FUSO 4M4 – Engine – CYLINDER HEAD AND VALVE MECHANISM

Assembly sequence
Follow the disassembly sequence in reverse.

Removal: Cylinder head
• Loosen the cylinder head bolts (M10: 1, 2), (M12: 3 to 20) by turns in the order indicated in the illustration before they are removed in the same order.

• With the timing chain kept attached to the cam sprocket, remove the cylinder head by lifting it straight up.
• After removing the cylinder head, hold the cam sprocket using. Be careful not to drop the timing chain.

Removal: Cylinder head gasket

Installation: Cylinder head

• The cylinder head gasket is a selective use part. Choose the gasket according to the following procedure.
• Measure the amount of piston projection for every cylinder. (See the PISTON AND CONNECTING ROD section.)
• After the measurement, select a cylinder head gasket with the thickness appropriate for the average amount of piston projection from the following table.
• If any cylinder has a piston that has the amount of projection greater than the maximum value of the average piston projection amount by 0.05 mm or more, use a gasket a rank thicker (A→B, B→C, C→D).

• The size class of the cylinder head gasket can be determined from the number of notches on the gasket edge.

• Clean the sealant application surfaces of each part.
• Apply sealant to the top surfaces of the areas where the timing gear case, the front plate and the upper crankcase join together (two locations).
• Install the cylinder head together with the cylinder head gasket on the crankcase within three minutes of applying the sealant, being careful not to dislodge the sealant.

• Tighten the cylinder head bolts by following different tightening procedures for bolts 1 to 18 (M12) and bolts 19 and 20 (M10).
The bolts should be tightened in steps according to the following instructions.
• Install the cylinder head bolts with the shear droop (press punched edge) side of the washer on each of them facing in the indicated direction.

Tightening procedure for bolts 1 to 18
• Retighten the tightened cylinder head bolts (M12) to a torque of 49 N·m {5 kgf·m} in the order indicated in the illustration.
• After tightening, tighten the bolts further 90 degrees in the order indicated in the illustration.
• Then, tighten the bolts further another 90 degrees in the order indicated in the illustration.
• Finally, put a punch mark on the head of each bolt (M12) to indicate the number of times the bolt has been used.

Tightening procedure for bolts 19 and 20
• After completing the tightening procedure for bolts 1 to 18 (M12), tighten bolts 19 and 20 (M10) to 58 N·m {5.8 kgf·m}.

 

 

 

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