Rear 3 spark plug Highlander V6

Bwahahahahaha! Yeah, it's a pain in the ass, though. If you remove the PCV hose and the ground cable connected to the passenger side of the plenum, you should be able to get in from there. You'll need an assortment of basic hand tools to experiment with until you find the right combination. If I remember correctly all I needed was a 3" extension, a spark plug socket, and a 4" ratchet. It takes some patience, and later that day it'll look like your forearm got attacked by a squirrel, but it's not so bad.

I've heard that it is possible but painful and difficult. I just changed my spark plugs and removed the plenum. I wanted to take out the mass air flow sensor and throttle bodies to clean them and the plenum was pretty easy from there.

One problem area was the plenum support against the fire wall ('01 Highlander). The bolt is inside the bracket and there isn't enough room to place a socket and ratchet on the bolt head to remove it. I finally removed the whole bracket from the bottom. I installed several washers to get the bolt head away from the bracket enough to get a box wrench on it (for next time). Hopefully Toyota fixed that issue in later models.

You will want to take several pictures of the engine and mark and number all the hoses as you remove them to make it easier during re-assembly.

One word of caution, if you remove the throttle bodies, there is a couple of coolant hoses attached to the bottom (they look like large vacuum hoses). I didn't believe the service manual that I had to drain the radiator until I unhooked one of those hoses and red radiator coolant came out.

Good luck, Paul.

Thanks for the information! I have 90,000 miles and I pulled the front

3 plugs and they look great. So I will wait for another 20,000 miles or thereabouts.

nobody wrote:

I changed mine at 106,000 miles. They were worn but came out nicely. My gas mileage increased about 2.5 miles per gallon with the new plugs, cleaned mass air flow sensor and throttle bodies. Don't forget to put a good quality antiseeze on the spark plug threads when you put new ones in (or even the old ones).

Paul.