Lexmus

I have the maintenance records back to 2003 on my RX, and between the second owner and myself, six coils have gone bad. Four of those were OE. I am not sure about the two of the replacements that failed, but they were installed at a Toyota dealer.
When I replace the coils, I use Denso.
I replaced #3 when I did the spark plugs as a preventative maintenance given my coil history.
It is hard to remove the coils #3 and #5 without removing the intake, although I have done it. But if the intake is off I would consider changing them then with a Denso. I understand if you choose not to, just my 2 cents

The front coils #2, 4, and 6 are simple to replace, so no need to proactively change them.

trhs75

Okay -- I have nearly everything apart, and I have removed eight of the nine rear valve cover bolts. Both rear corner bolts are hard to access! I have a gasket and sealer. I saw one post that talks about where to put the sealer -- only on certain spots? Also, with the new PCV valve, does it need to be oriented a particular way? On the old one, the opening points toward the rear. I haven't looked at the new one yet. This is quite the project!!

salimshah

Here the tricks for DIY ,,, Always loosen the hardest-access nut/bolt first .. the rest being inplace, allows the hardest to come out with ease.
Some time moving the things out of the way helps ... in this case the cowl ,,, where the wiper motor is. Yes it means more work, but you work with ease.
PCV-plumbing must be thought of when you position the outlet. So dont work without having all the parts.

Service manual is a great aid.

Salim

trhs75

Thanks, Salim! Cowl is out; I don't know how anyone does this without removing it. With the intake manifold moved out of the way, I can't yet see how things will line up with the PCV valve; I'll look as I start reassembling. The rubber hose position may show me the natural placement position for the PCV valve. I have the valve and all the other parts. Also, I plan to buy some extra hardware in case something drops!

Lexmus

trhs75,

Not sure what you are referring to about the PCV valve orientation. The metal PCV valve is straight as opposed to the plastic valve which has the 90 degree bend.

trhs75

Ah, thank you! If I'd opened the box I'd know that. I just assumed it was bent like the original. It really wasn't a very educated question as I think about it.

Puttster

If you get under there with a flashlight you might see oil drip lines coming down the rear of the block. Before doing anything drastic, clean it up and gob some sealer along the valve cover line. Save your energy for changing the rear plugs.

trhs75

Well, I got the rear valve cover and gasket changed out (along with the PCV valve, of course). While I was back there, I changed the three rear spark plugs and ignition coils. I had changed plugs and coils on our other '99 with the throttle body and intake in place, and they're a LOT harder to change that way. As I looked into the engine after removing the intake manifold, I could see that the three rear intakes looked much darker and "oilier" than the front three, bolstering support for the rear valve cover being the problem rather than the piston rings in one cylinder causing the oil usage. That's my hope, anyway! This was probably the most complicated thing I've attempted on a car, although not physically as difficult as changing the four struts on my daughter's Olds Intrigue. Some of the valve cover bolts were difficult for me to access to loosen and to retighten, and I'd swear a couple of them seemed loose already when I started removing them. Everything is back together, and I've been making notes about the process to help me in case I ever have to tackle this again. Ugh. The car runs like a top; I'm keeping my fingers crossed that I've solved the oil loss problem. I appreciate everyone's input and advice - I'll provide an update when I have one!

owenstrawn

Congratulations trhs75!

I did the same thing today - except I didn't replace my spark plugs. 3 hrs to disassemble, 4.5 hrs to reassemble. The heat and exhaustion really slowed me down after noon (I was outside in the driveway with no shade). Discovered a coil gasket on the ground when I went to retrieve a dropped intake chamber nut, so I had to back up a little bit (forgot to reattach the PCV afterwards and retighten the ground nut but those showed up readily enough when I started the engine). Also when I was remounting the wiper arms I realized I had omitted the wiper harness and had to back up again.

The hardest part for me was disconnecting the curbside rear lower connector (Bank 1 A/F sensor?) and the streetside connector under the head (power steering switch?) to get the harness out of the way. And then getting them back together afterwards without being able to see them. When you finally hear that click, it's like a choir of angels...

My rear manifold hangers were loose at the bottom; the dealer service guy must've done that deliberately because it sure made it easier to get the upper nuts off. A wobble socket would've helped a lot with reinstalling the one on the back of the intake chamber assy - I ended up leaving it loose because my triceps started cramping. I could not get the semi-circular plug out to repack it. If I have any leaks that will be where they show up first. I had to double-nut to get the middle mounting stud loose from the decorative engine cover (fortunately I had exactly one metric nut that fit in my collection). I used a 6mm socket to easily pop out the weatherstrip clips under the wiper tray , and 10mm for the wiper harness clips IIRC.

The 1/4" HF torque wrench worked great but the 1/2" was useless because I apparently have no 1/2" sockets! The $20 HF passthru socket set was again a lifesaver. HF star socket set worked a treat as well. Menards 20V drill/driver with a 3/8" socket adapter was helpful for spinning the longer bolts off & on too.

I took some of the slack out of the cruise control cable while I was reattaching it. Not sure if I should've done that...

trhs75

Great job, Owen! I picked up that Harbor Freight pass-through socket set, as well. You're right -- what a great help it was! Hopefully, I won't have to do this again and I'll never need to use all the notes I made!

owenstrawn

12 miles to work this am (mostly freeway) with no CEL or unusual noises or smells. So far so good!

trhs75

Yes, I was relieved not to see an oil slick forming behind the car as I drove it after its "surgery." I need to make a highway trip (100+ miles or so) so I can assess the oil usage.

Dukenukemx

I did this, and it did make a difference in oil consumption. I also painted the valve covers red cause as we all know red makes things go faster. I painted it with Eastwood paint. It did take me forever to clean the carbon off the valve covers but it was worth it, plus I changed the valve cover seals, PCV, and spark plugs. It still eats oil but very slowly now. I used gasoline and a wire brush to do the cleaning.

salimshah

Let me understand this bit better ..
when you say you did "this" ... do you mean you took the first gen valve cover and cleaned it up and and put it back and this reduced the oil consumption?

Salim

trhs75

That's what it sounds like to me also, Salim. I have wondered if cleaning a V1 valve cover would help the problem, but I agree with fastnoypi that it seems simpler (although at a $200+ cost) to just put a new valve cover on instead.