Well, the rear bank is an EXTREME
PITA to replace....just so you know going in
In overview, I'll document how to remove both the wiper/cowl box and the intake manifold. As previously mentioned (and posted below) some have gotten the plugs changed with the manifold still installed, but I found I could not.
Took 3.5-4 hours to complete.
Here we go again:
Grab a beer...your gonna need it
Make sure the wipers are in the fully off position. Then use some kind of tape (I used electrical tape because it was handy, painters tape would be better) to mark the position of the windshield wiper on the window. Its to align the wipers when you re-install them later.
Remove the wiper arms. There is a single nut at the end. Just remove the nut (its a 14mm nut) and the wipers pull somewhat straight off. You kinda have to push down on the spring in the arm (push the wiper toward the window) to get enough pressure off the screw threads to pull it off.
Next you need to release a small trim panel on each side of the vehicle (I don't know the name of it, but its this below)
All you have to do is pull that peice up toward the hood, then in the direction of the top of the window. It will release the clip/pin that holds it in place. Don't fully remove it as it uses some adhesive to hold it in place at the edge. You can let go and it will stay in place on its own.
Remove the top of the wiper/cowl box. There is a single push pin on each of the box that needs to be released. Depress the center of it with a small screwdriver, and it will disengage from the body panel.
To prep it to be re-installed, pull the "arms" of the pin back, and push the center "post" up till its above the surface. That way when you install it again, you press the center post to be flush with the rest of the surface.
Next you remove the entire top cover. It hooks under the windshield at one side, and clips into the wiper/cowl box at the other. If you undo those clips, it will slide away (toward the engine) from the window. (blue circles are where the clips are located on the panel. They will be on the engine side edge when it is installed. Your looking at the bottom of the panel)
There is a small space between the top panel and lower portion of the wiper/cowl box. To undo the clips, use a screwdriver, pushing it into that gap, to depress the clip's arm to allow it to come out.
Leaving you with this
Remove the wiper motor assembly
First you need to remove the electrical connections (2 blue circles). The one coming from the windshield will only be there if your highlander is equipped with the cold weather package. Those 3 wires are the windshield wiper de-icers (the package also includes heated side mirrors)
To keep the wiper de-icer wires out of the way, I taped it to the windshield.
Next you need to remove the 4 bolts that hold the wiper motor assembly to the car. They are all 10mm bolts and circled in red. The 2nd one from the left is under that wire harness (its completely accessible, its just the angle of the camera hides it.)
Remove the wiper motor wire harness. It is held in by 4 clips (red circles)
To remove the clips, compress each side of the clip while pulling back on it.
Remove wiper/cowl box. It is held in with a lot of bolts and a few nuts. On each side of the box there is 6 bolts/nuts that need to be removed. The ones below in blue and yellow cirlces are 10mm and are easy enough to remove. The ones in red though, are 2 of the 3 mounting points for the shock absorber/strut. They are 14mm nuts. They are on TIGHT (as they should be), just be warned its going to take a whole lot of force to break then loose. The other side is identical (except mirrored)
There are also 2 10mm bolts in the center of the box that need removal.
It will pull straight up and off leaving you with this
Now to give you an idea of how much space there is around the intake manifold, take a look at these pics. I found there wasn't and went ahead with the manifold removal.
From Passenger side:
From Driver side:
To give you an idea of how hard this would be....the grey wire harness seen above is DIRECTLY above the coil packs. It would need to be moved to remove the pack...and that's pretty hard with the manifold on.
Remove the tube connecting the air box to the throttle body. Loosen the clamps in the red circles. Remove the vacuum line in the yellow circle. And unhook the vacuum lines that clip to the tube in the blue circles. Pull the tube back from the throttle body and air box to free it and it will come right out.
Remove the throttle body from the intake manifold. Pull back on the rubber boot and remove the connector from the throttle body in the blue circle. Remove the 4 bolts that hold the TB to the manifold (they are 10mm) in the red circles
The TB has 2 coolant lines going into it (2 blue circles). I didn't want to deal with coolant, so I left the TB connected to them, and leaned the TB against the air box. It stayed there the entire install
Remove the misc connections to the intake manifold. The red circle is a connector for air surge valve, remove it. The yellow circles are vacuum lines. The far left one is on the back side of the manifold. Remove those as well.
Remove 2 bolts on the backside of the intake manifold that mount it to the engine. They are both 12mm bolts. The bolts are located on the engine valve cover, but are connected to brackets that are on the back side of the manifold. If you remove these 2 bolts the manifold + brackets will stay together when your remove the manifold in the next step.
