SUL4589

I have a 2008 LS460 with 115K miles on it. Noticed a knocking sound coming from front drivers side of the engine. The knock shows up when the engine is started cold and the fast idle drops out. After 3-5 min the sound drops way down, when it is making the noise it sounds like an air conditioner compressor cycling. It is not the air.
Took it to the dealer and had the engine tech listen to the noise..he said he had not seen this problem before and was not sure what it might be. Something internal could cost 800.00 to 5,000.00. I just drove the car on a 1,400 mile trip no issues other than the loud rattle when engine is first started cold. Not sure what to do next. Is this something the factory would help out with if its major?
I get no engine check lights or performance issues.

norviewguy

I feel like some light engine chatter is normal at cold start until the oil circulates to all the moving parts. Have u checked your oil level?

Doublebase

So is it a knock or a rattle? Either way it shouldn't be lasting for 3-5 minutes. I've heard a slight rattle out of my engine on a couple occasions, but it only lasts for a few seconds (if that). And usually it's after I drain the oil and fill. I have heard it before though, I attribute it to the oil needing a second to get up to the valve train or perhaps a little piston slap before the oil has a chance to coat them.

SUL4589

Oil level good. Lexus tech did not feel it was caused by lifter getting oil. It is a metallic knock that cycles like the clutch of an Air Conditioner compressor. One thing I have been told is it could be the cam phaser ( that's the 5,000.00) fix. If that's the case I think I need to appeal to the factory.
You can hear the faint sound after the 3-5 min time frame

wakebord99

I have the exact same sound from my car which is a 09' AWD with 135k miles at cold start. It is very noticeable and can be heard from 20ft away from the car. I just checked my oil today and have lost well over 2 qts of oil in the last 5k miles and now the oil doesn't even show on the dip stick.

I'm going to fill the oil back up to the high mark and report back if this resolved my issue.

SUL4589

Thanks for the reply. Guess I am going back to the dealer today and visit with them. Going to leave the car over night so they can hear the sound from a cold start. My oil level has been and is fine.
I am also going to get an exact price on a cam phaser replacement

Lexuslsguy

Don't forget, up to 90% of engine wear happens at these cold starts. Hearing any kind of flow related noise is sign. Sometimes timing belt and chain tensioners can be the culprit. I would do an engine flush and run better synthetic oil. Carbon building slowing oil flow is also an issue. This is why I would flush the system. Another way would be to replace a quart of oil with Marvel Mystery. This worked well on my LS430 that developed little vale noise on cold starts. Ran it for about 3k miles and changed the oil and cleared it up right away.

SUL4589

Had a nice visit with the service manager at my local Lexus dealer yesterday. I asked if I was to leave the car overnight so the tech could hear the knock from a cold start. We concluded I could but it would not gain much in the diagnostic process. So I asked the approx. cost to replace the cam phaser any sensor/solenoid. He looked up the labor hours which came in at 2,000 to 3,000 with out parts. The parts guess would add another 1,000. I told him it was not a good idea to spend that much on a car with a value of 13k. He suggested I add an engine oil additive and see what happens, which I have done. I took a 2 hour drive to allow it mix. This morning started it cold the knock was quite a bit less but still there, after the engine kicks off of fast idle and then goes away.
I will see what happens. Either (hope) it improves or get a different car.

droclex

Curious..which engine oil additive did you choose? Thanks and good luck with your efforts!

Doublebase

$4,000 for cam phasers?? Yeah I'd try that oil additive a couple more times, if that doesn't work I'd trade the car in.

If everything else fails you could always live with it and see how much you can get out of it...as annoying as it may sound I've known many people with many cars that have done the same. Know a guy who has driven his BMW over 100,000 miles with cam phaser noise...he's got misfires and a check engine light. When I ask him how it's running he says...great. After he gets the thing over 10 mph it runs fine (not an ideal situation for sure, but I see this stuff all the time).

SUL4589

Update: I added one quart of Lucas Pure Synthetic and drove 2 hours. Next morning I would say a 40% reduction in noise. I noticed Lucas recommends one quart for every 4 quarts of oil. This morning took an additional quart out of my car and added a second quart of Lucas. Taking a long drive next week, I will report back .
Note: My local mechanic has removed oil for me so as not to over fill the oil

sktn77a

iTrader: (2)

Not sure what a "Cam Phaser" is? The IS 250 has a know problem with noisy cam gears. There was a TSB for this but Lexus will only fix it under the original factory warranty (not extended warranty). Is this the same problem?

wakebord99

I recorded my cold start knocking sound. Can you let me know if this is the same noise as yours?

I added 2 qts of oil till it was right at the high mark no difference at all. This sound happens 30% of cold starts

SUL4589

Noise seems to show up the most after the car has sat over night. In the morning when you start the car first thing and after the engine drops off of fast idle you will start to hear a knocking sound that cycles much like an A/C compressor. This lasts 3 to 4 minutes. After that the sound drops way off, but once you hear it you can still hear it.
Very faint the rest of the day.
Now that I have added the oil additive the last 2 days no more noise even after night. I have my fingers crossed this may be the answer. Taking the 460 on a road trip next week and we will see how she does.

I went to you tube to see what a cam phaser was. I think it was in a Ford pick up, but you will get the idea

wakebord99

This exactly describes what is going on with my car. Can you please let us know what oil additive you have used?