oldusedone

Owned 2001 rx300 (136K miles) for two weeks, took to son in college. CEL came on after about 300 miles of 75 mph driving. Found oil down three quarts, was full at departure. Added and check engine light stayed on for rest of 200 mile trip and had to add two more quarts. Brought to Lexus dealer and they said #4 cylinder was 20psi should be 120. Is this related to the oil sludge issue talked about here? Car still starts but runs rough with check engine lite on. The pros tell me the engine is ruined and we need a replacement. Can't we just have a five cylinder until my son hopefully graduates, no trips over 3 miles is the recommendation. Why when I was young we didn't need these fancy smooth engines.

Report from dealer "error codes p0300 and p0304, performed cylinder leak down, leaking out the exhaust. Engine has several oil leaks and also has oil in the intake air duct." Dealer offered 1K on a trade in. Tires are brand new as is battery, so they were offering me about 500 for the car.

Also, why would the check oil light not come on even down 3 quarts? Could it be disconnected or is that normal when down so much oil? We are closely monitoring the oil levels every few miles. I'm new to buying used cars on craigslist and was seduced by the smooth ride of the rx300, my mechanic checked it out and said it was a good car from what he could tell. When checked, not burning oil that he could detect and a smooth engine sound. I was the fifth owner, according to carfax, which is a risky gamble, in hind sight I can clearly see.

Thanks,

Sad Dad

AnthonyMtz

They are nice cars you could probably find a used engine with 100-120k for less than 900$

kalali

Sorry to hear about your issue but no, you can't really run on only 5 cylinders for any extended period without damage to a bunch of components including the emission control components in the exhaust system. Get a second opinion and if the rest of the car is solid, invest in a rebuild or a used engine.

oldusedone

That makes sense, the oil must go somewhere and the catalytic converter sounds like where it's going. Since we burned a bunch over the 200 miles of high speed driving we are trying learn what the rate of burnage is at low speed short range driving, until a fix is in place. In other words, his mother will let me live, for now, if he can drive to and from school.

any ideas about the missing check oil light?

I'm guessing if we do get a junkyard engine it will need the timing belt changed, more than likely, but how could you tell if it was changed anyway? I'm a timing belt doubting Thomas and suspect, without having any real facts, that belts could last for 200K in most cars before failures became too high to justify the risk. But that's an entirely different thread.

Nelexus88

If the cylinder leak down test shows low compression and its "leaking out the exhaust" then you have a bad exhaust valve or valve seat. That is likely the cause of the rough running engine at idle and that can be fixed without replacing the engine. Now the oil consumption is likely due to something else like bad piston rings, etc which may require an engine rebuild or replacement.
I would also suggest you shop around at some independent mechanics for repairs or possible engine replacement at a reasonable cost.

The low oil level sensor may be defective or disabled by a previous owner if you are a conspiracy believer.

Good luck and keep us posted on your decision.

hypervish

These cars do not have a low oil light. They have a low oil pressure light, which is why yours didn't light up with 3 quarts low of oil since there was still enough pressure.

Replacing the timing belt on a junkyard engine should be cheap because the engine is already out of the car and the components can be replaced quickly and easily.

fastnoypi

cheapest route to get the RX running would be a used motor. Trying to salvage the motor regardless if the problem is in the head or short block will cost alot in time if you diy or labor from a machine shop.


Good thing with starting with a replacement engine, you can replace the rear valve cover as needed, valve cover gaskets, pcv, and timing components while on an engine stand.
I would not trust the wear items on a used engine no matter how clean it looks. Often they are pressure washed and dressed up with armor all or wd40 to make them look good during a sale.

matts6887

I would agree here. It definitely is not a good ideal to run on 5 cylinders as it can be costly and possibly detrimental l in the end. You definitely should get a second opinion if you are at all in doubt. Just remember; if you invest in a used or rebuilt engine; as some of the others have eluded to; make sure the timing belt, gaskets, etc are all replaced before the engine is put in the vehicle as its obviously less costly to do it while its out of the car as far as rebuilding the engine or getting a used one.

oldusedone

So being down three quarts would not trigger the oil pressure light? When should we expect that light to go on, with 1 or 2 quarts of oil? Is there a way to test to see if that sensor is working without running the engine with much less than the proper oil level? Would this be something that the diagnostic computer would pick up, a faulty oil pressure sensor? Since the dealer did not mention anything I'll assume it was good or does not get picked up with all those error codes if it does go bad?

