REMOVAL & INSTALLATION
Z24i and KA24E Engines
See Figures 1 and 2
Removal of the cylinder head from the engine is optional. Mark and keep all parts in order for correct installation.
- Disconnect the negative battery cable.
- Either remove the cylinder head from the vehicle, or if the job is to be attempted with the cylinder head installed, remove the necessary components for access to the camshaft. Begin by removing the cylinder head cover.
- Set the No. 1 piston at TDC on its compression stroke, then remove the camshaft sprocket from the camshaft together with the timing chain.
The KA24E engine is unique in that its hydraulic lifters are installed inside the rocker arm assemblies. If a hydraulic lifter is kept on its side, even when installed in the rocker arm assembly, there is the possibility of air entering it. After removal, always set rocker arm assembly straight up.
- Loosen the bolts holding the rocker shaft assembly in place, then remove the six center bolts. Do not pull the four end bolts out of the rocker assembly because they hold the unit together.
When loosening the bolts, work from the ends inward and loosen all of the bolts a little at a time, so that you do not strain the camshaft or the rocker assembly. Remember, the camshaft is under pressure from the valve springs.
- After removing the rocker assembly, remove the camshaft. Slide the camshaft carefully out of the front of the vehicle.
Mark and keep the disassembled parts in order.
If you disassembled the rocker unit, assemble as follows:
Position the mounting brackets, valve rockers and springs, observing the following considerations:
- The two rocker shafts are different. Both have punch marks in the ends that face the front of the engine. The rocker shaft that goes on the side of the intake manifold has two slits in its end just below the punch mark. The exhaust side rocker shaft does not have slits.
- The rocker arms for the intake and exhaust valves are interchangeable between cylinders one and three and are identified by the mark 1 . Similarly, the rockers for cylinders two and four are interchangeable and are identified by the mark 2 .
- The rocker shaft mounting brackets are also coded for correct placement with either an A or a Z plus a number code.
- Check camshaft run-out, end-play, wear, and journal clearance.
- Apply sealant to the end camshaft saddles, as shown in the accompanying illustration. Place the camshaft on the head with its knockpin pointing up.
- Fit the rocker assembly on the head, making sure you mount it on its knock pin.
- Tighten the bolts to 11-18 ft. lbs. (15-25 Nm) on the Z24i engine or to 27-30 ft. lbs. (37-41 Nm) on the KA24E engine, in several stages working from the middle bolts and moving outwards on both sides.
Make sure that the engine is at TDC of the compression stroke for the No. 1 piston or you may damage some valves.
- On the Z24i engine, check and adjust the valves, as necessary.
- If removed, install the cylinder head.
- Install the cylinder head cover.
See Figures 3 and 4
Nissan recommends that the cylinder heads be removed from the engine, if the engine is mounted in the vehicle, before removing the camshafts.
- Disconnect the negative battery cable.
- Remove the timing belt.
- Remove the cylinder head.
- With cylinder head mounted on a suitable workbench, remove the rocker shafts with rocker arms. Bolts should be loosened in two or three stages.
Hold the valve lifters with wire so that they will not drop from the lifter guide. Put an identification mark on the lifters or guide to avoid mixing them up.
- At the rear of the cylinder head, remove the cylinder head rear cover, the camshaft bolt and the locating plate.
- Remove the camshaft front oil seal and then slide the camshaft out the front of the cylinder head assembly.
- Install the camshaft, locator plate, cylinder head rear cover and front oil seal. Set the camshaft knock pin at the 12:00 o'clock position (straight up).
- Install cylinder head with new gasket to engine.
- Install valve lifter guide assembly, being sure that the valve lifters are retained in their original positions. After installing them in the correct location, remove the wire holding them in lifter guide.
Install the rocker shafts in position with their rocker arms. Tighten the bolts in two or three stages to 13-16 ft. lbs. (18-22 Nm). Before tightening, be sure to set the camshaft lobe in a position where the lobe is not lifted or the valve closed. You can set each cylinder one at a time or follow the procedure below (the timing belt must be installed in the correct position):
- Set the No. 1 piston at TDC of its compression stroke, then tighten the rocker shaft bolts for the No. 2, No. 4 and No. 6 cylinders.
- Set the No. 4 piston at TDC of its compression stroke, then tighten the rocker shaft bolts for the No. 1, No. 3 and No. 5 cylinders.
- Tighten the rocker shaft retaining bolts to 13-16 ft. lbs. (18-22 Nm).
- Install the rear timing belt cover and camshaft sprocket. The left and right camshaft sprockets are different parts. Install the correct sprocket in the correct position.
The right and left camshaft sprockets are different parts. Install them in their correct positions. The right sprocket has an R3 identification mark and the left has an L3.
- Install the timing belt.
- Connect the negative battery cable.
CHECKING CAMSHAFT RUN-OUT
See Figure 5
Camshaft run-out should be checked when the camshaft has been removed from the engine. An accurate dial indicator is needed for this procedure; engine specialists and most machine shops have this equipment. If you have access to a dial indicator, or can take your camshaft to someone who does, measure the camshaft bearing journal run-out. The maximum (limit) run-out on the Z24i camshafts is 0.0008 in. (0.2mm). The run-out limit on the KA24E camshafts is 0.0047 in. (0.12mm). The maximum (limit) run-out on the VG30i and VG30E camshaft is 0.0039 in. (0.1mm) If the run-out exceeds the service limit, it should be replaced.
CHECKING CAMSHAFT LOBE HEIGHT
See Figure 6
Use a micrometer to check camshaft lobe height, making sure the anvil and the spindle of the micrometer are positioned directly on the heel and tip of the camshaft lobe.
CHECKING CAMSHAFT JOURNALS & BEARINGS
See Figures 7 and 8
While the camshaft is still removed from the cylinder head, the camshaft bearing journals should be measured with a micrometer. Compare the measurements with those listed in the Camshaft Specifications chart. If the measurements are less than the limits listed in the chart, the camshaft will require replacement, since the camshafts in all of the engines covered in this manual run directly on the cylinder head surface; no actual bearings or bushings are used, so no oversize bearings or bushings are available.
Using an inside dial gauge or inside micrometer, measure the inside diameter of the camshaft saddles. The camshaft journal oil clearances are listed in the Camshaft Specifications chart. If the saddle inside diameters are worn, the cylinder head must be replaced (again, because oversize bearings or bushings are not available).
CHECKING CAMSHAFT END-PLAY
See Figures 9 and 10
After the camshaft has been installed, end-play should be checked. Use a dial gauge to check the end-play, by moving the camshaft forward and backward in the cylinder head. End-play specifications should be as noted in the Camshaft Specifications chart.