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RX330 Rear Spark Plug Change (***DIY with Pics***)

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RX330 Rear Spark Plug Change (***DIY with Pics***)

Old 04-03-17, 01:45 PM
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Just finished this job. Took me all day. Reason? Those two bolts in the back of the upper intake manifold. When he says they're a ^%$*% to get to, he is not exaggerating. It didn't help that I have monster mitts for hands. The trick to lining up the bolt holes is to leave off the manifold bolts to the lower manifold. Start the passenger side (14mm) bolt first, but ONLY start the threads to the point you're satisfied it won't come out. Then, start the driver's side (12mm) bolt. I recommend leaving both of those mostly loose or just slightly firming up and then installing the upper manifold to lower manifold bolts. Go back and tighten those rear bolts last.
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Old 06-05-17, 08:37 AM
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Had a P0304 Error Code (Cylinder #4 misfire) along with associated warning lights and light engine shuddering. Diagnosis brought me here. I took out the coil and plug and it looked fine. Put it back together and error codes are gone and it runs like normal. Must have been a loose connection. But I was thinking on replacing the old plugs (probably 150k on factory plugs). I was thinking while spending all this effort to access the back plugs, it would be worth it to replace the coils as well. Any thoughts? Most seem to recommend only replacing them if they go bad. Maybe just replace the rear ones, and wait for the front ones to go bad???
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Old 06-05-17, 09:15 AM
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For access reasons, replacing the rear coils is probably a good idea. They can also be saved and used to replace the front ones if they go bad.
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Old 06-05-17, 10:21 AM
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Spark Plugs should be replaced at 90,000 miles, yours certainly did some overtime.
I second Mylexbay's recommendation, no point to experiencing the same painful DIY for at least the next 90,000 miles.
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Old 06-19-17, 12:25 PM
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My wife's 2004 RX330 was due for the spark plug replacement and I had been wanting to do the spark plug for almost 2 years after first reading the instruction posted here. But I read online that others have changed the plugs without removing the plenum. I made it a challenge to do it without removing the plenum. I was successful at the end, but if I were to do this again in 120K miles, I would probably pay someone to do it because it was a PIA like everyone has mentioned, either removing the plenum or not removing the plenum. While replacing the plug is not a skillful task, the act to get to the rear plugs were. I ended up using almost 2 days to replace the just 3 rear plugs. I did work very slowly and I dropped screws/tools down the engine which slowed me down a lot. Again, I would think twice before attempting this because life is too short. And for the Toyota engineers that came up with the design, let me say "Thanks Genius!"

This is not intended to be a complete top to bottom instruction, so I won't write about replacing the front 3 plugs. Also, if you need the instruction for the front 3, look else where and think twice before attempting the rear 3 plugs.

To remove the left 2 rear plugs, this is what I did.
1. From the passenger side, you see the what looks like a Cruise control vacuum module on the left of the plenum, it's held down by 4 screws, remove them and you can move the valve back and forth to allow the entire cruise control module to pop out enough to clear the PCV valve. (pic1)
2. Remove the hose connected to the PCV valve. warning, it was on very tight and there was almost no space to remove it. I used an opened end adjustable wrench. to remove it.
3. With the PCV out, you can see the first spark plug and wire. (pic 2)

4. Going by memory, and skipping much of the details to include using a small GearWrench Combination Ratcheting Wrench to loosen the 10 MM bolt holding down the ignitor. I used an universal joint and 1 extension to remove the first 2 plugs from the left. There's very little space to work with despite having relatively small hands. You want to make sure that you use a normal long neck 5/8 socket or a spark plug socket without the rubber gasket to hold the spark plug in place. This is very important because there's simply no space to pull the tools back out and the rubber gasket was offering too much resistance to pull the socket back out. Instead, I dropped the socket in, then the extension, follow by the universal joint. After a lot of trial and error, I found just enough clearance to tighten the left 2 plugs from the passenger side. After tightening down the plugs, I used my flexible magnetic snake to retrieve the extension and socket from the spark plug well.

