Removal (Frontier, Pathfinder, QX4 & Xterra) 1. Disconnect negative battery cable. Remove the engine undercover. Drain coolant and remove the radiator. Remove engine cooling fan and water pump pulley. Remove accessory drive belts. Remove spark plugs. 2. Remove distributor protector. Remove A/C compressor drive belt idler bracket. Remove fresh air intake tube from rocker cover. Remove thermostat housing hose. 3. Rotate crankshaft to set No. 1 cylinder at TDC on compression stroke. See Fig. 1 . Remove crankshaft pulley bolt and remove crankshaft pulley. Remove front upper and lower timing belt covers. See Fig. 2 . 4. Align punch mark on left camshaft sprocket with punch mark on timing belt upper rear cover. Align punch mark on crankshaft sprocket with notch on oil pump housing. See Fig. 3 . Install crankshaft pulley bolt so that crankshaft can be rotated. 5. Loosen timing belt tensioner nut.
See Fig. 4 . Turn tensioner, and remove timing belt. Inspection (Frontier, Pathfinder, QX4 & Xterra) Check timing belt for cracks and broken or worn teeth. Check belt tensioner for smooth turning. Check condition of tensioner spring. Replace parts as necessary. Installation (Frontier, Pathfinder, QX4 & Xterra) 1. Install timing belt when engine is cold. Ensure No. 1 cylinder is at TDC on compression stroke. Crankshaft sprocket mark should align with mark on rear cover. See Fig. 5 . If removed, install timing belt tensioner and tensioner spring. NOTE: If stud for tensioner spring is removed, apply thread sealant to stud threads before installing. 2. Turn tensioner clockwise fully outward with hexagon wrench, and temporarily tighten lock nut. Align White lines on timing belt with punch marks on camshaft sprockets and crankshaft sprocket. See Fig. 6 . Point arrow on timing belt toward front belt cover. There should be 40 teeth between left and right camshaft sprockets, and 43 teeth between left camshaft sprocket and crankshaft sprocket. 3. If engine was overhauled or reassembled (rocker covers removed), go to step 6 . If only the timing belt was replaced, go to next step. 4. Loosen tensioner lock nut. Using hex wrench, turn tensioner clockwise and counterclockwise at least 2 times. Tighten tensioner lock nut.
Turn crankshaft clockwise at least 2 revolutions, then slowly set No. 1 cylinder at TDC on compression stroke. Apply 22 lbs. (10 kg) of force to belt (downward direction) midway between camshaft sprockets. Belt deflection should be 0.51-0.59″ (13-15 mm). If not, readjust belt tension. 5. Install lower and upper belt covers. Install crankshaft pulley. Tighten bolt to specification. See TORQUE SPECIFICATIONS . To complete installation, reverse removal procedures. Fill and bleed cooling system. See COOLING SYSTEM BLEEDING . Adjust drive belts to proper tension. 6. Loosen rocker shaft bolts to relieve belt tension caused by camshafts. Loosen tensioner lock nut. Using Allen wrench, rotate tensioner by turning Allen wrench clockwise 70-80 degrees. Temporarily tighten lock nut. Rotate crankshaft clockwise at least 2 revolutions. 7. Slowly return cylinder No. 1 to TDC of compression stroke. Using Push/Pull Gauge (J-38387), apply 22 lbs. (10 kg) of pressure to timing belt between right camshaft sprocket and tensioner. Hold tensioner in position with Allen wrench, and loosen tensioner lock nut. 8. Place a .0206″ (.5 mm) feeler gauge under tensioner pulley between pulley and timing belt, and rotate crankshaft clockwise until feeler gauge is centered between tensioner pulley and timing belt (timing belt will move about 2.5 teeth). See Fig. 7 . Tighten tensioner lock nut to specification. See TORQUE SPECIFICATIONS . 9. Rotate crankshaft to remove feeler gauge. Rotate crankshaft clockwise at least 2 revolutions, then slowly set cylinder No. 1 at TDC of compression stroke. While applying 22 lbs. (10 kg) of pressure, measure timing belt deflection halfway between camshaft sprockets. If deflection is not .51-.59″ (13-15 mm), repeat steps 6 -8 . To complete installation, reverse removal procedure. Fill and bleed cooling system. See COOLING SYSTEM BLEEDING . Adjust drive belts to proper tension.