How to change rear spark plugs
Replacing the back "bank" of spark plugs will require that you remove the Intake Manifold/plenum. Some have got to them without it, but a little more worth and swival/extensions.
I replaced my 2005 Sienna rear plugs without removing the Manifold by removing the Windshield Wiper Housing (5 Minute job). It gave you 6 inches of room to get your fingers in there. Trying to remove the left rear without removing the wiper housing is near impossible.
These are the steps: 1 - Remove the wiper bolt and wiper. Then Pop out the plastic cover. It is just held by plastic "V" inserts. 2 - Unscrew the bolts in the metal bottom and pop out the bottom. All easy 5 minute job. 3- You can easily see the Plugs and the bolts to remove. there are few things with sharp edges. Use tape or something to cover them if you don't want to get cuts. 4 - Rest is simple plug removal. I tried to remove the left rear plug previously for hours without removing the wiper cover and could not do it. It took me less than 10 minutes with the wiper cover off.
I changed sparkplugs on my 03 sieanna same motor.i got left rear plug on passenger side out by removing hose from pcv , and got the other two out with a lil patients.i didn't have to remove nothing to get to plugs just that hose from pcv.i used a 1/4 ratchet and abot a 3inch extention,and a 3/8 to 1/4 adapter.that way way I could use a 3/8 drive sparkplug socket.i recommend getting a magnetic sparkplug socket fom autozone.that way you wont have to worry about that rubber brooment coming out.also use ngk or denso long life laser iridum plugs.my van has went from 308 miles per tank full to 370 per tank full in city.havent drove it on hwy yet.just remove plastic engine cover,scope it out and take your time.it took me 2hrs 30mins.
the 2003 is a different motor johnboy84. It is the 3.0 litre v6. Much easier to work on. 2004 they switched to the 3.3.
Mik00000, I have been trying for the last couple of hours, and I can't even get the bolts off to get at the spark plugs. I got the far left bolt off, but that's it. The socket got stuck to that bolt, but I managed to get the bolt off, and then throw the bolt + socket on the ground several times to get them apart. I probably should have stopped there, but then I attempted to get the bolt on the far right off. Now the socket is stuck on that. I grabbed another ratchet and socket and tried to see if I could just get it on the middle one, and I couldn't. So I called it quits for the night. Are there any special tools you used? I don't understand how you even got the bolts off, let alone the spark plugs out in that small of a space. Are you sure you have a 2005 Sienna? I mean, yours looks the same as mine... maybe it's a slightly different manufacture? I know that there are two different kinds of 2005 manufactures. I attached a picture of my van.
Here is the far left one. I have my finger over the bolt hole. There's barely any room to move around. And I have tiny hands (I'm a woman... my husband has big hands and so didn't even attempt).
And right here is the socket stuck on the bolt for the one on the far right.
And here is my hand trying to reach in to the one on the far right. My hand barely even fits in there, let alone trying to do anything in there.
No dice. So... that's as far out as I could get the left rear ignition coil/boot to change the spark plug. Looks like the whole intake manifold and everything needs to be taken out to change those rear 3 spark plugs. You must have a different manufacture date or something. It's impossible to get the coils/boots out. There's just not enough room. I tried turning it every which way, but there's too much stuff in the way. It's impossible.
I have a 03 Sienna and just did the spark plugs without removing the intake manifold It is a tight fit but can be done. You may have to turn and angle the ignition coils to get them in and out but I was able to do it without disconnecting anything other than the coil wires.
The design has simply changed. Check out this video of a 2002 Sienna: https://youtu.be/a5orM7uFVps There is simply wayyyyyyyyyy more room than I had to work with. I have tiny little woman hands. My index finger is smaller than my husband's pinky finger. And even I had trouble fitting my hands in there. When I finally got the bolt off to take the coil out, there simply wasn't enough headroom to get the coil out. It didn't matter which angle I would turn. There is not enough room. You just can't compare a 2003 with a 2005. They're just not the same.
Looking for a Used Sienna in your area?
CarGurus has 26,149 nationwide Sienna listings starting at $600.
Search Toyota Sienna Questions
Toyota Sienna Experts