[camfaj]

Thanks so much for putting this together. I know that it must have taken considerable time and effort on your part. Very concise and informative. I used it to guide me through spark plug changeout in a 2004 Sienna and it saved me tons of time and heartache. Thanks again...camfaj

 

[namantm]

Here are a couple observations to make it easier to remove the back three spark plugs. I have just completed spark plugs changeout on my 2004 Sienna XLE with 152,000 miles.

As mentioned in many of the excellent threads already, there are three bolts that need to be removed from the back of the intake manifold to complete the back three spark plugs changeout. The first one on the passenger side is 14mm. The other two on the driver side are 12 mm, and they are easily accessible once the throttle body is removed.

In order to remove the 14mm bolt, there is a 10mm nut that holds the tubing behind the bolt that needs to be removed to access the 14mm bolt. With a 10 mm wrench, it can be accomplished. You can then push the tubing out of the way to have access to the 14mm bolt.

Now here is a tip for you. Raise the Sienna with a floor jack, and support it by a jack stand. There is a lower 14mm bolt that holds the bracket to the engine. Remove it with a 6 inch extension and now you can move the intake manifold around to make access to the passenger side 14mm bolt easier.

Remove the four intake manifold bolts and two nuts, and use a ratchet wrench to remove the 14mm bolt. Reverse the procedure for installation.

 

[tkkbkmweb]

Thanks so much for this document! It was a great help. Adding a coil clip replacement document that I created. Lots of people seem to have this issue. I had it on two of my six coil clips. Coil clip housing part number 90380-11885

 

[Highpockets57]

Wow, I wish I had known about this BEFORE I changed my plugs! I did it WITHOUT removing the plenum. Of course I was working blind on most of it and the passenger side plug was the worst. I guess it helps that I have been and aircraft mechanic for upwards of 30 years and it's not the first time I had to work blind. Thanks for the write up!
Highpockets

 

[cprimero]

you would think with the 1mz motors they would think to make them easier. Agreed on who ever said that toyota should give out certifications for this.

 

[tingsao]

Thank you for the write-up and documentation!

FWIW, I dropped the 14MM bolt on the back. I guess it will fall out on the road somewhere. I don't plan on replacing it. That plenum isn't going to go anywhere without it.

Also, I wish I had read your guide before starting. I didn't change the gasket, because I'm too far from the dealer, and I already had the wiper cowl off, and half the air intake. The wife and kids were at a birthday party, so the other car was gone.

In retrospect, this didn't have to be a super tough job. Reassembly was a breeze. Here are a few tool recommendations:


1.) Ratcheting box-end 12MM wrench for a few of the 12mm bolts, particularly the 12MM at the rear of the plenum. (I had a 7/16 that worked. I plan on getting a metric set. Father's day is coming!)
2.) Masking tape and a pen - to label all of the vacuum hoses. Not really necessary, but the white/yellow tape contrasts against the black, and makes sure you notice the missing hoses.
3.) Cordless impact driver with 1/4" and 3/8" adapters, a 6" - 8" socket extension and one "elbow" or swivel.

The impact driver made short work of everything once I decided to break it out, especially taking down the wiper cowl. Fast, fast.

Some observations:

• No, don't even think about skipping a step in this guide. You WILL have to take off the wiper cowl, and you WILL have to remove the plenum.
• When removing the wiper cowl, a rocker arm was in the way of a 10mm bolt. I could have used a box-end wrench, but that would have been a pain, so I turned on the key and let the wipers do a half cycle then turned off the key. (Since the wipers are already off at this point, just guess. You'll probably be right, and if not, try again.) This allowed me to get right at that bolt with the impact driver.
• I tested the engine before I reinstalled the cowl, so while I was doing that, I cycled the wipers a full cycle one more time.
• Also, you will have to take the air intake manifold apart in two stages, as the guide directs, because you won't be able to remove the bolts otherwise.
• Don't forget to put the clamp back on the vacuum hose for the brake booster. Mine already had the clamp out of place. Someone in the past forgot it while doing some kind of work. Probably the dealer, because the guy I bought the van from gave me a book full of maintenance records, all dealer. Surprised my brakes still worked well.

Thanks again!

 

[josephg]

Very good guide Darren. I just replaced the spark plugs on my wife's 2006. One hint for those that decide to replace the plenum gasket, which BTW is a good idea as the old one came out pretty compressed, during the reinstallation, before tackling the rear plenum bolts install and torque all the front bolts holding the plenum to the intake manifold in order to compress the new gasket. Otherwise the bracket holes will not line up with the the plenum captive nuts making the installation difficult.

Joe

 

[tonystewart]

dhayes5....Thank you for the excellent guide

 

[solar]

Thank you Darren for your pdf tutorial, made my spark plug changing afternoon much smoother, specially those hidden bolts.
BTW guys (and girls?) The one on the left is really hard to remove with the metal tubing aligned... you have to force it a little (or a little more...)

