aleksg

Hi guys. I just got RX300 few weeks ago year 2000 but i am struggling to find the 3 spark plugs. The ones in the front i changed but the ones i cannot find are somewhere in the back. Does the manifold have to come off to change them. I would really appreciate some input.

Thanks in advance,
Alex

Lexmex

Welcome to the Club.

They are a major pain. You don't have to remove the manifold though, https://www.clublexus.com/forums/sho...d.php?t=264967

jeremyp111

I used those instructions last weekend to change them out on my 2000 RX300. Not hard, just time consuming. Take your time and you'll be fine.

Blkongray

Having the right tools helps a ton (and small hands... guys with big 'catchers glove' hands will have a hard time getting to those back three). I bought a stubby flexible socket ratchet head and it helped tremendously. Also having a selection of extensions is key to making the job easier. Lastly, I had a sparkplug socket with a flex joint on it, and that really helped for pulling the plugs up and out of the well, then being able to pivot and tilt the extension to aid in getting the plug out. I took off the cruise control cable mount as suggested in many write-ups. That helps a lot in giving you access back in that area.

As Jeremy said, it's not hard, just a little time consuming and you need to be able to work in tight spaces without visibility (meaning by feel).

aleksg

Thanks very much for those instructions they did help a lot but we ended up removing the manifold. The 6 air pipes that the manifold comes on top of look very strange to me and i was curious about something. 3 back pipes are black, dirty and the three forward ones are clean, well cleaner. I was curious to know if that is normal or is this showing ome signs of problems coming up ?

Lexmex

Well removing the intake pipes does have the advantage that you get to clean them.

What you found is consistent with the way the motor functions. There are two hoses, one off the front bank with a hose that connects to the air intake just after the MAF sensor. And there is a another one on the left side coming off the rear bank where the PCV (positive crankshaft ventilation) valve is (I will show photos in a few minutes). Both of these redirect gases and unfortunately a bit of raw oil itself back into the intake manifold and air intake (just after the MAF) to be reburnt into the combustion. This is emissions related.

This has the unfortunate side effect of 1. coating the inside of your intake manifold and 2. making your engine run like it is on lower octane. In the case of #2 in the long run, you can get some knocking and predetonation, especially if you don't change your oil at regular intervals. This is because the oil gets into the air/fuel mix in the combustion and oil doesn't burn very well in that situation.

However, you asked why one part of the intake manifold was clean and not the other. I will answer that shortly with some photos as that is related to the RX300 having a dual throttle body.

Lexmex

Here is the PCV valve. This looks different on 2001-2003 models, but it is in the same area, just under the intake manifold to the left side. That shoots some gases and a bit of oil back into the intake manifold, but not as much as the area in the next photo.

Lexmex

Now here is one of my old intake designs. Note the blue arrow, that is where the front engine bank shoots its gas and some oil back into the air intake.

Lexmex

And the hose on the front engine bank itself with the blue arrow This is the unfortunate miracle of crankcase or crankshaft ventilation.

Lexmex

Now, on some vehicles there is something known as a crankcase or crankshaft ventilation filter and sometimes an optional oil catch can. Basically the bits of oil go into the can and the vapor and gases go out a small air filter. My cousin has the air filter on his Golf VR6. However, here is such a modification done to my friend Michael's Z06 Corvette we did just recently at a local shop with a catch can and crankcase oil filter. (see photo below)

My next upcoming modification will be two add 2 crankcase air filters with an extended hose from each bank, I will then add the air filters to each of these hoses and use plastic ties to tie the lines with the filters somewhere behind the engine block. I have seen this partially once on a Toyota Sienna that also shares a 1MZFE motor similar to our RX300. I will then block off the hole on the intake manifold and air intake with a bit of duct tape before finally putting an aesthetically sound rubber or plastic cap over the two areas to prevent any vacuum leak.

Now, let's show why one part of the intake manifold was dirty and not the other.

Lexmex

Here is the throttle body and notice the one on the left is dirty than the one on the right. Keep in mind the that the hose from the front bank empties on to this side of the air intake and that is the main reason that one bank gets dirtier than the other. I also noticed this when I clean the black baffle piece that hooks on to the throttle body.

There is one more picture to show.

Lexmex

This is after I separated the throttle body from the intake manifold and you will notice two entrances. Thus as in the prior picture most of the oil and gases are going to enter the left side and that is the reason why one part of the intake manifold is cleaner than the other.

aleksg

Thanks for that lexmex much appreciated.