W/Z24I Engine

1. Set main bearings in proper position on cylinder block, noting the following:
a. If crankshaft, cylinder block or main bearing is reused, it is necessary to measure main bearing clearance.
b. Only No. 3 bearing is flanged.
c. Bearing Nos. 2 and 4 are same type.
d. Bearing Nos. 1 and 5 are same type.
e. Upper and lower bearings are not interchangeable because upper bearings have oil groove.
f. On Pathfinder and Pickup, if crankshaft, cylinder block and main bearing are all replaced, It is necessary to select main bearings of proper thickness. If grade number of No. 1, 3 and 5 cylinder block main journal, stamped on cylinder block, is 0 select grade A bearing. If grade No. is 1, select grade B bearing. Use grade B bearing for Nos. 2 and 4 main journals.
2. Apply engine oil to main bearing surfaces on both sides of cylinder block and cap.

Fig. 11 Main bearing cap tightening sequence:

3. Install crankshaft and main bearing caps, torquing bolts to 33-40 ft. lbs. in two or three steps in sequence, Fig. 11, then ensure crankshaft turns smoothly by hand.
4. Ensure crankshaft endplay, measured at center bearing, is .002-.007 inch.
5. Measure connecting rod side clearance. If clearance is not .0079-.0118 inch, replace connecting rod and/or crankshaft.
6. Using suitable tool, install pistons with connecting rods, noting the following:
a. Be careful not to scratch cylinder wall with connecting rod.
b. Apply engine oil to cylinder wall, piston and bearing.
c. Arrange so that front mark on piston head faces to front of engine.
7. Install connecting rod bearing caps, torquing nuts to 33-40 ft. lbs.
8. Make sure the intalled components turn freely. If not, recheck your installation before proceeding.
9. Thoroughly clean cylinder block and cylinder head mating surfaces.
10. Turn crankshaft until No. 1 piston is at TDC on compression stroke.
11. When installing cylinder head be sure clearance exists between valves and piston heads. If necessary loosen valve adjustments to draw in valves.
12. Temporarily tighten 2 center head bolts slightly. Do not rotate camshaft or crankshaft independently when performing the proceeding steps.
13. Install crankshaft sprocket with timing mark facing front of engine.
14. Install oil pump drive gear so that large chamfered inner side faces rearward.
15. Install timing chain guides.

Fig. 12 Timing chain installation. Z24:

16. Set timing chain on camshaft and crankshaft sprockets aligning matching marks on chain with marks on sprockets, Fig. 12, and install camshaft sprocket with dowel pin in position marked during removal. Torque sprocket bolt to specification.

Fig. 7 Timing Chain Tensioner Installation:

17. Install timing chain tensioner assembly and adjust protrusion of tensioner to 0 inch, Fig. 13. After tensioner has been installed, check amount of timing chain stretch. If timing chain is excessively stretched, remove tensioner and timing chain, remove camshaft sprocket and advance it to the next dowel pin position. Repeat installation procedure outlined above. If dowel pin is already in position No. 3 of camshaft sprocket, replace timing chain and tensioner assembly.
18. Install oil seal in front cover using seal driver, then place front cover gaskets on engine and apply sealer to coolant passages.
19. Install front cover making sure that correct length bolts are used.
20. Apply lithium grease to front seal lip.
21. Torque front cover bolts to specifications.
22. Install crankshaft pulley and torque bolt to specifications.

Fig. 14 Cylinder head bolt tightening sequence:

23. Torque head bolts to specifications in sequence, Fig. 14.
24. Adjust valve clearance to specifications.
25. Install valve rocker cover.
26. Install oil strainer, then install oil pan.
27. Install oil pump and distributor driving spindle in front cover.

Fig. 15 Intake manifold installation:

28. Partially thread intake manifold bolts and nut with washers into lower and center positions on cylinder head, Fig. 15.
29. Install intake manifold and related components in reverse order of removal.
30. With No. 1 piston T.D.C. of the compression stroke, install distributor.
31. Install remaining components in reverse order of removal and install assembly in vehicle.
32. Fill engine oil and coolant to specified levels and make necessary adjustments