snimren

Sounds like the same issue I have reported here:
https://www.clublexus.com/forums/rx-...rt-rattle.html

arrowroot

your link doesn’t appear to be working for some reason.

ghost31711

well, did that fix the problem ?
i have the same noise too, and i always thought that is just how it but then i got the new 2019 ES350 as a loaner and OMG that engine is so quiet, so i definitely think something is wrong, but hopefully it's something that ca be fixed

GSFRX350

The rapid knocking noise on cold starts is a badly designed port where the vacuum pump attaches to the cylinder head sub-assembly. The initial TSB had dealers replace the vacuum pump only, this didn't help the problem as it's to do with the port that, in noisy engines, is perfectly round. Apparently when the engine is cold the oil "slaps" around that area making the knocking type noise you hear. When the engine warms as does the oil the oil is more liquid and the noise stops.

For those who want to have it repaired there was ANOTHER TSB (number unknown) that replaces the vacuum pump and the cylinder head sub-assembly. The sub-assembly has a port where the vacuum pump connects, noisy engines have a perfectly round hole but the updated one has a notch cut out which apparently is enough for the oil to stop "slapping" around in that area. To have the work done it's a BIG job, the entire engine is dropped from the car, broken down to remove the cylinder head sub-assembly and replace that as well as the vacuum pump. once complete the noise is pretty much gone, although I have noticed it occasionally when it's in the garage, with the car window open. Probably more to do with me listening for it but totally acceptable now and goes when the engine warms within a minute or two.

nbailz

@GSFRX350 Thanks for the insight. I'll try to find that TSB. From your post it sounds like you had this job done....was it under warranty? Was this like a $2-3k job? Doubt i could get my dealer to do this considering they initially said the noise is "normal".

GSFRX350

I'm in Australia, yes under warranty, in fact the dealer talked me into doing it. They had diagnosed the problem months before but when they told what happens to repair the problem I was hesitant because it's major surgery on the vehicle and I basically don't trust mechanics much - had too many things go wrong in the past with dealer servicing (not Lexus). After speaking at length to the service adviser and mechanic who would do the job I was put at ease and seems he did a perfect job.

They called me in to look at something else on the car and I saw my engine, on the floor, in what looked like 100s of pieces, hard to imagine what's required to replace two parts.

It's around AUD 5,000 so in the US 3,000. I think dealers are hesitant to do big jobs under warranty, especially when it's purely a short lived noise, as they don't get the same compensation from Lexus as they would if it was the customer paying. My dealer is keener to do work because it's better than nothing, a very small rural dealer who only sells around 80 cars a year.

ghost31711

dealers probably need more jobs like this now that they are not selling as many cars because of COVID 19

arrowroot

Other than the ticking/knocking noise being a nuisance, is the noise indicatve of a mechanical problem?

If it's purely a nuisance and doesn't have any effect on performance/longevity of the vehicle, I may forego this TSB - I'm not keen on having the mechanic take apart my engine into 100 pieces.

GSFRX350

Yes, I know how you feel. It's quite a sight to see it on the floor. Obviously they have to remove the drive shaft to the rear, front suspension is disconnected, exhaust, the drive chains for the valves, just a multitude of things that looks like a big jig-saw puzzle.

Definitely no mechanical problem, just oil slapping around while cold. I thought I'd get it done while in warranty as it maybe harder to sell if a prospective buyer heard it.

LwagsHamp

I had an 09 that had a ticking sound for the first minutes. Sounded like low oil. Would go away after a few minutes. Never caused a problem. No similar sound in my 2020.

Taasadi

Any update on this? is it really vaccum pump and port, It looks a big and scary job!

Appreciate if owners provide their experience with issue and solution.

Thanks.

mikem0025

Mine was ticking too and I went to the dealer 3 times. On the third time I convinced them to keep the car over night. The next day I got a call and it was confirmed that I need a new vacuum pump because “it is a known issue in these Lexuses” which is disappointing on their end. Get the new part while the warranty is active. Show them this post, YouTube videos, etc

ColonelTrt

I think it was the vacuum pump which they replaced because I really haven't heard it since unless I just got used to it..lol

It was replaced under warranty

pentiumvi

Did you ever get this figured out?
My 4RX has the same sound, dealer looked it over and said it was something to do with the ABS self-check and that it's normal. That would sort of explain why it only ever occurs when you first start driving after start-up.
I'm a little skeptical about the explanation though....

cap217

There are so many threads and some get auto combined so it gets confusing.

I am dealing with a loud noise.... Cold start, put it in gear, move at 1-3 mph like you are backing out of your garage or pulling in, and you hear this crazy loud knock. I have been through the ringer with Lexus, dealerships, corporate, etc and I am told its "normal". The techs DO NOT agree but their hands are tied. They replaced my vacuum pump but its still there. They are convinced its the pump and there is a service bulletin but the fix doesnt resolve the noise, just lessens it. Mine just gets louder. Still not giving up.