5. Put the plug ignitors and PCV valve back. BTW, I replaced the PCV valve because I had it out, but mine at 120K miles still rattled and there was little signs of wear. I imagine it is a life time item and doesn't require normal replacement.

6. Took a break and congrats myself. I actually decide to call it a day.

7. I started the right side by trying to remove the plug without taking the air intake off. I could get the 10 MM screw that holds down the igniter, but there was not enough space to clear the spark plug. So start by removing the air cleaner and air intake. I didn't take pictures so follow the instructions from others.

8. The air intake valve was held down by 4 screws. after removing them, you can push it aside without disconnecting the coolant lines. I ended up disconnecting the coolant lines to do a deep clean of the butterfly valve. (Pic 3)

9. Remove the metal air intake extension that connects to the Plenum. With it out of the way, there's just enough room to take out the right plug (pic 4)

10. Use the same method and tools as other rear plugs, remove and replace the last plug.

11. wash your hands and see how your hands fared after this project.

Hopefully this helps for those brave enough to try it. I would be paying someone to do it next time unless I have plenty of time. I am happy that I took on the challenge though. The spark plugs were all in decent shape for being in the engine for 120K miles and I think 90K is probably a little conservative. But if you want to change them at 90K, no harm done other than your wallet.

Last edited by rlin78; 06-19-17 at 12:51 PM.
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Old 12-10-17, 06:29 AM
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I just changed the plugs on my 2010 rx 350. I made a YouTube video about the process. I removed the cowl not the intake.

Faster method to change spark plugs on Lexus RX 350/ Highlander
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Old 12-30-17, 07:40 PM
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Took over 6 hours with the additional work of the valve cover gaskets. Glad I did though, some signs of leaking and I guess all of the heat cycles loosened the valve cover bolts to about finger tight over the last 12 years.
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Old 03-03-18, 07:05 AM
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This is my 2nd RX330 valve job.
I am still having problems with the plenum bolts going back in
Any suggestions when putting them back together.. Should I try from underneath?

My 2nd time experience.

1. I placed labeled bolts in bags this time
2. I made sure to mark vacuum hoses.
3. I had a catch towel to absorb all the coolant
4. I placed the tube seals in the proper direction (see picture..The 2 on the right in the picture is the correct direction)
5. I removed the TB and the right Plenum bracket from the plenum and the engine so there was more room at the back.
6. I removed the wire harness nut holding the wire harness on the right of the engine (this helps when removing the rear valve cover

Problems the 2nd time around
1. Driver wiper did not want to come off. So I had to remove the plastic cowel/arm assembly with arm in one piece (I was able to get my under the cowel to remove the bolt
2. I broke the middle coil pack clip (it just broke apart. I hope it can stay in somehow) Anyone know if I can replace just that one?

Other Tips on removing rear valve cover
The far right bolt can be removed with an extension and a 10mm socket (no problem)
The far left bolt can be removed with a flex socket wrench and an extension
Also I attached a picture how to use the pliers to bend the tabs on the tube seal
The middle two bolts can be removed with the stubby ratchet 10mm

attached are some pictures showing the half moons which I left alone.
In one pic you can see towards the middle I have some sort of carbon build up?? I just scraped it of? Is it carbon or is this considered sludge?
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Old 08-20-18, 11:21 AM
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In everyone's opinion that have tackled the spark plug replacement.... is it necessary to replace all the gaskets when doing so or can the OEM gaskets be reused? appreciate the help, thanks in advance...
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Old 08-20-18, 11:34 AM
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I would, if you reuse and it doesn't work, you have a LOT of work to do to get back in and fix it. Especially if it is an intake gasket.

Rockauto has them pretty inexpensive.

IF you have a lift at your disposal, you can drop the rear engine cradle from the back side under and go in from behind the engine and have it done much easier, no taking the intake off to get to the rear plugs.

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