dwg2116

I just replaced the front and rear valve cover gaskets on my 2005 RX-330. with 250,000 miles. They were weeping oil down the front and back of the block, and causing drips in the driveway.

When I had the valve covers off, I was shocked to see how much crud there was accumulated inside the covers, and caked on the heads, I have never seen this much sludge on any vehicle in my life. Particularly the forward head. While I had it open, I cleaned the covers very well, and cleaned as much as I possible could off the internals of the heads. I plugged the dropdown area where oil drains back down into the block with rags, and scraped and vacuumed up all the sludge and debris I think that little or nothing from the cleaning dropped down into the oilpan. What a mess. From reading here now, I see that this is a known problem with some Lexus engines, but I had never heard of it before.

After reassembly, . which included new PCV valve and cleaning out the vent lines, The car started right up, and seems fine.

HOWEVER, when I was test driving it, after ten minutes or so, the oil light came on and stayed on. I immediately shut it down and pulled over, checked the oil level, which was fine, looked for leaks, there were none.. I restarted the car, and the oil light along with the other warning lights briefly lit, and immediately went out when the engine started, as normal.

a few minutes later, the oil light came on again. I immediately shut it down, double checked oil level, and then restarted, Light went out and has stayed out for the drive home.

I have never, ever seen the oil light come on while driving before. Nothing I did, as far as recent working should have affected the oil pump, pressure or oil level, and as I said, I scraped and cleaned the sludge using blockoff rags and a vacuum, so I don't think any dislodged sludge made it down into the oilpan where the pump screen could grab it. Of course, whatever is already down there is still there.

I am speculating that during my wrestling match with the wiring harness while pulling the valve covers, I might have broken or dislodged the oil pressure sensor wire.

Can anyone tell me where to find the oil pressure sensor on an RX-330? I'd like to verify with a test gauge that I really do still have good oil pressure before I look into anything else...
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LeX2K

Oil pressure sensor for the idiot light is above the harmonic balancer these are almost guaranteed to leak eventually. Too lazy to check if your car has an oil level sensor if so it's on the side of the oil pan.

iMSQ

Try to change oil and filter....

dwg2116

To close the loop on this issue, if anyone is interested, and thank you to those who responded.

Because, as Lex2K said, the oil pressure sensor is down by the harmonic Balancer, which is nowhere near where I was wrestling with the wiring harness, I do not believe I dislodged or damaged any wiring. Therefore, I believe the idiot light indicated that I really did have a low oil pressure issue.

I dropped the oilpan and oil pickup for inspection. Although the valve cover/cams/pcv/vent lines were very sludged up and crusty, the oilpan, and what I can see of the lower engine is not too bad, all light tan in color, with a thin, hard buildup in the bottom of the pan itself.
The screen in the pickup was about 50% blocked with a hard, crusty buildup, but when I blew through it, there was no resistance. Now, of course a quick breath of air is different than oil, but still, I am confused about why I had those occasions when I saw the oil light come on.

Bottom line, I cleaned the whole oil pan, oil pickup squeaky clean, reassembled and I now have instant oil pressure, and no oil light coming on after the engine is running. I have driven several hours since then so I am going to declare this a Success.

Just speculating, I suppose that maybe a sludge clod from inside the valve cover did make it down to the oil pickup, where it temporarily plugged it, until it dissolve in the hot oil. Although, I was very conscious of trying to prevent that. Anyway, I will take a win any way I can, whether I understand it or not. Thank you all for your help.

Margate330

Nice job and thank you for posting your fix!
The oil sensor measures oil level and that makes sense that your oil pickup was sludged.
I bought my car sludge free but previous owner did 5k mile oil changes documented and I been running Mobil 1 synthetic every 3k to clean up whatever may be there and my engine is spotless clean under the valve covers and my oil pickup screen was mint when I pulled the oil pan.

Even with this I developed a lifter tick and a lower engine tick at 150k miles and cured it with a Seafoam Oil Treatment 2x double strength and did the treatment two times so even with a perfectly maintained engine it can starve for oil in the tinyest places as shown by my testimony.

Add- can I just say couldn't Lexus have given us a proper oil pressure sensor like they did on other models so we can read the pressure with any scanner, why couldn't they do this for us?