IanT

Recently picked up a 01 IS300 with 169k miles, unmodified. Love the car, even with the high mileage the motor is strong and chassis is tight. Impressed to say the least. However it recently started making an intermittent high pitched whining sound under the hood, kind of like a turbo whine, or whistle sound that increases upon acceleration.

I bought a mechanic's stethoscope and was able to narrow this sound down to the (edit: intake) manifold/header pipe that is second from the firewall.

The sound seems to be worse when the car is cold, then comes and goes with varying levels of intensity. Sometimes it's almost imperceptible.

It seems more related to the intake vacuum or exhaust pressure because it gets much louder when you are accelerating, even when the RPMs are basically the same.

I could post a video if that would help.

Also, the Traction Control light began flashing a couple of days ago and hasn't stopped since. I have yet to stop by Autozone for the read out, but will do that this weekend.

It has also stalled a couple of times when starting the car in the morning, but then ran fine afterwards. This had me thinking it was possibly something in the belt line that was intermittently seizing, or perhaps the belt tensioner. However with the stethoscope it is pretty clear this is coming from the (edit: intake) manifold on the cylinder 2nd from the firewall.

Even when the car is whining, the motor feels as strong as ever. Aside from the stalls when the car is cold, it runs like a champ, as if it had half as many miles.

Thanks in advance for your help!

IanT

Nobody has any ideas?

mitsuguy

iTrader: (2)

Exhaust leak is the only problem the exhaust manifold can make, but your noise sounds more like a vacuum leak, which is obviously on the intake side of things... I would go over all rubber vacuum lines and gaskets, sometimes spraying carb cleaner in an area with a vacuum leak will speed the engine up, though not always... Your trac light is flashing - is the check engine light also on??? Report back with the codes that are stored, generally the trac light will flash when there is an emissions related failure...

IanT

Thank you! I just noticed the reply so I haven't gotten to try the carb cleaner yet on the hoses. I will do that and take it to AutoZone for the code readout tomorrow. But the sound is getting worse, and almost has some grinding. The car has been stalling at idle more frequently, too, when it's cold. Once it gets going it runs fine.

Also, only the Trac light is blinking, the check engine light is not on.

I made some Vine videos yesterday, but I can't get them to embed here, it's just showing the HTML.

Here is a link.

https://vine.co/v/hP7EQzUbpY3

IanT

Ok, I fixed it. I pulled off the plastic engine cover and sprayed carb cleaner over the vacuum tubes and the intake manifold.

I was able to locate the leak coming from the intake manifold. I'm a bonehead and had mistook the intake runners as header pipes before taking off the plastic engine cover. So the sound that I had indentified with the stethoscope was coming from the intake runner not the header pipe.

The nuts and bolts were super loose. One of the nuts had rattled off completely.

I replaced it, re-torqued it, and reset the computer. The sound is gone.

Now I'll just need to see if the TRAC OFF light comes back on any time soon, and if the car continues the cold weather stalling.



Thanks again Mitsuguy for your tips!