Engine Mechanical - 2.5L: Adjustments Nissan Altima L31

TENSION ADJUSTMENT

1. Belt tension is not manually adjustable, it is automatically adjusted by the auto-tensioner.

Scheme 47

1. Remove front RH engine side cover.
2. With box wrench, and while securely holding the hexagonal part in pulley center of automatic tensioner, move the wrench handle in the direction of arrow (loosening direction of tensioner). CAUTION: Avoid placing hand in a location where pinching may occur if the holding tool accidentally comes off.
3. Insert a rod approximately 6 mm (0.24 in) in diameter through the rear of engine into holding boss to fix tensioner pulley. Leave tensioner pulley arm locked until belt is installed again.
4. Loosen auxiliary drive belt from water pump pulley in sequence, and remove it.

Adjustment

1. Perform adjustment depending on selected head thickness of valve lifter.
2. The specified valve lifter thickness is the dimension at normal temperatures. Ignore dimensional differences caused by temperature. Use the specifications for hot engine condition to adjust.

Scheme 48

Scheme 49

Scheme 50

1. Remove camshaft. Refer to «REMOVAL AND INSTALLATION»(ref-159291-S05711253782005042600000) .
2. Remove the valve lifters at the locations that are outside the standard.
3. Measure the center thickness of the removed valve lifters with a micrometer.
4. Use the equation below to calculate valve lifter thickness for replacement. Valve lifter thickness calculation. t=t1 + (C1 - C2) t=Thickness of replacement valve lifter. t1=Thickness of removed valve lifter. C1=Measured valve clearance. C2=Standard valve clearance. Intake : 0.36 mm (0.0142 in) Exhaust : 0.37 mm (0.0146 in) Thickness of a new valve lifter can be identified by stamp marks on the reverse side (inside the cylinder). Stamp mark 696 indicates a thickness of 6.96 mm (0.2740 in) Available thickness of valve lifter: 26 sizes with a range of 6.96 to 7.46 mm (0.2740 to 0.2937 in), in steps of 0.02 mm (0.0008 in), when assembled at the factory.
5. Install the selected valve lifter.
6. Install camshaft.
7. Manually turn crankshaft pulley a few turns.
8. Check that valve clearances for cold engine are within specifications, by referring to the specified values.
9. After completing the repair, check valve clearances again with the specifications for warmed engine. Use a feeler gauge to measure the clearance between the valve and camshaft. Make sure the values are within specifications. Valve clearance

Scheme 51

Scheme 52

Scheme 53

Scheme 54

Scheme 55

Scheme 56

Scheme 57

Scheme 58

Scheme 59

1. Support the engine and transaxle assembly with suitable tools.
2. Remove the upper and lower oil pan, and oil strainer. Refer to «Removal and Installation»(ref-159291-S26773553532005042600000).
3. Remove the IVTC (intake valve timing control) cover. Loosen bolts in the numerical order as shown. Remove the cover with suitable tool to cut the sealant.
4. Pull chain guide between camshaft sprockets out through front cover.
5. Set the No. 1 cylinder at TDC on the compression stroke with the following procedure: Rotate the crankshaft pulley clockwise and align the mating marks to the timing indicator on the front cover. see scheme 52 At the same time, make sure that the mating marks on the camshaft sprockets are lined up as shown. If not lined up, rotate the crankshaft pulley one more turn to line up the mating marks to the positions as shown.
6. Remove crankshaft pulley with the following procedure: Hold the crankshaft pulley with a suitable tool, then loosen the crankshaft pulley mounting bolt, and pull the pulley out about 10 mm (0.39 in). Attach a pulley puller in the M 6 (0.24 in diameter) thread hole on crankshaft pulley, and remove crankshaft pulley.
7. Remove the front cover with the following procedure: Loosen the mounting bolts in the reverse order shown in the figure, and remove them. Remove the front cover. CAUTION: Be careful not to damage the mounting surface.
8. If the front oil seal needs to be replaced, lift it out with a screw-driver to remove it.
9. Remove timing chain with the following procedure: Push in the tensioner plunger. Insert a stopper pin into the hole on the tensioner body to hold the chain tensioner. Use a wire of 0.5 mm (0.02 in) diameter as a stopper pin. Remove the chain tensioner. Secure hexagonal part of the camshaft with a wrench and loosen the camshaft sprocket mounting bolt and remove the camshaft sprocket for both camshafts. CAUTION: Do not rotate the crankshaft or camshafts while the timing chain is removed. It can cause damage to the valve and piston.
10. Remove the chain slack guide, tension guide, timing chain, and oil pump drive spacer.
11. Remove the timing chain tensioner for the balancer unit with the following procedure: Lift the tensioner lever up, and release the ratchet claw for installation. Push tensioner sleeve in, and hold it. Matching the hole on lever with the one on body, insert a stopper pin to secure tensioner sleeve. Remove the timing chain tensioner for the balancer unit.
12. Remove timing chain for balancer unit and crankshaft sprocket.
13. Loosen mounting bolts in reverse order shown in the figure, and remove balancer unit. Use Torx socket (size E14) CAUTION: Do not disassemble balancer unit.