Spark Plug Change
 

After dealer quoted $650, I have decided to take care of it myself. With that note, work hour charge is 4 hours and it took me literally four hours to complete. Knowing what I know and the location of the rear bolts, I can probably do this again in 2 hours. Spent too much of time looking for shortcuts but best method is to remove everything IMHO. For a week, I was online looking for the location and may be shortcuts to removing the intake but only thing that came any close was a Youtube video of two person removing hood in a fast video mode. This is the only Gen3 I can find. Most of them were for Gen2 RX and bunch of Highlander. Gen2 is similar but first bolt location is easier to reach in Gen3 RX.
Before you start, make sure you can do this outside on a sunny and good weather day. I have started to tackle from inside the garage but couldn’t see much even with two separate shop lights [smaller lights].
- Remove everything out of the way. Includes cowl and wipers. Out of four hours spent, I spent 30 minutes looking for screws I can’t see nor identify. Knowing where two screws are location [pictured below], I may be able to do this from the bottom if I had a lift but still challenging.
- Removal of cowl, wiper arm, and all the trims will take about an hour. Putting back was easier and took about 30 minutes.
- My 2010 has 118k, plugs looked “healthy” but noticed more “wear” on #2/4/6 plugs [front of the vehicle]. These three plugs have notables wear on both tips of the plug compared to #1/3/5 plugs.
- Also the plugs #2/4/6 were more difficult to take out [more resistance]. Also the electric plug clips to the coil have all broken off. But all three #1/3/5 clips were fine. I am not worry since I can get to #2/4/6 without taking the intake off if I have a problem later.

Plugs came out of RX and replaced with same Denso Iridium Long Life - FK20HR11.Overall, it’s time consuming but fairly easy task if you are attempting this on your own.

https://cimg9.ibsrv.net/gimg/www.clu...af86bb105a.jpglooks rough in the picture, but it's fairly easy to remove both cowl and wiper arms.
https://cimg0.ibsrv.net/gimg/www.clu...474ebd108b.jpgthis is the rear view of the intake. First bolt is right near were throttle body meet.this one is easy to find and remove.
https://cimg1.ibsrv.net/gimg/www.clu...f3c574e62d.jpgthis is the top view of the intake. notice, #2 bolt, there is plenty of space to grab and remove.

I must tackle this in a few thousand miles. I too only saw Highlander videos. Nothing really specific on 3rd Gen Rx. Do you really need to remove the cowl and wipers? How about wiper motors? Also, where did you get the parts, (spark plugs, intake gaskets) ? Thanks for sharing.

When I watched the various youtube Highlander spark plug replacement, its just freaked me out.
Then I realised that they might be doing it the hard way. The easier way would be to remove the entire windscreen wiper mechanism and cowl area instead of dissassembling the intake manifold.

I will be following this process when the time comes:
The intake manifold is untouched doing it this way.

Also, in the process of researching spark plug changes, I've found a lot of youtube videos on fake NGK spark plugs, particularly ones sold on eBay.

I'll be sticking to genuine (Toyota/Lexus - Denso?) plugs just to be on the safe side.

Also, I will replace the ignition coils on the rear bank, just coz coils can go bad, and keep the used one as spares in case one of the front coils fail.

This is one situation where less is more - I could have bought the RX270 (four cylinder engine) where the spark plugs are relatively simple to replace.

If you do remove the wiper arm it would be a good idea to replace your valve cover gaskets as well if they are leaking

If the rear rocker cover gasket needs to be replaced, then the intake manifold will definitely need to come off, as it is bolted onto some part of the rocker cover. What a big job that would be then! Thankfully I haven't heard much about rocker cover leaks but no doubt as the miles pile on, it will be inevitable. One of my relatives has a first gen Lexus with a leak on his rocker cover. His local mechanic found a resin which is applied to the leaking part of the gasket and that was sufficient to not require a gasket replacement.

Guy who did plugs on my 3.5V6 did NOT remove plenum. The hardest job he had to do was to plug coolant line on the R hand engine side, behind plenum, to remove some part that was blocking access to the bank 1. Come to find, there are coolant line plugs out there and, as it was at the system high point, he didn't let any air in. Took him 1.5 hr to the tune of 200 bucks. He had cowl removed. That's it.

