How to replace spark plugs on 2004 Nissan Quest?

Answer 1

The good: Only three tool sizes need

The bad: 7 hours and several band aids

I do like our Quest but not sure what they were thinking when they crammed in the engine with no way to easily change the plugs. I have worked on cars my entire life, rebuilt engines, replaced clutches and think of myself as fairly competent. This job humbled me.

With these instructions, plan on 4 hours.

Big picture. We will remove the intake manifold. It has three silver pieces:

1) the lowest part that feeds directly into the valves. We will leave that there.

2) the middle piece which is the part you see most of. We will completely remove that.

3) the back piece that connects the middle to the throttle. We will loosen that but leave it in place.

All directions (right and left) will be while looking toward the back of the car ... so the driver would now sit on the right side for example.

First, start on the right (looking toward the back of the car) and remove all the black rubber air intake pipes (large pipes).

Next remove all the misc vacuum items from the intake manifold. Should be three or four. Most taking a 10mm socket.

Now with the vacuum stuff out of the way, take out all the 12mm bolts (three) toward the front of the engine holding down the manifold and the two nuts on either side.

Now disconnect the EGR pipe (right side of the manifold. You need to remove the top two bolts and looses the two nuts at the bottom of the pipe because you need to slide it out of the way later.

Now remove the throttle body by taking out the four hex bolts.

Now way to the back part of the engine compartment to get off two 12mm bolts that hold the rear manifold piece in. Back lower part of the rear manifold and are connected to a bracket.

Now a tricky part. Nissan thought it would be a good idea to put a couple wiring harness on the back of the middle manifold. The easiest way is to slide the plastic connectors off the metal brackets. you can't see them but put s screwdriver into the metal bracket back to disengage the plastic lock and slide the connectors upward and off. The plastic locks face towards the drivers side (your right as you work on it) so bring your screwdriver in from that side.

Now the hard part. There are four bolts connecting the middle manifold to the back. Of course you can't see them and the bottom two are near impossible to get to. For the bottom two, I used a 12mm open ended wrench put a piece of rope around the end and had my son pull while I pushed. It may help to lift the manifold up to get the bottom two, while the top two are easily reached when the manifold is down.

Now you should be able to pull the whole middle manifold out. Be sure to cover up the manifold holes to make sure nothing drops down inside.

Replace the spark plugs and reverse the instructions.

Good Luck.

If you are mechanically inclined and previous mechanic that can visualize what you are working on. This can be done under 3 hours.

To make just a little more room to work, I removed the battery. Be sure when you take the vacuum lines off, you know where they go back on. Tape / label them.

I would suggest when you remove a bolt or nut, put it back into the hole so you remember where you got them from, just 4 or 5 threads will do.