Oh yes, you may have experienced or have heard of the painful reality of changing those 3 rear spark plugs in our beloved RX300s. I went through this yesterday as a prelude to changing out the brake pads later in the day. So let's put the ball on the tee and get underway. In this example, we never opened the throttle body.

What will you need:

10 mm wrench
12 mm wrench
1 3/8ths and 1 5/8ths (16 mm) socket and ratchet (or just use 2 5/8ths extensions)
1 5/32nds allen wrench
An extension magnet (not sure of the actual name in English, but you will see it later)
6 spark plugs (I use TorqueMaster plugs that I obtained through Carson Toyota, www.l-tunedparts.com, but you can read more at www.extremespark.com)

The Denso SK20 or NGK offers a number of options in their spark plug line, http://www.ngksparkplugs.com/part_fi...engineid=26738

If you want to remove the throttle body in order to get at the rear plugs as opposed to what I am about to show, see this thread, https://www.clublexus.com/forums/sho...d.php?t=291370

Shown below is an old TorqueMaster on the left and on the right a new TorqueMaster. One difference you can see is on the longer length on the side electrodes on the new one. This after a little over one year of use. Why would it look like this? Partially this is due to the foul gas I was using for years (Pemex here in Mexico), even though premium, high in sulfur and who knows what else, but also my use of racing fuels and other additives. The last plugs I had used, Densos, also had a similar appearance even though I had also used them for just one year.

I cannot emphasize this enough, make sure your spark plugs are properly gapped or you may have issues after installation.

 

Here is another view of those plugs before we begin.

 

First you need a 5/32nds allen wrench to remove the 3 screws on the engine cover.

 

After removing the cover, you will see this. The 3 front ignition coils.

 

The bolt on each ignition coil is 10 mm, which you will find is kind of standard across most, but not all bolts on the RX300.

 

One other shot as shown by my cousin Rodrigo.

 

Then simply pull out the ignition coil...it comes out easily with effort. This particular ignition coil is the one I replaced last year (the rest are all original) and had temporarily replaced with a modified Camry ignition coil until I could get one from the U.S.

 

You will then be staring at this...the actual spark plug itself.

 

Another topside view with all coils out. You can unclip the coils or just leave them to the side.

 

Now, use the 5/8s (or 16 mm) socket with ratchet and turn counterclockwise to loosen the plug itself. For the front plus use a long socket as shown, however you will see shortly our plan of attack for the rear ones.

 

Now, use a magnetic extender or extension to pull out the now loosened spark plug.

 

Ah, those beautiful front 3 plugs. You could just reach out and kiss them

 

I dropped the plug in (they are 4 pronged and are very strongly built on the tips), but for other brand plugs I would suggest using something like a pencil with some tape on the end to carefully lower them down so the gap will not be adjusted by the plugs banging at the bottom. Use the 5/8ths socket and wrench turning clockwise to tighten, put the ignition coil back in and use the 10mm wrench again to close.

HINT: keep one of the front ignition coils out to serve as a guide for the rear plugs.

 

Now, time for the rear plugs.

You can either do this step now (we did not but I advise you to do it at this point) or wait until you get to the furthest right plug. You need to use the 10 mm wrench again to remove this cable.

 

Another shot.