One common maintenance item one should not neglect is the spark plugs. Nissan recommends that the spark plugs be changed every 30k miles. By changing the plugs regularly, this helps keep your truck in top tune and prevents wasted gas by allowing for proper fuel combustion.
Why should you change your plugs? If you bought your truck used (like I did), you dont know when they were changed last.. mabye never?. Here is the comparison between my old plugs (top) and new plugs (right).
See for yourself. This looks to be nearly 100,000 miles of wear on the old plugs. Both gas mileage and driveability were suffering when I finally decided I should take a look and replace them.
- Tools Needed:
- Nissan supplied spark plug tool kit
- 19mm open end wrench
- Air compressor and a blower nozzle attatchment
- Conductive Anti-seize compound
- Spark plug gap gauge/tool
- Parts Needed:
- Spark Plugs. Nissan Recommends: (6) NGK BKR6EY
Procedure:
1. Let the engine cool down completely. This procedure will be MUCH easier if done on a cold engine. I burned myself a couple times by being too hasty and not waiting for the engine to cool completely. Also, there is a greater chance of stripping the threads in the sparkplug hole if the engine is warm, so let it cool overnight before changing the plugs. Find the Nissan supplied spark plug tool kit. This should be with your vehicle in a small black bag. In my Pathfinder, this bag was found under one of the rear seats.
The tool kit contains a handle (top), a short spark plug socket (middle), and a long spark plug socket (bottom).
The handle has two ends, a bladed end which only works in the short socket, and a round end, which only works in the long socket. The socket ends contain a rubber oring which will grab and hold the spark plugs. This is important, as the wells for the spark plugs are inaccessable by hand or any other tools. Both of these sockets are needed for this procedure.
2. Starting on the left side bank (looking at the engine from the front of the truck), unplug the spark plug wires for only the left cylinder bank. They are usually pretty stubborn and may require a towel or rag in order to get a good grip on them. Leave the wires attatched to the distributor cap but lay the loose ends off to the side. If the wires are not numbered, it would be a good idea to number them now so as to prevent confusion. The wire numbers are (from the front of the engine) 1,3,5 for this side of the engine.
3. Once the plug wires have been removed from the plugs, use the air compressor to blow out the spark plug wells. This is very important, as dirt, grit, and gravel tends to settle in these areas. You do not want this stuff to get into the engine when you remove the old plugs, so take the time to clean it out properly.
4. Now, you must remove the cover for the ignition coil.
The cover gets in the way of the spark plug socket when you are removing the spark plugs for cylinders #3 and #5. To remove this, just grab it as shown in the picture (bwlow) and pull it towards you. It will simply slide off the coil and you can place it off to the side.
5. Using the short socket and the blade end of the handle, proceed to remove the spark plugs on the left bank of the engine.
If yours are anything like mine, they will be TIGHT. This is due to the dissimilar metals. The aluminum of the head and the steel of the spark plug cause corrosion to occur. This tends to cause the plugs to seize in place. So, go slowly. Inch them out little by little. It took me about an hour and a half to remove all 6 plugs because I was afraid of breaking the plug off in the head (this is VERY bad). If you have to, you could spray a little WD40 into the well and let it sit a while to help loosen the plugs (you will need to clean this up after you get the plug out if it has puddled to ensure a good conductive surface), but I was able to do it without any penetrating oil.
6. Now, grab your new plugs and the plug gapping tool. You'll want to make sure the gaps on the new plugs are around .034". Nissan specs call for .032"-.035", so anything inbetween is fine.
7. Once the plugs are gapped, use a little anti-seize on the threads of the sparkplugs just before you put each one in on the left bank (to avoid getting contaminants on the anti-seize). Use the short socket tool to thread the plugs in place (by hand first). Once you have them as tight as you can get by hand, carefully torque them in place with the handle for the socket. NGK specs call for 1/2-2/3 turn after hand tightening. This correspends to approximately 18-21 lb/ft of torque. You will ahve to judge this by hand with the Nissan tool unless you have a torque wrench, extension, and socket to do the job. Install and torque the new plugs for each cylinder on the left bank.
8. Now moving to the right bank, we have the intake manifold to work around. These first two spark plug wires are perhaps the most stubborn to remove by hand. I found that a 19mm open end wrench gives perfect leverage to simply raise the plug wires off the spark plugs. Just insert the open end of the wrench just under the ridge on the plug wire. Then just lever it upwards using the manifold as a pivot point. Works like a charm. You will see why these wires are stubborn when you pull them out.. the ends are VERY long. Remove the first two wires of the right bank in this manner. While you are at it, if these plug wires are not numbered, they should be numbered 2,4,6 (from the front of the engine) to correspond to the cylinder number.
9. Once the first two wires have been pulled out, go ahead and blow out the wells for these two plugs to make sure that no dust, dirt, or bits of gravel are sitting down there.
10. Now, using the long socket and the round end of the handle, proceed to remove the first two spark plugs on the right bank of the engine. They will probably also be tight. So, again, go slowly.
11. Now, go ahead and install the new plugs in their spots with the long socket for the first 2 plugs on the right bank. Rmember to use a dab of antiseize on the threads just before you put each one in place. Hand tighten each plug and then torque them using the handle and socket or a torque wrench, extension, and socket.
12. And now comes the fun plug. The one on the very far back right bank is the worst to get to. Using a rag, you will ahve to reach behind the head with your left hand (I did this while actually sitting on the radiator core support) and pull the plug wire out.
13. Once this plug wire is out, blow the spark plug well clean using compressed air.
14. Using the short socket and the blade end of the handle, proceed to remove this last spark plug on the right bank of the engine. This one will take quite a while to remove, as you will only be able to make 1/4 turn at a time before having to re-orient the handle for the socket. Take it slow and remove the plug.
15. Now, go ahead and install the last new plug in its spot with the short socket. Remember to use a dab of antiseize on the threads just before you put the plug in place. Hand tighten the plug and then torque using the handle and socket or a torque wrench, extension, and socket. One thing to take note of.. there is a vacuum line that runs right around the backside of this last plug. On my truck, it came unplugged from the intake manifold when I removed the plug wire. Make sure this vacuum line is in place and not disconnected.
16. Replace the ignition coil cover, and plug all spark plug wires back into their respective spots. When plugging in the wire, they will make a distinctive snap when they are in place.
And thats it! Congratulations, you are done! Now go and take it for a spin..