FUSO 4M4 – Engine – ON-VEHICLE INSPECTION AND ADJUSTMENT – Inspection and Replacement of Timing Chain

Tools marked with * are components of the timing chain tool set (MH063679).

[Inspection]
• Perform the following inspections. If there is any abnormality, replace the timing chain.
(1) Noise
• Run the engine and check for any abnormal noise caused by interference between piston and valve.
• If abnormal noise is heard, check the pistons and valves for possible interference. (See “CYLINDER HEAD AND MECHANISM”
and “PISTON AND CONNECTING ROD”.)
(2) Protrusion of chain tensioner’s plunger
• Measure the protrusion of the chain tensioner’s plunger to determine the elongation of the timing chain.
• Remove the chain tensioner from the cylinder head. The plunger is bounced a little out of the chain tensioner by the spring inside.
Prevent the plunger from falling.
• Measure the distance from the forward end of the plunger to the farthest wear mark. If the measured value exceeds the specified limit, replace the timing chain.

[Replacement]
• Remove the fan coupling, front engine hanger and rocker cover.
• To check the timing position, rotate the crankshaft pulley clockwise with and align the timing mark “0” on the timing gear case with the notch on the crankshaft pulley to bring the No. 1 cylinder piston to the top dead center (TDC) on the compression stroke. The No. 1 cylinder piston is at TDC if the protrusion on the camshaft is facing upward.

• With the No. 1 cylinder piston at TDC, check that the two mating marks “ ” on the cam sprocket are at the illustrated positions.

• Install on the cylinder head and tighten the bolts (M8 × 20 mm) firmly.
• Crank the engine by hand and bring the mark link plate (one plate) of the timing chain to the illustrated position of the cam sprocket.

• Remove the chain tensioner and its gasket from the cylinder head.
• Install on the cylinder head.

• Using, remove the pins of the mark link plate (one plate) from the timing chain. Then, remove the mark link plate and the plate from the timing chain.
• If the pins are difficult to remove, press them out by inserting the temporary link of the timing chain kit into the pin holes from the front side of the engine.

• With the mark link plate (two plates) of the new timing chain facing the front of the engine, connect the new timing chain with the unlinked end of the old timing chain using a temporary link and clip.
• Remove the shop towels from the timing chain.

• Slowly crank the engine by hand in the normal direction to rotate the timing chain so that the new timing chain takes the place of the old one.

• Stop cranking when the old timing chain is completely delivered and the temporary link comes to the illustrated position of the cam sprocket.
• Fill the space around the timing chain with shop towels again. Remove the temporary link and the timing chain.

• Remove from the cylinder head.

• Install a permanent link from the rear of the engine to connect the two ends of the new timing chain.
• Remove

• Crank the engine by hand until the permanent link comes to the illustrated position of the intake cam sprocket.

• Attach a mark link plate onto the punch of.
• Align the pins of the permanent link with the holes on the mark link plate to set.
• Tighten the bolt of until it cannot be tightened any further.

• Check that the pins of the permanent link project by the amount indicated in the illustration.

• Turn around 180 degrees and mount it so that the die is aligned with the mark link plate.
• Tighten the bolt of to approximately 64 N·m {6.5 kgf·m} and flatten the end of each pin of the permanent link.

• Check that the pin ends are flattened to the width indicated in the illustration.
• Remove the shop towels from the timing chain.

• Check that the new chain tensioner’s plunger is locked in place by the hook, then install it to the cylinder head with the new gasket. Make sure the sealant application surface of the gasket.

• Crank the engine in the normal direction (clockwise as viewed from the front of the engine). This unhooks the plunger, allowing the tension of the timing chain to be adjusted by the internal ratchet mechanism.

• With the No. 1 cylinder piston at TDC, check that the mating marks “O” on the cam sprocket are at the same place as before.
• Install the rocker cover and fan coupling.

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