thomasfx10

Great instructions ... I would like to add some additional info ...

1) I highly recommend taking off the windshield wiper cowling. This is easy to do and will only add about 40 minutes (20 off and 20 back on). Note: Make sure you have a larger socket wrench to break the 2 strut nuts (14mm) that need to be removed on each side. I had a cheap socket ... Autozone will let you "Rent" a breaker bar free ... Just save the receipt ... takes 14 mm socket.

2) Once the cowling is off, everything is sooooooo much easier to access. Before this ... I tried for an hour to get to the back passenger side bolt but I could not. AND ... you have to know exactly where it is located ... Also ... I would not worry about putting the passenger side bolt on again. It does not appear to have a meaningful purpose (accept to give you a headache)

Anyway ... Once the cowling is off, you can get to it with no problem. It also gave me time to clean / lube the cowling and wiper assembly / motor.

3) This has been said before ... when taking off the elect. clip to the coils be very careful ... They are old and break easily ... I broke two ...

4) You only need to replace two gaskets ... One for the TBI and the other for the manifold. I ordered kit that had an extra gasket that was not needed.

If I knew what I know now ... Total time = 4-5 hours.

Rainbird

They are indeed a PITA, fortunately they don't require replacement until 120K miles.

nwfsnake

I completed the spark plug change last night on our '07 RX350. Took about 6 hours total.
I also recommend removing the wiper cowling, made things so much easier. Removing the cowling is about the easiest part of the job!.

I was able to use a short, flex head 3/8" socket wrench with a 2" extension and a regular 12mm socket to remove the back left bolt from the intake. You go under the wire harness that is in the way with this method. It still took about 30 minutes for me to get the correct angle and extension/socket combo with the flex head, but once I did it came off easily. An inspection mirror is your friend with this bolt!

Everything else was not bad, with the wiper cowl off you can move the wiring harnesses around
to get to the back spark plugs and coils easily. I removed all the brackets and connectors from the big harness that is in the way so I could manuever it to whatever position I needed to remove the coil and plugs. I replaced all three back coils with new units, don't want to have any failures before I have to replace the plugs again! I also used new gaskets on the intake and throttle body. They are cheap, so why not?

Thanks again for the detailed instructions OP! Nice job!

All I need to do now is replace the serpentine belt. Now where are those instructions???

genedjr

$500 to do this. Fortunately I will be doing it. This thread will make the job alot easier. Thanks to everyone that contributed. All the info is greatly appreciated.


...gene

Finsterow

Very detailed and good post

Thanks

trevyrd

Rich

This thread was an AMAZING help as I just finished the work on changing the ignition coils/plugs on my 2007 RX350 AWD.

I want to say "Thank You" for the step-by-step guidance.

Concerning the rear (surge tank stay no. 1 bracket) bolt, the 2007 used 12mm on both the right rear & left rear bolts. After a frustrating 3-4hrs, my brother was able to remove the bolt in a matter of minutes with a 12mm deep-welled socket. His hands/arms were slightly smaller than mine which enabled him to use his left hand to guide the socket and right hand (around the right side as you suggested) to attach and remove the bolt.

Again, great job & thanks to everyone who contributed to the thread -- it helped enormously to getting ahead on this job!

I'm pretty positive I can do the work in under an hour in the future... hopefully we'll have a GX460 by that time.

Cheers!
Trevyr

whh333

Like many others, I just want to express my appreciation for the time you spent on this really helpful write-up. I did the job in 6 hours taking my time and it turned out great. I made my original plugs go for 180,000 miles and they looked like they could go some more, though I am sure it would be better to have done the job after the recommended 120,000 miles.

I am glad I ordered new gaskets for the intake and throttle body. The old ones would have worked OK, probably, but the new ones were definitely more pliable.

I used NGK plugs, having had some issues with Denso's in the past.

In my 2008, like the post on the 2007, my "bolts from hell" on the rear of the intake manifold were 12mm.

This job had its frustrating moments, but turned out fine because of the detailed instructions you provided. In a masochistic way, I wanted to do the work myself because it lets me see the condition of the engine firsthand and know what to anticipate for the future. You just cannot get that turning it over to someone else. I use Mobile 1 Synthetic Oil, and it looks like this engine will go another 180,000 miles.

Best to you on your future projects.

whh333

lexisaurus

Hello folks. Great thread. Can anyone advise if there would be any differences at all on the JAP assembled version? Thanks!

mandyfig

There should not be any difference in Japan assembled RX. Imagine traceability issues if they deviated something.

kennytbone

Thanks for the walkthrough. I was able to change out a rear ignition coil in about 3 hours and I'm pretty sure I can do it again in under 2 hours. One recommendation I have that I don't think has been mentioned is to get all the intake manifold bolts started before tightening any down. The holes allow some play and after torquing down the bolts on top I was unable to start the bolts on the back. I backed off the top bolts and the manifold moved enough that I could get the back bolts in. Other than that, the entire process went exactly as described.

wildbore

To all the folks that completed this; you are mechanical wizards with superhuman powers. I just attempted it, and my first advice to anyone who wants to give it a try is; DON'T. If you have enough money to buy a Lexus, you have enough money to get someone else to change the spark plugs.

