jdog1031

Purchased a 2000 RX 300 with about 140,000 mi in 2/2016 in a town a couple hundred miles from where I live. About 2 weeks after getting it home, it started blowing blue smoke out it's tale pipe on start-up, especially when cold. Using significant oil (about 1-2 quarts per tank of gas), with no leak on the ground.
The lot we purchased it from has a 50/50 warranty (you split the repair cost) and he was tossing around a figure of about $5,000 to start tearing into the engine from the top down and his warranty requires that HE do the repair.
Wanting to go into the repair with some knowledge, I took the car to my local Lexus dealer and had them attempt to diagnose the issue. They indicated I have a bad Base Seal (Part # 90080-31053).
I also have a knock sensor issue, which started about 3 months into my ownership (I've already done research that), and am planning to have both replaced at the same time.

Lexus quote was just under $4,000 to do the work on the seal and knock sensors.

I have 2 questions as I am dealing with a used car dealer I no longer have faith or trust in (why I did to start I'm not sure) and I want to make sure we do this repair once and get it right.
1. Would this bad Base Seal account for the oil burning through the engine?
2. Would the oil burning through the engine cause the knock sensor(s) to go bad?

Thanks in advance for any help you can provide!!

fastnoypi

welcome. The bad "base"seal part looks like a rear main seal. If they are one in the same, the seal would not cause blue smoke, just a big mess on your driveway.

Since you have a early 1st gen RX, i would suspect your rear valve cover to be the culprit in your oil consumption. Many of us have gone the way to resolve the problem by upgrading to the RX330 rear valve cover due to is redesigned baffle. It's a "cheap" fix if you DIY.

Oil introduced into the combustion process can increase knock count by decreasing octane in the air/fuel mixture, it is possible over a long duration of oil consumption and driving the knock sensors could get damaged.

salimshah

Welcome to CL.

Please visit the dealership which diagnosed bad seal and tell them that you have oil consumption issue and see if they can validate that. What I am saying is that the repair request should no the for the seal ,,, it should be for oil consumption out of the tail pipe.

Salim

Drcoffee

Here. Read up and dont get hosed by the stealership.

https://www.clublexus.com/forums/rx-...e-cover-6.html

jdog1031

Thanks for the quick response guys.
@Fastnoypi - I was assuming the "base" seal was a main seal also, but when I typed in the part number
that's the label they put on it. I didn't think a main seal would cause oil burning issues, but once you get to internal engine items, you quickly lose me. I do the basic DIY stuff, (starters, alternators, brakes and an occasional water pump, etc.).

I copied the URL of a drawing of the part # they provided and where it fits in the schematic. It's part #8 on the diagram. Does that say main seal to you, or are we talking something else?

http://cdn3.volusion.com/nuwav.yteth...8908155-2T.jpg

The rear valve cover issue does make a lot of sense, especially since it's ongoing issue with the vehicle.
Will replacing the rear valve cover lead me (eventually) to the main seal if I keep digging
in the engine (i.e. is this one big job or two smaller ones)?

Drcoffee

#8 is the front main seal. If they do that one, get the timing belt and water pump done at the same time.

salimshah

Guys:

There are a lot reasons to burn oil. Oil through the intake should be verified by a catch-can. There are many RX on road with no oil burning issue through the intake or rings. Just dont blindly follow something that work for some members.

Once again, my suggestion to OP was take the problem to the mechanic and not a solution. If the shop does what you want and if the problem is not solved, they should not be held responsible. Watch out when the shop comes back and says they can try 1, 2, 3 ... till the problem is solve .. in this scenario they keep charging for each step.

Salim

fastnoypi

Drcoffee beat me to the reply.

The rear valve cover is not that bad a job. IMO you are qualified if you have replaced a waterpump. While doing your rear valve cover, it would be a great time to replace your rear sparkplugs and F/R valve cover gaskets while the intake manifold is off and any misc hoses that show wear.

Lexmus

If I was changing the knock sensor, I would change the rear valve cover at the same time since the upper manifold will be removed.

Drcoffee

Salim,

The simple fact is mechanic are not all knowing sentient beings. Most were lucky to graduate from high school. They guess until they get lucky or you give up. At $140/hr plus parts, I can guess for a long time before equalling what the stealership would charge me. I have never found a mechanic who will give a set price and then keep working on a problem until its solve. They will charge and charge for every guess they make. Is it an educated guess? Yes, it could be called that. But its still a guess all the same.

If the OP were to change the valve cover and spend $200 in parts and a day tinkering he might avoid the obligatory mechanic statement " its your piston rings and we need to tear down your engine". If it doesnt solve the problem, then he is only out $200 and some time. Whereas, if he starts at the stealership, he is into it for $200 just for shaking hands. Granted he might get a free cup of lousy coffee but thats no consolation. I avoid the dealership mechanics like the plague and independant shops even more. But thats just me.

We know that gen1 RX300s have an oil ingestion problem. So much so they redesigned the valve cover. He is losing oil. 1+1=2 Could it be something else? Sure. But why look for zebras when horses are indigenous to your area. Lets look at it this way. If its something really bad, how much do you really want to spend on it. There is no guarrantee that the mechanic will fix it and thats going to cost you $1,000 plus to figure that out.

Just sayin

And Im not certain that the knock sensors are bad. Fixing the oil ingestion might just fix the abused knock sensors once half of what you are burning isn't oil anymore.

salimshah

I hear you DrCoffee.

Basis of diagnosis has to be first based on evidence and preferably verified by testing. Oil through intake can be verified quickly by adding a catch-can.

Human psyche is to do the least in the hope of achieving the objective and they get sucked in by mechanics. staying on topic ... I would encourage OP to ask he mechanic/shop as to what evidence they have that links the problem to the diagnosis.

Problem Oil being lost/consumed
1. Drained off .. oil leak .. visual ... vicinity -> seal/gasket
2. Consumed .. smoke ... testing --> catch-can/compression

Talking about opinions ... I have one too about oil consumption .. mine is that it is a maintenance issue, jut like oil gelling, it is rooted in the thinner drain lines. If you eliminate a few in production line, most of the RX when new did not have oil consumption issue. As the RX aged some developed engine gelling and some developed oil through the air-intake. As always, is my opinion right? Even I am not sure

Salim

Lexmus

I agree with Dr Coffee for his reasoning as well as the anecdotal data on these boards. I can't remember seeing one post here where someone replaced the rear valve cover in response to oil consumption issues and did not see marked improvement in oil consumption. (Salim probably will find one or more to disprove my statement) It is true there could be many folks who did the valve cover change and it did nothing and chose not to report that fact. But I expect some negative results would have been posted here regarding the valve cover change if it wasn't the major root cause of oil consumption problems with the RX300, especially if they did the change as a result of reading the success stories in the threads.

salimshah

I will try once more to make my position clear and then hold my peace.

If you have an oil burning issue, please verify that it is through the intake.

I agree that there is anecdotal evidence that folks who have switched to the newer valve cover they have reported reduced/no oil burn.


Salim

hypervish

+1, I agree with Salim.

Not every RX has had an issue with oil consumption. My RX with nearly 240k miles has no oil consumption issues with the original valve cover, and that includes high speed driving on road trips.

Why throw parts at the car if it won't solve the problem? Spend the $200 on proper diagnosis.

Boypony

Compression check. It's either rings, valve seals, or valve cover. Gen 3 cover fixed my oil sucker.