal and installation of the timing chain and sprockets.
Make sure the timing marks on the crankshaft sprocket and the camshaft sprocket are positioned across from each other as shown in the illustration.
Timing Chain Deflection - 3.0L Engine
1. Remove the engine front cover. See TIMING CHAIN REMOVAL/INSTALLATION - 3.0L, or See ENGINE FRONT COVER REMOVAL/INSTALLATION - 4.0L.
2. Rotate the crankshaft so the camshaft sprocket and crankshaft sprocket timing marks line up.
3. Mark the top link(s) of the timing chain/belt.
4. Have an assistant hold the crankshaft sprocket with a suitable tool so it cannot turn.
5. Place a machinist's scale above the timing chain (camshaft sprocket) to measure its movement.
6. Put a torque wrench and socket on the camshaft sprocket bolt.
7. Apply a maximum of 20 N.m {2 kgf.m, 15 ft.lbf} torque in a clockwise direction.
8. Note the location of the marked link on the scale.
9. Apply a maximum of 20 N.m {2 kgf.m, 15 ft.lbf} torque in a counterclockwise direction while measuring the amount the marked link moves.
10. If movement is excessive, replace the timing chain, see TIMING CHAIN REMOVAL/INSTALLATION - 3.0L, for 3.0L engine, see TIMING CHAIN REMOVAL/INSTALLATION - 4.0L, for 4.0 engine.