Mazdax605
Mazdax605 UberDork
4/9/20 2:17 p.m.

Hey guys,

 

  On my 06 Sienna I'm around 186.5K miles, and the plugs were done around 85K miles several years ago. I originally bought the plugs from the dealer, and planned to do them myself all those years ago. Then I realized one cannot even see the rear plugs, so I paid the dealer to do it.  Now it's all these years later, and I don't really want to pay the dealer, or anyone for that matter to change them again. Maybe that's dumb of me. I watched a few YouTube videos on the spark plug replacement, and while it certainly doesn't look crazy difficult it also doesn't look easy.  Best to pay someone like I did before, ar try to tackle it myself? Anybody done this job before? Any tips if I decide to do it myself? Should I contemplate replacing the coils while I'm in there as they have 186k on them.

spitfirebill
spitfirebill MegaDork
4/9/20 2:24 p.m.

I need to do the plugs on our 2005 Sienna.   Were at 192k miles and I have no idea when they were done.  We bought it used.  I watched the YouTubes too.  I think the biggest help is to take the plenum for the wipers off.  It gives more room to get to the rear plugs.  

Mazdax605
Mazdax605 UberDork
4/9/20 5:18 p.m.
spitfirebill said:

I need to do the plugs on our 2005 Sienna.   Were at 192k miles and I have no idea when they were done.  We bought it used.  I watched the YouTubes too.  I think the biggest help is to take the plenum for the wipers off.  It gives more room to get to the rear plugs.  

Yeah I just saw that taking that part off really helps. Still not a pleasant job it seems. 

dj06482
dj06482 GRM+ Memberand UltraDork
4/9/20 6:11 p.m.

Our Rav4 has the 3.5L V6 and it wasn't too bad for a transverse V6. Worst part was having to remove the intake plenum and replace the gasket. I'm guessing things are a little bit tighter in the Sienna.

Mazdax605
Mazdax605 UberDork
4/9/20 6:25 p.m.
dj06482 said:

Our Rav4 has the 3.5L V6 and it wasn't too bad for a transverse V6. Worst part was having to remove the intake plenum and replace the gasket. I'm guessing things are a little bit tighter in the Sienna.

My Sienna has a 3.3 litre. It's sorta tucked under the cowl and looks pretty tough to get to the rear plugs. 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
4/9/20 6:58 p.m.

I worked with someone who could R&R the coils without removing the intake.

 

I am not that man.  I'll yank the upper plenum for access.

Mazdax605
Mazdax605 UberDork
4/9/20 7:04 p.m.
Pete. (l33t FS) said:

I worked with someone who could R&R the coils without removing the intake.

 

I am not that man.  I'll yank the upper plenum for access.

How, you can't even see them? 

TGMF
TGMF HalfDork
4/10/20 11:03 a.m.

you can do it without plenum removal . If you have long fingers/ thin hands+ forearms. If you've got  a muscular hand or forearm forget about it.  

Need a ratcheting 10mm wrench.  come in from the passenger side. unplug coil, remove 10mm bolt, use finger tips to pull coil up, cock sideways ish and fish out. now,  with a small extension  fish the plug socket and extension in. with another extension and a ratchet snap the extensions together while already in the spark plug tube.  break plug free with ratchet with the 10 degrees or so of  travel allowed, then as soon as able, remove ratchet and spin out by hand. once plug is loose, pull up to first extension connection and separate, allowing socket/ plug to fall back in hole. Now use a magnet to pull the  last extension and socket then the plug out. move on to the next, repeat.  get all plugs out then reassemble from drivers back to passenger side. It's all done by feel. each plug gets progressively harder to access.  it will chew up your forearm....but hey you're flat rate and time is money.  

Less pain and lots more time would pull the wipers, cowel, and intake.  Be known there's two bolts in the intake from the back side forward that are removed and installed by feel. They suck to get in straight.  easy to cross thread. 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
4/10/20 11:16 a.m.

In reply to TGMF :

I can tell if someone has been into one before by the fact that those two FU bolts are usually missing.

 

As far as seeing things... get eyes on your fingertips smiley

Mazdax605
Mazdax605 UberDork
4/10/20 11:35 a.m.
Pete. (l33t FS) said:

In reply to TGMF :

I can tell if someone has been into one before by the fact that those two FU bolts are usually missing.

 

As far as seeing things... get eyes on your fingertips smiley

Oh I have eyes on my fingertips, but my fingers are fat, like the rest of me. 

Mazdax605
Mazdax605 UberDork
4/30/20 8:54 p.m.

Okay I checked my records and the spark plugs were replaced in 2014 at 105k miles. They are recommended to be replaced every 120k. The van has 187k now, so I guess I have some time before they're due again.

1988RedT2
1988RedT2 MegaDork
4/30/20 9:05 p.m.

In reply to Mazdax605 :

On my MPV, one of the rear bank coils failed before the plugs were even due for a change.  I studied up on the Youtube and pulled the intake to get to it.  I did all three coils and plugs while I was in there.  Some of the front bank coils lasted to about 150k miles and I've replaced every single one.  Some cars are known for coils going bad.  The MPV is one of them.  I dunno about the Sienna, but that would probably influence my decision.  That and how long I was planning to keep the vehicle.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
5/2/20 6:15 a.m.

The spark plug interval is a MAX life, not a "due by".  120k means if you haven't had problems yet, change them already.

 

If you have a coil problem, change all the plugs, because the plugs caused the coil to fail.  Also change all the coils, or at least the three inaccesible ones under the plenum.

Mazdax605
Mazdax605 UberDork
5/2/20 6:18 a.m.
Pete. (l33t FS) said:

The spark plug interval is a MAX life, not a "due by".  120k means if you haven't had problems yet, change them already.

 

If you have a coil problem, change all the plugs, because the plugs caused the coil to fail.  Also change all the coils, or at least the three inaccesible ones under the plenum.

I'm not having any problems, just trying to get ahead of problems. Toyota suggests every 120k, we had the original set replaced at 105k. Now we're at 186k. Just wondering if I should do them sooner rather than later. Car runs great. A/C not working correctly right now though. 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
5/2/20 6:29 a.m.
Mazdax605 said:
Pete. (l33t FS) said:

The spark plug interval is a MAX life, not a "due by".  120k means if you haven't had problems yet, change them already.

 

If you have a coil problem, change all the plugs, because the plugs caused the coil to fail.  Also change all the coils, or at least the three inaccesible ones under the plenum.

I'm not having any problems, just trying to get ahead of problems. Toyota suggests every 120k, we had the original set replaced at 105k. Now we're at 186k. Just wondering if I should do them sooner rather than later. Car runs great. A/C not working correctly right now though. 

Do them now.  The modern long spark plug intervals kill ignition coils.   Without going into deep dork detail, voltage builds in the coil until it is high enough to jump the gap in the plug.  The older and more worn out the plug, the higher the voltage gets.  The higher the voltage, the more likely it is to find its way free elsewhere, either through the side of the now-incredibly-dirty plug boot, or the coil just shorting through its own windings.

 

Platinum plugs do last longer but IMO should be changed every 60k at the most to keep from killing ignition coils.  When you kill a coil, you risk killing one of the converters, which is often a vehicle scrapping event.

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