How to Adjust Valves for a 1995 Nissan Truckby Mark Abbott
As in any vehicle, the valve-train components in your Nissan truck are subject to wear over time. Their dimensions will change, at which point the vehicle will become subject to problems such as valve-train noise and reduced power. This condition will continue to progress, unless you plan to stay one step ahead, performing regular maintenance and a periodic valve adjustment when one is needed.
Run the engine to warm it thoroughly. Although valves can be adjusted cold, the manufacturer's specifications are for a hot engine and if they are adjusted cold, they will have to be rechecked hot and possibly readjusted.
Remove the air cleaner, spark plug wires and their supports from the rocker arm cover. Use a spark plug boot puller to remove the wires, so that they are not damaged.
Use a screwdriver to disconnect the brake booster vacuum hose and move it to the side for access.
Remove the bolts from the rocker arm cover, with a ratchet and socket. If the cover is stuck to the head, bump it with a wood block and a hammer to loosen it. Do not use a pry bar or you risk damaging the sealing surfaces of the head and cover, leading to future oil leaks.
Ensure that the parking brake is engaged and the transmission in neutral. Remove the coil wire from the center of the distributor cap and ground it to the engine block, using a jumper wire with alligator clips.
Note the position on the distributor cap and the No. 1 spark plug wire, and mark it on the distributor body. Remove the cap and set it aside.
Attach a large socket with a breaker bar to the bolt at the front of the crankshaft pulley and turn the crankshaft clockwise until the notch in the pulley lines up to the "0" mark on the timing plate. The objective is to bring the No. 1 piston to top dead center on the compression stroke.
Check the distributor rotor to ensure that it is pointing directly at the mark you made earlier on the distributor body. If is pointing to the No. 4 plug, it is on the exhaust stroke and you will have to keep turning one more full turn (360 degrees), until it comes back around on the compression stroke.
Check the rotor again to ensure you are on the proper stroke, and then you can proceed to check and adjust valve clearances for the 1, 2, 4 and 6 valves.
Insert a 0.012 inch (0.30 millimeter) feeler gauge between the adjuster screw and the valve stem. If the gauge fits with a slight drag, there is no adjustment necessary. If adjustment is necessary, loosen the screw's lock nut and adjust the screw as necessary, and then re-secure the lock nut. Recheck the clearance afterward to ensure that it did not change and repeat this procedure for each of the 1, 2, 4 and 6 valves.
Turn the crankshaft nut one more complete revolution to bring the No. 4 piston to top dead center on the compression stroke. From this position, you can adjust the 3, 5, 7 and 8 valves in the same manner as the other four.
Use a gasket scraper to remove the old gasket material from the head and rocker cover sealing surfaces, cleaning them thoroughly. Apply a continuous bead of sealant to the mating surface of the rocker cover, taking care to apply it also to the inside of the mounting bolt holes.
Place the new rocker cover gasket on top of the head, lining up all the holes, and install the rocker cover on top of it. Install the mounting bolts securely, while the sealant is still wet.
Reinstall the rest of the components removed, beginning with the distributor cap and spark plugs and ending with the air cleaner.
- "Nissan Pick-Ups Automotive Repair Manual"; Rik Paul, et al.; 1995
- Earlycuda.org: Valve Adjustments, How and Why
- When disconnecting spark plug wires, tag them with the numbers of their respective cylinders and mark the cap as well to ensure that they are properly reconnected.
Things You'll Need
- Spark plug boot puller
- Screwdriver set
- Socket set
- Jumper wire with alligator clips
- Breaker bar
- Block of wood
- Feeler gauge set
- Gasket scraper
- Silicone sealant
- Remember that components inside your engine may be hot to the touch. Be sure to use cloth gloves and rags to handle hot parts and always wear safety glasses.
Mark Abbott began his professional writing career in 2011. He earned his Associate of Occupational Studies degree in automotive technology in 1997 from Western Technical College in El Paso. Abbott also holds a certificate of completion as a professional truck driver from Mesilla Valley Training Institute in Canutillo, Texas.