tllee

I had the same idea as yours at the beginning. Trust me, if I have a solution which cost less money, I'll go for it.

1. clogged oil passage: I used my air gun shoot air through the front PCV inlet(take off PCV valve), I can feel the steady air(little pressure feel) come out of PCV valve screw-in hole. That's mean those passages could relatively OK. Then I removed my valve covers, I used a long ,thin plastic stick(it is very sturdy built, not easy to broken off) poke thru some large passage holes, I can reach the oil pan. Even some small passages clogged, the large main oil passages will guide the oil down. So I tried second theory.

2. stuck piston rings: I got an engine compression gauge, I test every cylinder(yes, including the rear 3s), all are within parameter. BTW, I bought this car new, I changed oil every 3000 miles or less, only had 2 times that I changed my oil at 5000 miles+(I used synthetic oil at that moment). I'll say that my chance have a "dirty" engine or clogged passage is very small.

So I came to the final solution that suggested by a lot of Toyota forum and this forum, "change the rear valve cover". When I took it off, it's not that dirty as shown by some owners but inside the baffle plate contain a lot of "stuck material"(inside of baffle plate contain a "felt-like" material, I think it's the major cause for this oil consumption). The splashed oil and some condensed blow-by take too long to flow back to upper side of engine and it sucked up by PCV, but from upper side to oil pan is no problem. The "material" is not expanded when it was new and not have a lot of miles on it, but when it aged, it expanded and crumble a bit. I think that every owner of this car should know see "weird" stuff on the baffle plate when they open the oil filler cap.

MY ONLY "FAULT" IS DROVE THIS CAR ON SHORT TRIPS(LESS THAN 2 MILES) FOR SO MANY TIMES OVER 3-4 YEARS PERIOD. IF YOU CAN CALL IT A "FAULT". SO IF YOUR DRIVING PATTERN IS NOT LIKE MINE, DON'T WORRY ABOUT THIS PROBLEM,YOU PROBABLY WILL NEVER ENCOUNTER ONE.

Spend money and time on this issue is pain in the ***. If it's our maintenance problem, fine , we'll suck it up. BUT, IT IS NOT. So I am mad about Toyota's ignorance of their customers(check Toyota forum, you'll surprisingly find there are so many discussions about this matter) Hey, if you send this car to garage for this kind of repair, it will cost you a lot money and probably still fooling around without solution. Fortunately or unfortunately? some of us can do it ourselves.

fastnoypi

Just out of curiosity, do you recall approximately on the bottom of each head where the larger oil passages are located? I've been looking for any pictures of the heads without their cams to identify.
I don't think they are the problem in my case because the heads were pretty drained of oil when i opened up the valve covers. No puddling what so ever.

I am still in observation with any oil consumption right now. I have a feeling since i changed out the rear valve cover, my sister did not read the dipstick correctly when she panicked over an unrelated CEL a couple weeks back and inadvertently overfilled. (my fault, i think i forgot to torque a ground nut tight enough)

At this moment, i'm confident that everything engine wise is up to spec including compression. Our RX is getting pretty good gas milage considering.
It also has a history of very short trips 2-4 miles daily over several years.

tllee

I borrow someone's picture , please see the red circle area, there is the biggest passage. Hope this will give you the idea, there are some small passages under camshafts that all seem OK(no clog)

fastnoypi

thanks for the pics. I had a hunch it is somewhere in that low lying area opposite of the vvt gears.

Gmachine

What is strange to me is that my RX330 has what is pictured as a RX300 valve cover & baffle set up! I was just going to clean it, but now I'm wondering if I shouldn't upgrade it with the newer baffle. I know my car is an 04 so maybe they used left over valve covers?

fastnoypi

very strange indeed, however Lexus did go through 2 different iterations of valve covers in the 1st generation RX. It is very possible the production line stopped using the "late 1st gen" valve covers up to 2004 and decided to upgrade to its latest design from 2005-2007.

I no longer have oil consumption issues after 10k of driving after upgrading the valve cover.
If you do not have oil consumption issues, i would leave it alone. The swap cost me under 200 in parts(cover and gasket set) and alot less time had i pulled my old valve cover for a thorough cleaning.
It definitely won't break the bank if you do decide to upgrade for piece of mind.

Gmachine

Yes, I have small puddles of oil around the throttle body, but not in front of it, so the rear VC is suspect. My main issue is I have a P0420 & P0430 CEL. I've removed the front catalytic converter & soaked it in dish detergent, it's not busted up & my sensors are working properly. My guess is the oil is making its way to combustion & causing a problem. If this fixes it my wife will be very happy. It's 160k miles

Drcoffee

I was surfing ebay and found the new valve cover used. From the picture, it clearly looks like even the new baffle design has sludging issues. Note the area by the cam gear. I still plan to change my right cover, but as an ounce of prevention, add a quart of MMO to the oil and hopefully over time, keep the oil passages clean.

Actually, as I look at it closer, this is more troubling than the 2004 version with the screw in pcv




Using a synthetic or semi syn oil is probably a good choice to minimize oil coking.