To all those (like me) who didn't listen to sound advice; As some others noted, definitely remove the wiper cowl. Those 30 extra minutes will save you years of your life. Once the cowl is out of the way everything is fairly accessible (even The Bolt of Doom). Seriously, all this was not that hard with the cowl removed. I don't see how it's possible to get to those bolts (much less the coild and plugs) without removing it. However, once the intake manifold was out of the way, that's when my real problems started. It does not seem physically possible to get the coils out. The cylinder is angled at the firewall with about 4" of clearance. Even if you can get the wiring assembly blocking the coils out of the way, the 6" long coils get wedged against the firewall when you try to get them out. After that, how am I supposed to get a 10" extension down there to get the plugs out? After 6 hours, I just gave up and put it back together. I still changed all the gaskets and the front coils and plug, but left the rear ones in place.

I love working on cars. I don't do to much more than routine maintenance on the Lexus, but this was the first time I've ever given up. I probably should not have given up so close to the finish, but I had spent way to much time already on just changing spark plugs. I don't think mere mortals are mean't to work on these.

FloorJack

Its about that time..

I think I'm gonna give it a shot.

Too bad its not designed like some GM's where you can just undo a motor mount and pull the engine forward...

dcdyd

I saw a video on youtube for . If anyone tried that method, does that mean that just with the wiper cowl off, it is possible to access all three plugs at the back?

dcdyd

The answer to my own question is NO. The Youtube video was on a 2010 Highlander and probably applicable to Lexus from 2010 but I don't know. For my 08, I can't access to the coils after removing the wiper cowl. I still need to take the intake off. But with the wiper cowl off, it is much easier to work in the area.

It took me 8 hours in total. Partially because this is my first major project which I don't want to mess up and partially because of below several reasons.
1) I am short, 5"3. I can't even reach the back of the firewall even with the intake off. I had to lay on the car with face off and support my body using my arms on the engine with my knees on the front bumper with some cursion. YOu can image that you can't be in that position for longer than 5 minutes and I need to take rest often. ANd also in that position you can't use your full strength which makes the progress slow.
2) The three rear coils are blocked by a huge bundle of wires and you can't separate it to make more room. I had to lose all screws of the supporting brackets and stretch the wire bundle to the maximum it could in order to take the coil out. So I totally understand what Wildbore feels when he saw the bundle of wires. In the beginning, it seemed to me that it is impossible to get the coils out. But with a lot tries, I finally managed to get it out and get it in. You need to utilize all space you possibly could and you need to insert the coil in an angle and turn it to the position the screw can be tighten. Had a lot of try and failure before success. It is easy to break the coil, so process with caution.
3) It is a major pita to get the coil plug off because if the tiny space. It took me probably two hours to get the three coil out. The most difficult one was the left, passenger side, due to the tiny space. I had a make a tool using a flexible metal stripe in the same width of the tip on the plug and carefully insert it into the edge and then to the bottom of the tip to lift it up.

My 08 is about 100K miles and among the 6 plugs I took out, two have already worn out and measured at 0.055 inches. The spec is 0.043. Both are at rear and one is middle and the other is the left one. I am glad that I did this to avoid some trouble.

The job is difficult, especially to me. But it is still doable. The most you need is patient.

Really appreciate rxs0 to explain the process in such a great detail and I can't think how I could do this without it.

jk00.rx300

Fantastic writeup! I had previously changed plugs and coils on our 2000 RX300 (RIP), without pulling anything major off the engine or dismantling the body. Well, I've now just about completed 6 plugs and the back 3 coils on my wife's 2009 RX350, with original plugs at 160,000 miles. A couple of comments- the 2009 also has 12mm bolt heads on the bolts in the back- they're 8mm x 1.25 x 20mm bolts, to be complete. I wasted probably 90 minutes trying to get to that back left (passenger side) bolt. Sheesh! Finally took the cowling off in about 15 minutes, which gave me enough room to make it possible- still very tight, but now barely possible. Putting that back left bolt in was almost as tricky as getting it off. First I did a fit check of the bracket itself to the tank to make sure it lined up. I could tell using a mirror and flashlight, and had to lift the tank off, tap the bracket clockwise a few times, and repeat, but I got it aligned nicely. I tied a piece of twine around the bolt, up near the head so hit hung on the twine horizontally, and dangled it from my right hand while I reached over the top with my left hand. I could touch the head with two fingertips, and after a dozen or so tries, I got it to start in! I also got pretty good at fishing tools and bolts out with my magnet. I found that if by taking the front tire off, I could reach in with a long handled magnet and usually get what I dropped. When I was done fishing, I lowered the car to a very low jackstand so the car knelt with the brake rotor almost on the ground. This extra few inches helped me reach over the engine. I'm at 8 hours, and still have to replace the cowling and wiper mechanism.... Maybe I could do it in 5 hours a second time, but I'll never know.

Thanks for the great writeup! Jim