teddyd

I have to change the plugs on my 2008 RN400h. I've heard so many horror stories about the three rear plugs that I am hesitant. Has anyone done this without the need to disassemble the engine? Thanks.

spacecraft

I'd guess that It should be similar to the 330, which was very well explained in this thread:
http://www.clublexus.com/forums/rx-s...with-pics.html
I've not yet seen any 400h-specific instructions, though.

thomas1

The intake and filter box are different.....mine too is due, but I am going to stretch it....

maximizese

We have 120K miles on our 07 Rx and just recently replaced the timing belt, tensioners, water pump, radiator, and CVT fluid. I don't think I'll be changing the spark plugs myself...maybe just the front 3. I've replaced spark plugs from other FWD V6s, but this just looks like too much work for me.

jakenbake

I am all about doing maintenance myself, but after reading up on how to do the spark plugs I opted to have the dealership do it.

thomas1

You have to remove intake manifold for those rear plugs....that's life....but I will tell you these plugs would probably go easy 200k miles.

smassey321

Spark plugs are almost as much work as timing belt. Don't do them too early. I wish I had waited until 120k miles.

proudpilot

Working on the spark plugs right now. Absolutely have to remove the wiper cowl to get to everything. I'm 3 hours in and just about ready to take the intake manifold off. Getting to the throttle body wasn't so bad. However, past that there are a number of bolts that are tricky at best if not impossible with the wiper cowl on. I'll let you know how it goes.

proudpilot

Ok, so I didn't take photos, because this kicked my butt. The process is basically start at the front and unhook everything back to the intake manifold. The coolant from the throttle body was annoying, and a few of the bolts were REALLY on there. This is a 140K mile 2007 RX400H. Some wear and tear, but not horrible. I got all the way to the back 2 bolts of the intake manifold, and for the life of me I cannot figure out how to get them off. There is just so little clearance that you basically can only get a closed wrench over it. My 3/8" drive ratchet with a short 12mm/14mm socket on it was too big. So with a short socket, and barely any throw, I can't get them loose. I tried for 2 hours, I just can't do it. There's no room to swing a mallet to help it out, and a cheater bar is out of the question without removing a LOT of lines.

Also, you absolutely have to remove the wiper and wiper cowl for the RX400H. Unless you're 8'11" and 100lbs that can bench 300lbs, you're not getting the bolts off. You need some room even with clever extensions. The wiper cowl covers about 1/2 of your work, and it's so much simpler when it's gone.

So I'd like to do a write up with photos/videos, but any ideas how to get those 12mm and 14mm off the back intake manifold? Is there a special tool, did you drill through the dash, or is there a magic wand I can borrow?

Thank You

Brouwersj

I did this job over the last weekend. Found it quite enjoyable actually. It was my first big job on our 2006 which we've now had for half a year almost.

Removing the wiper cowl is a must for accessibility. I did not remove any coolant lines but removed everything else from the throttle body. This way I could remove it from the intake and just put it aside. Removing the bolts that connects the rear stays to the intake is the hardest access wise, as you can read in all threads about this subject. I had no space for my ratchets, so used a simple open end wrench to undo them by half a turn maybe, the rest I could do by hand. Plugs in my European spec RX were NGKs which I believe are the factory plugs. They looked ok after 100K. Next up for me is the timing belt.

SkiMe

I changed out my 07' 400h. Definitely have to remove the intake. I did the job 3 times because the coil packs went "bad" because I touched them. Don't really know why, but once disturbed, they started faulting.

Here is the thread I did with pictures and some direction. Be sure to click on each photo to enlarge....

https://www.clublexus.com/forums/rx-...ge-rx400h.html

proudpilot

I got a bit behind on my schedule. I did this a month ago and I need to do a few grammatical corrections. However, here is the full procedure, with tools needed, parts needed, and photos. Read through the whole thing before beginning. Good Luck!

I'll figure out how to do higher resolution later, but the pdf with high res was 200kb too big for the forum. Suggestions appreciated.

thomas1

What a fantastic write up with pictures...I will now attempt in one hour change of plugs at 247k miles...Also clean throttle body...and change pcv valve.

thomas1

OK, done three years late, and 125k miles late. Yes those rear two bolts on intake housing are a pain. Once off, I cut the passenger bracket loop off and it made putting the bolt back in so much easier. The plugs, were at 248k were quite ragged looking. The gap was fine, but the metal was really rough. I put three new coils in rear cylinders with the plugs. I also replaced PCV valve, plenum gasket, air filter, and cleaned MAF sensor. Yesterday the car was throwing P3191 code and engine appeared to start for about 8 seconds and shut down. I hope these efforts fix this code, time will tell. Car ran fine tonight, but I am going to perform an ISC reset tomorrow. For a guy that has always done maintenance and preventative maintenance I am ashamed that I let this car go so long. Oil changes are on time but those plugs and throttle body need replacement and cleaning. Took me thirty minutes just to clean throttle body from the gum. Yup 12 year old car and 248k miles. Keep them rolling.

daddiojigg

Great idea to cut supports! I imagine you then reinstalled manifold with screws/bolts already installed loosely on manifold and slip over slots? I love this forum ! kudos to all who contribute.