Has anyone tried or considered just running it old school with a breather vent and plug the pvc intake port? Ingesting oil lowers the fuels octane rating.

salimshah

Try the catch can

Salim

fastnoypi

IMO, that valve cover looks like the previous owner did not change his oil per maintenance schedule. My 2nd generation cover had alot less burnt oil sticking to the surfaces. Its not the baffle design of that 3rd gen problem that caused the sludging issue. I have pictures somewhere on the forum comparing the 2nd and 3rd generation covers. The baffle breathers are shielded off to the side to prevent direct oil slinging from the cams on the 3rd gen as compared to 2nd gen design.

+1 on using a catch can if you are ingesting oil or preventative maintenance on a failing pcv, it has an advantage over using a breather because of the vacuum effect pulling any residual oil inside the baffle that would otherwise gel and clog the valve cover.

Drcoffee

I believe your supposition is incorrect on the flow of oil out through the pcv. I dont believe the oil is a flowing pond of oil that reaches the pcv valve. Why? Because if you had liquid oil flowing into the intake, cylinders 1&2 would be coked or hydrolocked. I believe we are simply talking about vaporized oil being inhaled too fast by the pcv. The crankcase is churning up the oil and aerosolizing it where it then rises up through the large passages to heads and sucked out via the pcv. The baffle is supposed to restrict the slung oil and it probably does a good job of it. The aerosolized oil however flows freely under the strong vacuum of decelleration. So the question is how can you stop it from reaching the intake?

Has anyone considered the possibility that the hose from the PCV valve is too short. Its only about 4" long before it goes into the intake. My thought on this is the hose is only 3/8" dia. The volume of air passing thru it under vacuum is significant. The vaporized oil coming from the valve cover never has a chance to condense and drain back. What if the hose had a larger diameter and longer run to allow the vapors to slow down and condense on the hose? I was looking at the intake and if the pcv hose was about 12" long and 1/2" ID brought forward and wrapped around the front shock cross brace and then back to the intake. Or increasing the length and installing a fuel filter inline to screen out the vapors and liquid oil before entering the intake.

The vacuum is at its strongest under decelleration. Otherwise, there is low air flow during acceleration and the oil can drain back down the hose into the valve cover.

Just thinking outside the box looking for a simple solution other than a oil catch can. I am opposed to the catch can idea, since those who have serious oil consuption can fill the catch can in under 1000 miles. Then what? A huge slug of liquid oil would be ingested if the can is not emptied. It would be great if there was a way to recycle most of the oil back to the engine.

fastnoypi

If you really want to avoid oil ingestion and be maintenance free use a oil scavenger bung on your exhaust and plug your intake manifold connection. Under acceleration it creates a light enough vacuum to pull oil vapor from your valve cover. The residual oil burns in your exhaust. Its a old school trick on the track if you dont want to spend on a pricy dedicated vacuum system. http://vibrantperformance.com/catalo...oducts_id=1243

An oil catch can with a sight is the way to go. It will tell you right away if your valve cover baffle is gelled up or pcv stuck open. Dump it when fills up, then troubleshoot your problem.

salimshah

DrCoffee, read through the thread and you will see evidence pointed out by Fast and others. To be open minded, if any one who disagrees with oil traveling up the PCV path should put a catch-can and verify. Since my RX does not exhibit the problem, the test can not be performed by me.

Replacement of valve cover has helped many who have done the swap.

If we were to be scientific about it, we should have replaced some with a fresh '99 valve cover and then compared .. but that is not going to happen.

There is yet another possibility that the oil is not draining fast enough, while it is being pumped up at faster rate.

Salim

Drcoffee

I have only owned mine for 100 miles and two weeks. Im in the process of replacing a bunch of wear items before I hit the street with it. So I dont know if it even applies to my rx300. I am just trying to continue the discussion in a way other members can solve their oil loss issue. I just hope mine isnt one of them.

Drcoffee

I can see what happened with the gen1 valve cover baffle and why it ingests oil in liquid form. We can easily see that the engine has a tilt toward the rear and at highway speeds is pumping a lot of oil up to the heads. I can envision the oil ponding in the lateral aspect of the cylinder head right up to the baffle itself and covering the lower vents (green arrows). At low loads, the vacuum is light and can easily suck the volume of air in the small vent at the top (yellow arrow), but when the engine is at higher rpms, the small top vent cant flow enough air to feed the demands of the PCV line. The oil ponding below has covered the two larger vents/drain-backs and the vacuum then draws the oil up under baffle and right into the PCV valve. see the yellow arrow is the only place for the PCV to draw from if the oil is covering the lower two vents. Its like sticking a soda straw into the valve cover. Makes perfect sense now why it only sucks oil at high rpms.





Whereas the Gen2 valve cover reverses the vents and makes the drain backs smaller (mistake IMO) and enlarges the upper two vents to supply the PCV with oil free air. The lower vents are still bathed in the oil but the upper vent can handle the PCV volume of air at higher rpms. I don't think the slung oil is really the issue unless the vacuum is so strong it draws the oil up under the baffle. I think the Gen2 and Gen3 are better suited to screen out the oil. The PCV valve is in the upper left corner of the baffle.