comotiger

Hi folks,

I purchased a 2014 LWB six weeks ago. The vehicle runs great. For the last three weeks, I hear an unusual high-pitched sound when starting the engine for the first time that day (temperature between 40-60F). See videos below. Ride height is set to normal, so I don't think it is the air compressor. You may notice that the whine goes away when the idle rpm falls from 1500 on the first start. Should I be worried? Thanks for all your help.

Best wishes,
AC


First start (8PM), driver window open, high-pitched motor whine

Second start (8:05), window open, normal engine noise

Third start (8:10), window closed, normal noise

retlex

Your sound was similar to mine, but your sound is louder. Lexus had the car overnight so they could duplicate the cold start. It turned out to be the manifold heat shield located on the passenger side. I would drop the car off at the Lexus dealership so they are able to duplicate the sound (most likely when the engine is cold). Hope you can get it resolved.

comotiger

Thanks. Was yours fixed under warranty or an expensive fix?

retlex

It was covered under warranty. I bought the car as a CPO, but at the time it was still under the 4 yr/50. For what its worth, all they did was remove the passenger side air filter box and adjusted the heat shield underneath the manifold. Whether it is the heat shield or not, I would most definitely take it to the Lexus dealership and let them handle it.

comotiger

Hi folks,
I am re-starting the thread to see if there are any more suggestions for the engine noise. It happens only on the first engine start of the day. The second start a few minutes later with the engine still cold is fine. There is a good suggestion that it may be the heat shield, which I will get checked out in a few days at my Lexus dealership. It would be nice to have more things to check out. Thanks for all your help.
Best wishes,
AC

caha14

After a cold start, once engine speed drops from 1,500 rpm and things quiet down, have you given it gas to get it back up to 1,500 rpm and see if the noise come back? You are hitting a resonant frequency at 1,500 rpm that's making whatever shield, box or other loose/poorly-supported item buzz.

Separately, I would try the same thing with the car parked after the engine is warm to see if the same noise happens. In either case, it sounds like it should be easy to replicate.

comotiger

Thanks for your input. I haven't revved it back up to 1500 in Park to see if the noise returns. Will try it but suspect the noise won't return. I usually back up out of the garage and the noise doesn't return (I am guessing I exceed 1500 while backing). I agree it's something resonating at 1500. On the 2nd and 3rd start videos, the rpm did not exceed 1400 upon starting and the noise was absent.

I don't think the noise occurs when starting a warm engine. Then again, when I start the 1st time the car is in the garage and the noise is amplified. Upon warm starts, the car is usually outside the garage, so the noise may be less evident. In any case, I am planning to leave the vehicle at the dealership overnight to replicate the noise. I hope it is an easy and not too expensive fix. The car still has the new car warranty, so hopefully the repair will be covered.

caha14

I'm eager to hear what you find out, especially in a cold start. I have watched your first video multiple times and am almost positive that if you push it right back up to 1500, you will again hear the noise. I doubt you cross the 1500 rpm mark when backing up, but even if you do, once the car is in gear, you have other loads on the system which may attenuate the vibration.

If it also happens after a warm start, that would be "gravy". If, on the other hand, it doesn't, then we have another variable: temperature.

comotiger

Ok, so I tried these conditions as suggested. The movies are attached. The driver window is open. Sadly (or should I say happily!), the noise did not occur on today's first start (cold) or hot start (after driving 2 miles). On the cold start, the engine barely went up to 1500 before settling on 1400, so maybe there wasn't enough time for the resonant vibration to develop. When revving up to 1500, there was no vibration either, so I don't know what to make of it.

Cold start

Hot start

comotiger

Update: Took it to my Lexus dealer over the weekend. They diagnosed it as a loose heat shield at the catalytic converter. It is being repaired under warranty. Hopefully the fix works!

droclex

Good to know and I hope that it completely eliminates that noise. I've been listening closely to my 13's engine and it purrs like a big V8 is supposed to; yours should too!

comotiger

You don't hear the clackety-clack of the direct injection at idle?

droclex

Music to my ears!

comotiger

Final update: Turns out it was not a loose heat shield. The order says "Left side exhaust manifold heat shield cracked and rattling. Remove and replace left side manifold". It was replaced under warranty, and the noise is gone .

roadfrog

Thanks for the update! Too often, people get a resolution to their issue and then don't post an update....