Currently when oil is up to the top dot on the dip stick it gets down to the lower dot in about 10-12 miles of local driving. It almost seems like the first 3 quarts disappear quickly while the remainder does not vanish nearly as fast. This is not something we want to test out, running for extended miles under the lower dot but just wondering about that.

swengines.com has an engine with 72K miles on it for $2400 or thereabouts. That's more than I'd like to spend but it looks like they run 1800 at best from my quick study.

Thanks for responding

Paul

hypervish

There's no guarantee of how many quarts you have to be down before the light is triggered, again it's an oil pressure light, meaning as long as there is enough oil pressure the light will not be triggered.

I've seen instances in other cars where this light goes on during turns. In one particular example, upon checking the dipstick it was empty. I added nearly 3 &1/2 quarts to it's 4 quart sump.

Checking for a faulty oil pressure sensor is the least of your worries.

I suggest you/your son stops driving it, that's a ridiculous amount of oil loss.

For used engines or any other salvage yard parts check : www.car-part.com

salimshah

The CEL is triggered by mostly emission issues and it is not mother of all diagnostics.

I really think you should change the mechanic who could not see oil leaks as reported by Lexus ... unless some one steam washed the engine bay right before examination.

The oil has to go somewhere. With that much loss the exhaust must be very sooty or you have a leak which should be easy to spot.

We dont know how long the oil has been exiting through the exhaust (assuming that it is), you may have to replace expensive components in the exhaust system.

Have you checked that the instrument cluster warning lights come on when you turn the key to run before moving it over to start. It could be that the oil pressure light is blown,

Salim

jnovak01

My recommendation to you is get the right diagnosis on the cylinder pressure first, then weigh your options.
Please allow me to explain my reasoning and give you another perspective regarding the car.

There are tests you can do to determine if it is a head gasket or piston ring issue. Search youtube or google it. I would get this test done first before making any decisions. The lower pressure in the cylinder is the larger issue and I would encourage you to do a little investigative work here to determine root cause.

The RX’s are prone to have oil sludge build up on the inside of the rear valve cover.
This causes all kinds of issues.
Your symptoms are VERY consistent with this happening. To fix this you need to replace the rear valve cover and replace the PCV valve.

Let’s suppose you have a bad head gasket. Your cost to repair the gasket would be $2000 or so? To do this the back head needs to be taken off the car anyway and you can have the valve cover replaced as well which would most likely eliminate your sludge problem.

I think you have two issues here. One most likely is oil sludge. The other is either a bad vale or head gasket. My money is on the head gasket.

Now, lets weigh the option of repairing the engine vs. replacement.
A repair for a head gasket/valve cover could be say $2000?
A used engine - that may very well have oil sludge issues now or other that you don't know about - $3500?

I think you will be better off with repairing the engine you have rather than rolling the dice on a used one.

jimsRX300

Sorry about your situation, we all want to take care of our kids. Search my username for what happened to my RX300.

Here's a 3rd option. Why not buy a set of used 1mz heads off eBay? 500 bucks! Done. Replace the piston rings while u r at it. Most of that work can be done with the Chiltons / Haynes and Autozone's Alldata.

It's just not worth dumping 3+ grand into it. Believe me, I've done it and wish I junked mine.

jimsRX300

You could get the set machined, but I wouldn't bother. Then run a case of carb cleaner through it. Replace the oil pump & do a timing belt water pump service too.

Oh and a new PCV valve.

I now use BG MOA in every oil change and change the PCV valve every 10K. No oil consumption in 55K miles.

matts6887

I agree with hyper here. I will tell you why. Not this current rx300; but the previous one that i had picked up and only had for one day before it went right back to the lot because it had too many issues with it. That one had something wrong with the oil pressure sensor because it started blinking on and off on me while i was driving; however; when i checked the oil level at the first chance i had; it was still completely full which meant to me something was amiss with the sensor. So in the end; no; the light not coming on; doesnt always mean everything per say.. Believe me that was the least of the problems with that 300; so back it went to the lot it came from.