shark13

As many have, I am experiencing issues with loss of oil and smoke coming out tail pipe in the morning. I have read countless threads and wanted to try and understand what is going on. Are the following statements accurate?

Rear valve covers on older RX300's, and RX330's are poorly designed and prone to clogging?
This causes oil loss as oil is sucked into the engine through the PCV valve?
The result of continually low oil levels is that moisture combines with oil to create sludge?
The sludge over time clogs engine passageways causing engine failure?

salimshah

Valve cover issues are attributed to sustained high speed driving and not the smoke in the morning.

Just my opinion ...
Is there a problem with first gen valve cover? No one complained about loss of oil for the first 100k miles or so. Early models had thin drain tubes and if quality oil was not used (replaced often enough) there was oil gel issue. With or without oil gel the the drain down the block is slow and as the rpm goes up more oil is pumped up. With the right bank at an angle the oil level can rise enough to pass through the PCV into the air intake. The dynamics of rate of drain changes over time.
Note: All vehicles do not show this behavior, but some do [for the record my RX did not burn any oil].
In my view folks have reported success have done so as the 3rd ben valve cover is new. Give it 100k miles and they may exhibit the same problem. I have come across a note where a member reported that the baffle has been redesigned in gen3.

Sludge:
I understand the other way. sludge is causing poor drain down and filling up of the cover. root cause -> inferior oil/improper servicing .. all made worse due to thin drain tubes.

Sludge causes inadequate lubrication [blockages and pooling]

Salim

Lexmus

I believe the only new rear valve cover you can buy at this point from Lexus is the 3rd gen. One member tried to save money and bought a used 2nd gen cover from ebay and still had some oil burning issues, so then put in the 3rd gen cover. It is so much labor to replace, a new cover is the only smart way to go.

Regardless of how you got to the point of needing to replace the cover, do it if you plan to keep the vehicle any reasonable length of time and you drive the car on trips using highways/interstates. That way you don't need to worry about quickly running your oil low. If you want to be sure that the cover is the culprit, attach an oil catch can between the PCV and intake return. I used one of these for confirmation.
They are now 1/2 the price of when I bought mine a couple of years ago.

I replaced my cover, and what a world of difference

shark13

Thanks Salim and Lexmus for your thoughts. Just a few add on's to the topic.

My first assumption when I started to see white smoke in the morning was bad valve seals or worn rings. What has surprised me is that a few people here and there on these forums have expressed that in addition to the oil consumption issue being resolved with the 3rd generation valve cover, they've also resolved the burning oil issue. Could they be related?

I replaced my VSS (rear bank) about 5 months ago and noticed improvement in the "morning smoke" but the issue has since returned. How would the VSS be related to car expelling white smoke in the morning and why would a new VSS give temporary relief from the issue?

My experience with removing heads is with Honda Civics. In those cases the smaller passageways Salim referred to were in head, whereas the passageways leading to the crankcase, at the top of the case, were quite large. If I am interested in replacing the rear valve cover is it necessary to replace the head to ensure the small passageways in the RX300 are thoroughly cleaned out. Are the passageways at the top of the crankcase large in the RX300 as they were in my Civic? Can I instead get away with using an engine system cleaner (that operates while the vehicle is running) to resolve the lingering gel(sludge) that exists in the heads?

Thanks,

Marc

Lexmus

Oil consumption = oil burning