Good information. Was going to try today, but did not have enough time. Were you able to use a torque wrench to tighten the spark plugs on the back half of the engine?

 

Can it be done easier from the bottom ?

 

Never mind ! After seeing a tutorial on YouTube I now know that this was a piss-poor design by Toyota ! They did everything they could to ensure that 95% of buyers would have to take it back to the stealership for this routine maintenance

 

Thanks for the write up.
I did the spark plugs on my 08 Sienna, 3.5L. Toyota should offer a certificate of achievement or something for anyone who does this themselves.
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.

 

...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!

 

Ok, I have to ask... What did you use to support the van when lowering it to the bumper???

 

So I bought my plugs, gasket, and PCV valve today. Picked them up from the stealership on the way home from work. My son has a soccer game tomorrow at 10am, so I'm thinking I should be able to get this started by 1pm at the latest. If all goes well I hope to be done before dinner. BTW, I also found this video that I think will be incredibly helpful. It is for a Lexus ES330, but it's the same VVT-I 3.3L V6, 3MZ-FE engine. The only extra steps is looks like we (Sienna owners) need is to remove the wiper assembly, motor, shroud, etc... I'll check back in before I get started so if you want any specific pics just let me know.

 

Thanks for the guide. Good job. Did you have to remove the throttle body from the plenum?

Good video. I was wondering if you could get to the back plugs from the bottom, say, with a lift. Doesn't look like it since you have to pull out the coils.

 

Ok, I have to ask... What did you use to support the van when lowering it to the bumper???

I just used a floor jack (at the central jacking point), and rotated it 90 degrees after the van was lowered so I wouldn't be tripping over it. The bumper wasn't actually touching the ground. I didn't feel the need for jack stands since I wasn't going under the vehicle. Paranoid people could put a 6"X 6" piece of lumber at the jack points, just behind the front wheels.

 

HC, got it. That makes sense.

Time got away from me so I didn't get to do the plugs today. First thing tomorrow morning...

bmwpower, all the research I did on this did not turn up one person changing them from below. As for the TB, in the video above he left it connected to the intake plenum. That's what I plan to do tomorrow morning. Should save the extra work and the extra gasket to replace.

 

I can assure you that it is impossible to do this from below, unless you drop the subframe and engine. Good luck with the project, it takes lots of patience and a good set of tools. Expect to spend about 4 hours nonstop to change the plugs.

 

Ok, so I completed my spark plug change this weekend and thought I'd add some observations.

1. It took me about 4.5 hours to complete the job. I am not one to rush things and I like to clean/wipe down parts, and tools, as I go along.
2. In my humble opinion it is impossible to do this job without removing the wipers, wiper motor, and cowl. Doing so, you can actually see the two bolts behind the throttle body and that makes a world of difference when you need to get them off/on.
3. While you have all this apart go ahead and replace the intake manifold gasket and the PCV valve.
4. DO NOT disconnect the wires from the coil pack for the three rear plugs. There is plenty of room to pull them out, wires attached. See next entry...
5. As careful as I was I still managed to break all three tabs on the front three coil packs. plastic gets brittle with all that heat after 153K miles. Once I was done replacing the plugs I used tie wraps to hold the connectors in place. I have a note to check them at each oil change interval now.

I also cleaned the throttle body and did a 5 quart PMF on the tranny. I haven't driven much since yesterday but I can honestly say that the car runs and shifts smoother, so far.

 

I've got a 2005 with 119,500 miles. I'm still getting about 24-25 mpg at 70-75mph on trips. Do you think I need to change my plugs yet? I'm only planning on keeping it another year; say another 12k-15k miles.

 

dhayes5,

Could you tell me how were you able to remove the 10mm bolt/nut that holds the tubing behind the bracket?
The bolt next to the difficult 14mm bolt?

Thank you for your help.

 

Excellent post and DIY.

 

To anyone who has completed this job, you deserve a standing ovation. I can not believe that our auto makers have made vehicles impossible to work on. I am a senior citizen (71) and can remember the days of the 50's & 60's when you could replace all eight plugs in about 30 minutes. Almost anything you had to do under the hood, or underneath for that matter, you had all kind of room to work and most jobs were a "piece of cake" for DIY'ERS. Of course, then we had hand crank windows and air-conditioning was for the rich and famous. Congrats to all who have done this.

 

Hey Mike,

I may get scolded here, and it would be well deserved, but I'm at 137k on my '05 with original plugs. I've been meaning to get at it since 120k, and still have it high on my list to do before the snow flies. That said, the van runs as new. I'm keeping mine long haul but if I were you, no way would I brutalize my knuckles!

Mike..

 

Thank you very much dhyes5!
I did my plugs and valve cover gasket. Great write up!

Michael

 

Great info thanks wish I had read this when I did mine.


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Great write up and instructions. This helped me change my plugs. I also cleaned throttle body and changed PCV valve. The instructions provided made this a DIY job. Thank you for taking the time to put these instruction together.

 

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

 

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.

 

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

 

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

 

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.

 

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!