It’s gotta be done
It’s about that time when Toyota recommends the replacement of spark plugs, typically when your vehicle reaches 120,000 miles. There are some benefits, but it’s safe to say this falls within routine maintenance and can be very costly. The dealer I talked with had proposed $900 for the job, which seemed unreasonable for a set of cheap spark plugs. Let’s look through the work that is required and you can make the decision for yourself.
Having done this before, this should serve as a helpful guide for those of you in the same predicament. There really isn’t any need to disassemble a large part of what’s under the hood. This guide will focus primarily in on getting the spark plugs replaced with the least amount of work required. Estimation is 2 to 4 hours, but will require a long reach and strong nimble fingers.
What Do I Need?
4 & 8 millimeter allen wrenches
10, 12 & 14 millimeter sockets (10 will be used most often)
Rubber spark plug socket (5/8 inches)
10 millimeter wrench
12 & 14 millimeter ratchet wrenches (makes things easier…)
Small ratchet with extensions
Flexible ratchet
Gloves
Standard and needle nose pliars
Optional…
Paper towels
Flat head screwdriver
Duster
Electric tape
Hat (…your hair will be brushing against the vehicle a lot)
Towel (…to cover parts that will be laid on)
First disconnect the battery
While wearing gloves use the 10 millimeter wrench to loosen the bolts on the battery. Carefully remove both sides and separate them from the battery, being extra careful not to touch both connections at the same time (otherwise you could get shocked). There should be a slight sizzle sound, which is okay.
Place a towel or make sure the area is safe for working later. There will be lots of time spent leaning over this area, so make sure it’s setup in a way that is safe.
First Set of Three Spark Plugs
The spark plugs are split into two sections, three in the front and three in the back. The front set can be replaced in about 15 minutes. Be prepared to set aside approximately two to four hours for the rear spark plugs.
Remove the cover
Grab the smaller allen wrench and unlock the 3 bolts on the front of the frame. Once you unlock them, it should be fairly quick. If you have trouble getting it to unlock, use pliars on the allen wrench.
Change the spark plug
First remove the bolt on the side, unclip the wiring, then gently pull the lengthy tube out of the hole.
The right tools
There is a 5/8th inch socket specifically designed for spark plugs. This socket has a rubber inside which allows gripping and gentle installation. Connect this to a ratchet with a long extension, along with the socket and unscrew the spark plug from the hole. Once it is pulled out, place the new spark plug in the socket and gently screw the new one in its place.
Replace the Other Two Front Spark Plugs
Proceed in repeating these steps and replace the remaining two front spark plugs. The method will be the same on the rear, but with less room and no detaching of the wire assembly should be necessary (as they made the cables long enough to pull the spark plug tube out without detaching the wiring).
Remove 1 of 3
Begin to detach 3 sections. The first and simplest is the cables above the exhaust manifold, just above the new spark plugs. It’s in the way and will need to be moved. Only 3 10 millimeter bolts, a cable and a few pipes need to be detached and moved. Disassemble so the piece can be moved over the front spark plugs, out of the way, but no need to take anything out of the hood.
Start on the manifold
Just to continue in this section, remove the 4 bolts that require a 8 millimeter allen wrench. No need to get any extravagent tools for this one. Once the bolt is unlocked, it can be removed by hand. Proceed in removing the 4 bolts, the 2 12 millimeter bolts on each side, then remove the metal framing. This piece will be taken out of the hood and set down for reassembly later. Unfortunately, this is only the beginning of getting that exhaust manifold off.
Remove 2 of 3, air filter unit
Proceed in removing just the tubes and bolts to pull out the air filter unit. It’s fairly simple, 2 small 10 millimeter bolts and several tubes disconnected. Pulling the large tube off the exhaust manifold on the right should take a little force, but can be easily reassembled later. Place this piece out of the hood next to the engine cover and exhaust manifold bracket taken out earlier. This is the last piece that will be pulled out completely.
Remove 3 of 3
The challenge with removing the exhaust manifold is that it is bolted on with 3 brackets in the back that you will need to get to. See the picture below, the first bracket is not at all flexible and has a 14 millimeter bolt. The other two are 12 millimeters and can be removed using special tools. The short 12 and 14 millimeter ratchet wrenches are perfect for squeezing in and getting those out with little or no room. A great deal of force is needed, so it might make sense to put on sleeves when reaching in the back.
Remove the manifold
Proceed in removing the manifold. There are two pipes connected to the aluminum part on the right, which will spit out a little antifreeze. Not much will come out, but be aware when removing those pipes. Attempt to pull out the big piece as one and disconnect any lines that are connected. Helpful tips are using tape to identify which pipe goes to which, but mine were fortunately color coded already. You may need to use needle nose pliars to gently remove the older pipes that are sealed.
Change the spark plugs! (Finally)
The method is the same, but this time the cables are longer (as previously mentioned) and the wiring doesn’t have to be disconnected. Unbolt the spark plug tubes and proceed in replacing the spark plugs. The flexible ratchet will be very helpful in this case. I found that separating the ratchet from the extension helped me fit it in, then I would re-attach when unscrewing the spark plug.
Reassemble
Now that the spark plugs are replaced, reassemble everything. Getting those 3 bolts back on may very well be as difficult as taking them off and took me about the same amount of time. Once those are back on, the rest should go fairly quickly.
IMPORTANT: Make sure that every pipe and wire connection is double checked, that every line is connected thoroughly and routing to the correct place. This is critically important and could mean serious damage to the vehicle if not correctly assembled.
Clean it
There is an option to clean the pieces as you reassemble. Might as well, as these pieces are vacant and easy to access.
Check Your Work
As with any service maintenance, start up the car and let it sit idle for a bit. Some may take it for a short drive to make sure the check engine light doesn’t come on (which would suggest a pipe or wire assembly was not put on the right place). After a bit, the car should be good and ready for use.
I did notice that the front spark plugs appeared to be under more stress than the rears (as shown), which does relate to popular opinion to just change the fronts periodically (certainly easier).
Hope this helps in your project. I wish you the best!