Gaskets were in good shape but I am waiting for new ones from the dealership. Here in Canada they cost 21.95 for air manifold gasket and 14.95 for the quad looking plenum gasket. With all that work it is worth it IMHO.
Had an issue with the front middle plug, boot had melted on it, I had to destroy the boot with the tip of a long sawzall blade in order to unscrew the plug. Plug was burnt on the ceramic part! I guess this is why we change plugs every 12 years.
Dealership does not sell boots on their own, just coil pack: $145. I will try no boot for a while, till I get to Florida (RockAuto sells boot for $4). Don't even see how it is useful, I highly doubt spark is going to jump sideways.
Thanks again
Seb

 

[spk]

Thanks Sienna forums and all the contributors to this thread. Finished the job today under 5hrs - worst part was that 14mm bolt in the back - didn't bother to put it back.

Pro tips:
- Take your time
- try to replace the intake gasket - cheap insurance
- wipe down all gasket mating surfaces with a cleaner (brake cleaner works)
- If you can do a brake job, you can do this.
- STRETCH before - your hamstrings/legs will get tight.
- Drink water - I was in the zone and forgot to drink water, legs started to cramp.

 

[jojy_sv]

Your post has been excellent. I have a been able to replace the spark plugs.
I have made a mistake. I dropped the 14mm bolt at the rear end of the plenum . Does any one know the toyota part number for the same.

I spend around 4.5 hour to do the replacement.

Thanks a lot for the help

 

[livesnearcostco]

Thanks everyone for the tips. I just did this Sunday at 190,000 miles and it took me several hours but now I could probably do it in less than 3 hours. My observations...

• Removing the windshield wipers, motor, cowl and tray is fairly easy, just time consuming. I've done it twice now!
• Don't disconnect coolant line from throttle body, just move it aside; I disconnected it briefly and it leaked some coolant.
• I disconnected air control valve from TB then TB from plenum, making it easy to get the rightmost two rear bolts off
• Broke clips on all 6 coil plugs, resecured them to coils with zip ties
• Changed PCV valve

Removed 14mm left rear bolt with regular box wrench, very difficult. Couldn't put it back, so wedged it in place without tightening it, then forgot about it and reassembled everything else. A few days later I removed the wipes, wiper motor and cowell again to try to tighten it and the bolt fell out onto the ground. The darn hose behind it was preventing me from starting the bolt threads. I went under the van and disconnected the bottom 10mm nut holding the bottom of the hose bracket but that didn't help. Then I loosened--but did not remove--the upper 10mm nut holding the hose to the bracket. That let me push the hose slightly away and insert the 14mm bolt and tighten it. Then I tightened the top 10mm nut and reinstalled the bottom 10mm nut.

I have 10mm, 12mm and 14mm ratcheting box wrenches and those helped with the bolts/nuts behind the intake manifold. I did not try removing the bolt/nut holding the bottom of the right (passenger) side manifold bracket. That might have worked too, as suggested earlier in this thread. But I think loosening the 10mm nut holding the hose behind the manifold is the best option, though you have to do it by feel.

 

[cmoore]

I just did this job yesterday at 157,890 miles. I'm glad to say the factory plugs that I took out of our 2004 LE looked exceptionally good. The van was running good so I wasn't really surprised but still that's longer than I've ever run a set of plugs. The step by step posted in this thread was excellent so thank you for posting it up. The 14 mm bolt on the left rear gave me fits. I was finally able to get it loose by taking out those 10 mm bolts holding the tubing in place. I guess that gave me just enough room to get it out and back in. The tabs on the coil sticks broke so I rigged up a harness with zip ties to keep things in place. Thanks again. Now it's on to that whiney power steering pump.

 

[Skeet33]

...My only suggestion would be to remove the front wheels and rotors. Then, drop the front end so the bumper is touching the ground. This makes it easier to reach the backside of the engine without climbing on top of it.

Fantastic hack - - Thank You!! Having both feet on the ground made all the work on the rear bank so much less of a strain.

I found removing the rotors would help very little, since the lower ball joint was at almost the same elevation. Instead, I jacked it from the center jacking point, removed the front wheels, then set it down onto a 4x4 laid down under each control arm. This compressed the suspension and left the rotors about an inch from the ground.

This was a long, arduous job for me. I did spark plugs, PCV, valve cover gaskets, and intake plenum gasket. All of them WAY overdue at 245,000 miles!
I was astounded at how perfect the plugs looked after nearly a quarter of a million miles. The coil clips will definitely break, so try to pull the coil packs without disconnecting. I was able to do this on all 3 rear plugs, and might have been able to on the fronts if I'd thought to loosen the wiring harness first.

The valve cover gaskets had turned to hard plastic and I was leaking oil pretty badly. I should have done this job long ago. One huge comfort is how much I saved by DIYing it. Get an estimate on plugs and intake gaskets from a mechanic or two and you'll be motivated to take this job on!

 

[paul r]

If I am not mistaken , the head of the problematic 14mm bolt is recessed within the "U" of the bracket making it difficult to use a wrench to remove and install it properly. The next time I do this job I will find a longer bolt and space it out with washers . I had difficulty reinstalling it initially as the holes would not line up, so I went under the van and loosened the nut/bolt , cannot remember which, securing the bracket and this allowed the bracket to wiggle a bit so the bolt hole could line up.