dhamiltonx

I have a 2000 RX300 with about 139000 miles and I am getting the knocking when engine starts to strain a little going up an incline. It seems to be getting worst. If I accelerate at a higher speed, it seem to go away. It seems to be at a lower speed when it first starts pulling. Do you think its gas, or carbon deposits. Any chance of a bearing or water pump?

Lexmex

Bearing or water pump would be more likely to also be heard when the car is not up an incline.

Going up a hill or incline, when the engine is under load, and having knocking can happen, especially if you are using lower octane (but no reason to change just on account of a hill). It happens to me, despite using 92 octane, almost new plugs and just about everything else mechanically in shape. My low oxygen content does affect of course the combustion process, but the engine adjusts as best as it can.

I overlook a road on a hill where I live and I can hear cars ping as they go up the hill.

mikey00

Assuming you are using regular, try high octane to see if the problem goes away. You shouldn't have to use high test but this test will at least give an indication of what type of knocking you have. If it goes go away with high test it could be carbon deposits. This is sometimes one of the early indications of oil gelling, might be a good time to check.

Fern

I had knocking for about 6 months regardless of spark plug change and premium high octane fuel.

Eventually a check engine light came on due to lean mixture and the last (after the cat converter) o2 sensor was replaced and problem went away.

I concluded the lean burn was not providing enough fuel to prevent knock.

Knockless ever since.
My car has 93000 miles

Blkongray

What kind of 'knocking' are you hearing? Is it like a 'clammor' of valve train components, or that deep knocking from predetonation? If it's the clammor like it's an odd diesel engine or something, then that's the same thing I have. Initially I attributed it to the fact the 1MZ-FE engine has mechanical lifters and if there gets to be any carbon deposits on the valves, it could create slop in the valve train causing the 'rattle'... but it's a strange noise. Kind of like what Dhamiltonx described. It's a rattle under slight load (not enough I would think to give predetonation or 'pinging'), but with a little snap of the gas pedal the sound goes away. Plus it seems to do it worse when the engine is warm... it's smooth and quiet when cold.

I see some deposits in the valve cover and fill plug when changing oil, so I hope I don't have too much sludge build-up. I'm just starting an Auto-RX cycle, and will repeat when done (since my ride has about 120K on it). Hopefully that will clean it up a bit, then I'll run Rislone in it from there out. We'll see if that clears things up.

I've seen a few sporadic posts on this topic elsewhere, so it seems like this isn't an isolated case. One poster wrote in about multiple reworks/rebuild at the dealer's expense where the sound kept coming back. The dealer finally said it was just 'inherent to their specific vehicle'. Translation: "we don't know what it is."

sktn77a

iTrader: (2)

Pinging (pre-detonation) sounds like small ball bearings rattling around in a glass bottle. If you're hearing "that deep knocking...." you have other, major, problems (probably engine bearings).

Sounds like an oxygen sensor going out, messing up the mixture and casuing pinging. That's what happened to mine.

DDLexus

Mine did the same thing and then I started to see smoke on startup out of the exhaust. I took it into the dealer and it was SLUDGE. Engine was replaced under warranty. After the replacement, the RX ran much smoother and I continued to use 87 octane. Don't fall victim to the 89 or 93 octane game the dealer will play with you. There is obviously something wrong with the engine.

Blkongray

Hmm... interesting. I've never heard of predetonation described as 'small ball bearings rattling around in a glass bottle'. I would think that would be a high-pitched 'clinking' sound. I've always heard predetonation described as a 'knock' or 'muffled rocks in a can'. Either way, it's that distinct sound that one can tell is coming from within the engine underload, but it's not a hard knock like when a bearing surface is wearing.

Anyhow, I found something on the web that seems close to what I'm experiencing; it's described as: "The sound is almost like a clatter sound, only under acceleration, some times even at slight acceleration and cruising at highway speeds. When the engine is still cold, it doesn't ping as much. I've noticed that some cold foggy days, it might ping less."

The culprit that was found (especially in that most cases it's with a higher mileage engine) was "carbon build up in the engine; The build up causes increased compression when the engine is hot, thus the pinging sound. The sound is less upon start up and on cool days because lower engine temp and cooler environment mean cooler air charge temps which help prevent spark knock."

I guess if one had a thick build up of carbon it could increase compression, but then it could also form hot spots after a while causing the fuel to preignite before full compression, thus causing pinging. Long term carbon build up can be an engine killer, so I might try Seafoaming it or just do the graduate fuel treatment to clean the valves/combustion chamber. I've heard shops can run a procedure that will clean the carbon out, and another suggestion was "a teaspoon of tranny fluid down the plug holes works extremely well. Use high grade fluid and run it till its burning clean again. Follow this up with a bottle of concentrated/every 6 months strength combustion chamber cleaner."

I don't know, but on my ride there isn't any smoke out the exhaust, it passed emissions with flying colors, it runs smooth, and the only oddity is this clatter at times. I'll try a few treatments and see what works.

As for Dhamiltonx, if you ever get that knock (and it's a deep knock) at idle, then I'd say it's a rod knock. You can tell a rod knock because it's a very hard knock, not a 'pop', but a thudding knock. If you do have a loose rod (most likely due to a worn bearing), you can make life on it a little easier with Motor Honey or a heavier weight motor oil, but eventually you're going to have to address it. But first, try and rule out everything else... see if the sound is less/gone upon start up and during colder weather. Rod knocks should be most pronounced on start up, since there's a lag as the oiling system comes up to full pressure.

dhamiltonx

This sounds just like what my 2000 RX300 is doing. Mostly always happens during pulls up inclines. If I accelerate harder it seems to go away. Appears to be from slight to medium acceleration. No sounds in neutral an acceleration. I burn low grade. Have not notaiced any smoke. It seems to be louder at times. I guess I need to take it in and have them look at carbon buildup or o2 sensor.
Thanks for your help!

Fern

o.k. folks lets not conclude that all our engines have sludge...

My knocking went away after my last o2 sensor was replaced (located after the cat converter).

I was burning too lean...

Co-incidentally the rear o2 sensor was sending the wrong signal to the front o2 sensor (in the exhaust manifold) and causing it to heat up resulting in a cracked manifold.

Manifold was replaced and the last o2 sensor also replaced and 20,000 miles later still no knocking or pinging or CE light.

The downside is that the o2 sensors from Toyota are rediculously expensive... Even the tech shook his head stating the price of the sensor was a joke.... $280 + CAD for the sensor itself..

I've also got a V8 5 Series Bimmer any the most expensive 02 Sensor is $85.