Valve adjustment determines how far the valves enter the cylinder and how long they stay open and closed.
If the valve clearance is too large, part of the lift of the camshaft will be used in removing the excessive clearance. Consequently, the valve will not be opening as far as it should. This condition has 2 effects:
If the valve clearance is too small, the valves will open too far and not fully seat in the cylinder head when they close. When a valve seats itself in the cylinder head, it does 2 things:
If the valve clearance is too small, the engine will run poorly because of the gases escaping from the combustion chamber. The valves will also become overheated and warped, since they cannot transfer heat unless they are touching the valve seat in the cylinder head.
While all valve adjustments must be made as accurately as possible, it is better to have the valve adjustment slightly loose than slightly tight, as a burned valve may result from overly tight adjustments.
EXCEPT CD17 AND GA16DE ENGINES
See Figures 1, 2 and 3
The GA16i, CA16DE, CA18DE and SR20DE engines use hydraulic lifters. No valve adjustment is necessary or possible. Nissan recommends that valve adjustment on all other models be done every 12 months or 15,000 miles (24,000 km).
- Run the engine until it reaches normal operating temperature. Oil temperature, not water temperature, is critical to valve adjustment. With this in mind, make sure the engine is fully warmed up since this is the only way to make sure the parts have reached their full expansion. Generally speaking, this takes around 15 minutes. After the engine has reached normal operating temperature, shut it off.
- Purchase a new valve cover gasket before removing the valve cover. The new silicone gasket sealers are just as good or better if you can't find a gasket.
- Note the location of any hoses or wires which may interfere with valve cover removal, disconnect and move them aside. Remove the bolts which hold the valve cover in place.
- After the valve cover has been removed, the next step is to get the number one piston at TDC on the compression stroke. There are at least two ways to do this: Bump the engine over with the starter or "turn it over'' by using a wrench on the front crankshaft pulley bolt. The easiest way to find TDC is to turn the engine slowly with a wrench (after first removing No. 1 plug) until the piston is at the top of its stroke and the TDC timing mark on the crankshaft pulley is in alignment with the timing mark pointer. At this point, the valves for No. 1 cylinder should be closed.
Make sure both valves are closed with the valve springs up as high as they will go. An easy way to find the compression stroke is to remove the distributor cap and observe which spark plug lead the rotor is pointing to. If the rotor points to No. 1 spark plug lead, No. 1 cylinder is on its compression stroke. When the rotor points to the No. 2 spark plug lead, No. 2 cylinder is on its compression stroke.
- Set the No. 1 piston at TDC of the compression stroke, then check and/or adjust the valve clearance Nos. 1, 2, 3 and 6.
- To adjust the clearance, loosen the locknut with a wrench and turn the adjuster with a screwdriver while holding the locknut. The correct size feeler gauge should pass with a slight drag between the rocker arm and the valve stem.
- Turn the crankshaft one full revolution to position the No. 4 piston at TDC of the compression stroke. Check and/or adjust the valves (counting from the front to the rear) Nos. 4, 5, 7 and 8.
- Replace the valve cover and torque the bolts on the valve cover down evenly.
See Figures 4, 5, 6, 7, 8 and 9
- Warm up the engine to normal operating temperature, then turn it OFF . Disconnect the negative battery cable.
- Remove the valve cover and spark plugs.
- Set No. 1 cylinder to TDC of the compression stroke. Align the pointer with the TDC mark on the crankshaft pulley. Check that the valve lifters on No. 1 cylinder are loose and lifters for No. 4 cylinder are tight.
- Check the valve clearance for intake valves of No. 1 and 2 cylinders. Check the clearance for exhaust valves of No. 1 and 3 cylinders.
Use a feeler gauge to measure the clearances:
Intake valves (hot): 0.009-0.019 in. (0.23-0.48mm)
- Turn the crankshaft one revolution and align the TDC mark.
- Check the valve clearance for intake valves of No. 3 and 4 cylinders. Check the clearance for exhaust valves of No. 2 and 4 cylinders.
- To adjust the valves, turn the crankshaft so the camshaft lobe is in the upward position.
- Place tool KVC10115110 or equivalent, under the camshaft. Rotate the tool so that the valve lifter is pushed down.
- Place tool KV1011520 or equivalent, between the camshaft and the edge of the lifter. Remove tool KV10115110.
- Remove the adjusting shim using a small prybar and a magnet.
Determine the replacement shim size using the following formula:
- R = thickness of removed shim.
- N = thickness of new shim.
- M = measured valve clearance.
- Intake valve N = R + (M - 0.0146 in. (0.37mm)
- Exhaust valve N = R + (M - 0.0157 in. (0.40mm)
- Shims are available in 50 sizes from 0.0787 in. (2.00mm) to 0.1173 in. (2.98mm).
- Select a new shim with the thickness as close as possible to the calculated value.
- Install the new shim using the tool.
- Recheck all clearances after the new shims have been installed.
- Install a new valve cover gasket and valve cover.
- Install the remaining components, start the engine and check operation.
- If the engine has an unusually rough idle, the valve clearance may be too tight. If this is the case, readjust the valve clearance before internal engine damage.
CD17 (DIESEL) ENGINE
See Figures 10, 11 and 12
- Run the engine to normal operating temperature.
- Shut off the engine and remove the valve cover.
- Turn the crankshaft until #1 piston is at TDC of the compression stroke.
The following valves may now be adjusted:
#1 intake and exhaust
Measure the clearance between the cam lobe and the lifter. Valve clearance should be adjusted one valve at a time. Adjustment is made by removing or adding shims in the lifter. The shims are removed or added, not at TDC, with the nut
turn PAST TDC, in the normal direction of the rotation. A special tool, Nissan #KV11102600 is used. The tool should be inserted from the injector nozzle side of the head. The lifter has a cutout portion to aid in removing the shim. Turn the lifter so that this cutout is on the nozzle side. The shim should be stamped with their size, in millimeters. If, when you measure the clearance, you find that an adjustment is needed, remove the shim, note what size it is and determine what size you need to correct the gap.
Intake: 0.008-0.012 in. (0.20-0.30mm)
Turn the crankshaft until #4 piston is at TDC compression. The following valves may now be adjusted: