owenstrawn

Wait, are you saying compression & leakdown tests won't tell if my rings are bad?

I don't want to hijack trhs75's thread, my situation is described under the "High Speed Oil Consumption" thread.
Thanks,
Owen

trhs75

I really appreciate the advice from all of you -- thank you! Owen, feel free to let this thread lead wherever it goes! Salim, I guess my thinking is that if compression is bad in one cylinder, I may not invest the effort in replacing the rear valve cover, but I'm not sure. It has about 80,000 miles and has been well maintained, so I'm hopeful the piston rings are okay. An engine rebuild (which I'm not capable of myself!) would likely exceed the value of the car. I have changed plugs and ignition coils on an RX before without removing the intake manifold, so I imagine I can get back there to test the compression. It's a challenge, but it's do-able!!

Lexmus

I did the compression test followed by the catch can and based on the results was confident that my oil burning would be cured with the valve cover change, and that the engine appeared to be in good shape.

salimshah

If you have oil consumption at high speed ... put a catch-can [simple plumbing job] and can be a permanent solution if you devise a way to drain and reuse oil. Once confirmed then you go down the option of changing valve cover or cleaning the old one out etc.

Salim

fastnoypi

compression & leakdown tests will give you indirect evidence that something is wrong with your rings and/or your valves. If you are troubleshooting oil loss, take the easiest method to determine where the oil is leaving...as mentioned , that would be setting up a catch can.

Have you had any CELs related to misfire and/or engine shakiness?

owenstrawn

No, my RX idles fine and drives like a dream. And she can go 2400 miles or more without burning any oil at all - as long as I don't drive over 60 mph. But on our most recent 600 mile trip she burned 9 qts of oil, and the mileage dropped by 2-3 mpg. I told my wife "this has been an awesome car but this is her very last road trip".

Also, I have never seen any blue smoke or oil on the driveway - so I'm 95% convinced it is the PCV. But my ex-mechanic friend started ragging on me about "internet PCV theories" and pushed me to do a compression test. And at 220k I'm a bit worried that the engine might be wearing out (FWIW I've never actually driven a car past 150k before). Adding a catch can would definitively tell me if I have a PCV problem, but wouldn't tell me if I also have a wear problem.

Catch can to recycle as a permanent solution is kind of a genius idea, but I'd rather spend the money to actually fix the problem, or to get a rental, or just replace the car. Having to check the oil at every gas stop turns a road trip into a total drag.

fastnoypi

if it idles and drives like a dream, you don't have a wear problem. IIRC from one of your threads you have a 2000 RX, they are equipped with the 1st version rear valve cover with the plastic pcv elbow....earliest and worst design that can get the baffles clogged overtime.

To fix the problem, you will need to replace your rear valve cover with a v3 valve cover as found in the RX330 . No point in getting a later model v2 valve cover in the late revision RX300, it will clog overtime.
If you are bent on figuring out if you have a wear problem, you can do your compression/leak down test when the intake manifold is off. At 220k miles, ..even if you are not convinced an upgrade in the rear valve cover, your RX is old enough to have a deteriorated valve cover seals and spark plug seals and a good time to do your spark plugs.

owenstrawn

Yes, 2000 RX300 AWD that I've had since 60k/2005 with all/same dealer service from new*. They have replaced the VC gaskets and cam seals at least once, and the plugs at 120k. I'm at 220k now and the 11201-0A060 valve cover should be delivered tomorrow (from oemlexusparts in Knoxville). I figure if I can manage the VC install myself, then I shouldn't have any problem replacing the plugs at 240k - or I might just wait until I actually need them.

*Except that I replaced the rear streetside door lock actuator motor myself, also the front brakes, liftgate struts, front A/F sensor, five headlight assemblies, front and rear marker lights, starter solenoid contacts, and rear strut assemblies and stabilizer links.

trhs75

I thought I entered this reply, but apparently not! Owen, I'll be interested to hear your progress. I have a valve cover, gasket, bolts, sealant, ignition coils, and spark plugs all sitting in the garage calling my name. I think I'll replace the coils and plugs while I'm back there; I've had one front coil go bad so far. I'll keep the other working ones for now as emergency spares and give a couple to my daughter for hers. Good luck, and keep us posted!

salimshah

I think you are on the right track. Just make sure you get the PCV for the 3rd gen [or which ever version you plan to install] and potentially the hose as well [the first gen PCV and its plumbing are different].
For long trips, I always rent from national chain. Only once there was an issue with a vehicle, and all we had to do was call-in and the replacement was delivered in an hour. Had it been my vehicle, the vacation would have been ruined. I think of it as "insurance" for a stress free vacation. Lots of miles dont get added as well. When I come back, I appreciate my vehicle a lot.

Salim

owenstrawn

We were actually planning to rent for the upcoming trip, but then decided to spend the money on fixing the RX instead of giving it to Avis. Besides, the whole reason we chose a used RX over a new Camry (or anything else) back in 2005 was specifically for more comfortable road trips. The last time we rented for a trip, the seats were so uncomfortable my wife had to get physical therapy after we returned. That Chrysler's 600 mile range was awesome though.

Lexmus

owenstrong,

If you are planning to change the spark plugs in that few miles, I would go ahead and do them when doing the rear valve cover.

Have you had any ignition coils go bad? I would also consider proactively changing coils #3 and #5 with Denso.

owenstrawn

Never had any coil problems AFAIK. Preventive maintenance plug replacement isn't due for another two years for my usual mileage.

owenstrawn

Are the coils a preventative maintenance item? Would the 120k dealer service have replaced them along with the plugs? I'd look up the paperwork but it has been seven years and I'n not sure which pile it is under at this point.

salimshah

Simple answer is NO. But based on each person's personal experience you will get a different answer. I had only 1 pack go out in 1/4 million miles and that happened after I replaced my plugs.

Salim