On the passenger side of the manifold
On the driver side of the manifold
Remove 4 bolts and 2 nuts that hold the manifold to the engine. Now this part is VERY important. These have to be taken out in a specific order, otherwise it could warp the intake. (to give you an idea of how small the tolerance is, if the warpage of the 6 "openings" of the manifold to a flat surface is more that 0.1mm, toyota says to replace it)
The 4 red circles are 5mm Hex bolts. The 2 blue nuts are 10mm.
The order for removal is F -> A -> E -> D -> C -> B
Pull straight up and the manifold will separate from the engine. Leaving you with this:
Unbolt the engine wire harness to allow you to move it around to access the coil packs. First cover the intake openings. Then remove the bolts/nut (all 10mm). Red circle is the nut, blue circles are bolts on the valve covers, but the yellow circle, the bolt is on the side of the engine.
Unplug the coil pack ignition plugs (red circles) and the misc plug in the yellow circle. After that, you will have plenty of slack in the wire harness to move it around.
Remove coil pack (10mm bolts), remove old plugs, inspect old plugs, put anti-seize on new plugs threads, gap new plugs, install new plugs, install coil pack. Same procedure from the first post
Neat trick, found it in one of Dante's Taco's post. Tape the socket extensions and spark plug socket together to keep them from coming apart in the engine.
Notes about the plugs. The rear bank plug's were hard as hell to remove. The plugs took a ton of force to break them loose from the engine (unlike the front bank)
Also, just stick with a 6" extension here, there isn't enough space to fit a longer one and clear the firewall (when removing the plug/socket)
Driver Rear Cylinder:
Center Rear Cylinder:
Passenger Rear Cylinder:
1 of the plugs was gaped correctly at 1mm, but the other 2 were .9mm. So for the record, only 1 out of 6 plugs were gaped correctly from the factory. The rest were too small.
Re-secure the engine main wire harness.
Reverse of removal directions.
Put the manifold back on the engine. Time to secure the 6 bolts/nuts again. Like before there is an order in which you must install the fasteners. The 5mm hex bolts (red circles) torque is 13 ft*lbs and the 10mm nut (blue circles) torque is 12ft*lbs.
The order of reinstall is B -> C -> D -> E -> A -> F
Re-install the 2 bolts (12mm) in the back of the engine/intake manifold
Reverse step 12
Reconnect the vacuum lines and air surge valve connector from step 11 to the intake manifold.
Remount the throttle body to the manifold. reverse of step 10
Re-install the air tube between the TB and air box. Revere of step 9
Say a little prayer and start up the engine. Listen/feel for unusual vibrations, misfires, dead cylinders to make sure the new plugs are all working. If one isn't firing you will definitly know (very rough idle, strong vibrations). If you have a problem you have to take the entire intake manifold off again
Re-install the wiper/cowl box. Replace all the bolts/nuts mentioned in step 8. red circles are 14mm. blue and yellow circles are 10mm.
Torque ratings for various bolts/nuts: Red circles 63ft*lbs ------yellow circle 78in
*lbs ------- blue circles 78in
*lbs (same for the 2 10mm bolts in the center of the box)
Also make sure you use a quality socket extension... I nearly snapped the tip off of mine torquing the shock absorber/strut nuts in place
Reinstall wiper motor wire harness. reverse of step 7
Re-install the wiper motor assembly. reverse of step 6. The 4 10mm bolts' torque is 62in
Reinstall the top of the wiper/cowl box. Reverse of step 5. Basically push the cover into the window (making sure the claws meet the window correctly), then clip the other side of the cover into place. Be careful, the clips can break easily, take your time putting them back in place. Then put the 2 push pins back in their spots.
Reinstall the trim panel remove in step 4. Just push down, they will lock back in place.
First clean off the wiper motor screw threads, then re-install the wiper arms. Making sure to align the arms with the tape from the 2nd step. The arms can be mounted in any direction, that is why the tape is key. You will need to push down on the arms (to flatten the spring) so that the 14mm nut can be tightened down. Also hold the arm in place while you are tightening, as they can and will want to move. Torque is 18ft*lbs on the nut. Then turn on the wiper and make sure they are working normally and not hitting the car body anywhere. If they do, take the arms off again and start over.
Get more beer and relax
Let me know if you have any Q's, or typos above
6" socket extension
3" socket extension
5/8" spark plug socket
5mm hex socket
spark plug gaping tool
Disclaimer: Do at your own risk. I will not be held responsible for any damage to vehicle or bodily harm when performing these modifications, or any voidage of certain parts of your warranty.