I will be doing this job in the upcoming months and will be removing wiper cowel, plenum and changing out the gaskets. WIll report back with DIY
I have done 2 2005 rx. The bolts on the back are not impossible to put back in. Just takes patience

https://cimg6.ibsrv.net/gimg/www.clu...ce8468329c.jpg
Did this project and did not remove intake. Also did not remove any coolant plugs or lines. I used the the video previously posted about faster way to change 3rd gen spark plugs https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DHzUGqZYBFb4&ved=2ahUKEwjjovyh86_eAhVJzFQKHUE2DsAQwqsBMAB6BAgJEAU&usg=AOvVaw2ldOczQrcRTo6nNpTwEb2v.
also used 2nd gen Highlander diy on spark plug change on removing the cowl and some torque specs: https://www.toyotanation.com/forum/122-highlander-2nd-generation-2008-2013/413790-diy-2gr-fe-v6-spark-plug-replacement.html#/topics/413790?page=12.

some caveats..one of the bolts holding the wiper motor assembly is hidden under the driver's side plastic piece that you lift off but don't completely remove as seen in pic

In addition to the bolts and push pins for the plastic cover over the wiper motor assembly, the front side is held in by plastic tabs that fit into slots of the metal cowl, as shown in the attached 2 pictures
https://cimg3.ibsrv.net/gimg/www.clu...ce2b43ba5a.jpg
https://cimg5.ibsrv.net/gimg/www.clu...aad596aef6.jpg
you can use a screwdriver to push the tabs in a little to release, but I just pulled straight up and they came undone easily without breaking

In the YouTube video, the guy talks about moving a wire harness after disconnecting 3 connectors from the passenger side, and the three coil pack connectors behind the intake. But, the harness is clipped to anchors as shown in the pic. Screwdriver pointing to an example. To release that hold down lift on the grey tab WITH flathead screwdriver as in other pic and the lift grey block up off metal tab. sorry, I cannot seem to get the pics to post on order.
https://cimg2.ibsrv.net/gimg/www.clu...5b76992638.jpg

https://cimg0.ibsrv.net/gimg/www.clu...411688134f.jpg

Once you unclip the grey hold downs (there's 3 of them behind the intake), and the plugs to coil packs, the wire harness can be moved out of the way to access the coil packs and spark plugs. For me the absolute hardest part was removing the plugs from the coils. The pic shows the passenger side bracket unbolted like in the YouTube video but I left one bolt loose just to move the bracket. The YouTube guy removed the black bracket seen on bottom of pic. You can see spark plug hole, and wire harness on top of pic. The grey block attached to the shiny metal bracket top right of center of pic, so I moved the wire harness towards the firewall (left in the picture, intake to the right)
https://cimg3.ibsrv.net/gimg/www.clu...dbbfb70c65.jpg

The plugs all looked about the same... old ones (on the right) at 115k miles has some wear at the electrodes, almost looks like corrosion.

I hope these little pointers help someone, as I had to discover it the hard way since the YouTube vid wasn't all that detailed, and the Highlander diy did the intake removal. Honestly I don't know if I saved time by not removing intake, but it's less to screw up if the intake isn't torqued down just right. My idle is noticeably smoother and I saved about $700 dealer wanted over $800 here, Indy shop about $700. Although the torque specs for the spark plugs is 13 ft-lbs, it seemed several turns more then if you follow denso's recommended procedure to hand tighten until it bottoms, then ratchet another quarter to half turn, then one more 1/6 the turn. Doing that was plenty tight, and 13 ft lbs kept going so I bailed on the torque specs and used denso's recommended method. i did one plug to spec, but decided to back it up to denso's recommended. Also, what I think is essential in this project is a 5/8 spark plug socket with a magnet. Good luck!
https://cimg1.ibsrv.net/gimg/www.clu...b5f1bd0d49.jpg

Changing the Three Rear Spark Plugs
 

2015 RX350 FWD, 34,300 miles.

I removed all four of the engine bay dust covers this morning to have a good look at the layout and condition of the various components underneath. It appears to me that in order to change the three rear spark plugs on this 2GR-FE V6 engine, the intake manifold must first be removed. True or false? If true, what a bummer.

True, but spark plugs last a long time. Install iridium plugs at 100k, and they will last another 200k.