SC3coupe

iTrader: (4)

My 93 SC300 started to make this whistle noise sounds similar like a wooden flute (serious, but pitch doesn't change much) between 2000-3000 RPM accel and decel. When it's cold it's quite noticeable, but when the running on the freeway for 30 minutes and warm outside temperature it goes almost silent until the next cold start. But I can still hear it fainly. A/C doesn't seem to make a difference.

Here is the self diagnostics and thoughts..
I am able to hear the sound revving and it comes from the drive belt or fan area. So it's not a vac hose or throttle body leak. Shouldn't be alternator bearing as that usually sounds through out the RPM range. Since the sound quiets when the engine gets nice and hot, I am thinking it is not a bearing but something to do with rubber.
The belt feels tensioned enough. I did a lot of reading about the 2JZ and seems like the harmonic balancer rubber starting the crap out can cause noises like this. The car has 140k miles but it is 23 years old.

It's a $275 part and I just wanted to know is there a good way to check. Do look at the belt when revving to see if the crank pulley seems to move forward and back and the belt should ride "true"? The whistle is fairly subtle when revving so I may not be able to find anything at all.

What do you think the chances are the harmonic balancer is bad.. should I also replace the idle tensioner pulley / belt at this time?

I am thinking to park the car until I get this fixed, I don't want the pulley to come off.

eknine9

iTrader: (8)

To test the harmonic balancer, take the serpentine belt off and try to move the inner circle of the harmonic balaner with your hands, there should be no play on the part of the harmonic balancer that the serpentine belt wraps around. If you can get that to jiggle at all, or if it separates entirely that means its time for a new one. It's usually more of a screech than a whistle though for a bad harmonic balancer but give it a few strong nudges/tugs and see if its trying to seperate into two pieces or not. It's a pretty quick thing to diagnose.

You can also attach a 22mm nut to the cran bolt that goes through the harmonic balancer and then attach a big breaker bar to it and attempt to turn the motor over by hand. If you notice the inner circle of the harmonic balancer start to twist before the outer circle then it also means the balancer is bad. However the first method of simply grabbing it with the belt disconnected and trying to twist it and see if there is any play is a bit easier IMO.

Ali SC3

iTrader: (10)

you sure its not the intake whistle? check your rubber intake pipe for cracks, especially underneath where that plastic resonator box is. holes or cracks on the intake would probably make that noise and cracks in old plasticb intake are more common by this age unless the car was garaged its whole life.

I have a funny squeak type noise sometimes when it idles at a really low rpm, been wondering if I should do my harmonic balancer as well after reading those threads but its hard to say what exactly is what sound without testing things. it is a good idea to do it though at some point the harmonic balance does go on these motors, just a matter of when and where. at least non vvti is non interference if you are on stock cams.

Biddles

iTrader: (2)

PCV valve can cause a whistle noise like you're describing. Worth a check, hell worth just replacing considering how cheap it is.

SC3coupe

iTrader: (4)

Here is a video of the noise, taken when the engine is cold.

I put my ear on the PCV valve, but it does not seem to be from there.
It seems to be more from the driver side valve cover though. Which there is like another air valve there. But really hard to tell because it is kind of hard to pin point by myself. (seems like it's "down there")

I have ordered a new belt and bearing for the tensioner to see first if that helps.

So the tensioner for the sc300, you turn clockwise to loosen the belt, but you turn counter clockwise on the bolt to remove the pulley, right...?

Ali SC3

iTrader: (10)

check the idle valve where its attached to the throttle body there is a passage there on the side, you can see its the raised portion. makes sure its all cleared out, you can remove the idle valve, clean it, clean the insides. if you have blockage there from carbon buildup maybe it could make that sound, I only mention cause I hear the pitch change when coming off revs and going to idle, and usually what happens engine wise is that iacv plunger is moving around so it could be part of it making the whistle like a fancy flute or something.

tension er I think you are right. it comes off normal thread. it normally says on the sticker on the hood if its a reverse thread like I think the 2uz does.

SC3coupe

iTrader: (4)

Thanks, there is no sound at all around the TB / intake hose area , I just cleaned the TB not too long ago and removed any carbon but I am not sure I remember taking the idle valve off. Idle is very steady though.. so that might not be it but good point about the sound change and I will keep that in mind

SC3coupe

iTrader: (4)

So I replaced the tensioner pulley (new pulley and bearing), new bayco belt,
whistle still occurs.
I didn't drive the car for a few weeks in fear it's the crank pulley separating, but I found a good tip somewhere, which is to use a paint marker across the inner and outer of the pulley, and I recreated the noise but marker didn't move, so the pulley should be good and the car is safe to drive. The crankpulley didn't have play and the belts and pulleys rides straight and true. Also, all the pulleys spin without any grinding.

So it could be air leak related I will continue to look for it, I will check the bolts on the intake manifold to see if they have come loose.

SC3coupe

iTrader: (4)

Just to follow up I have fixed the problem. The valve cover bolts were loose. About 2 years ago I installed OEM valve cover gasket, along with those OEM special donut washers. Torqued to spec which is not very much.

I checked the bolts there were a couple that was not as tight near the front where the sound is. I went around and snugged all the bolts and the sound is completely gone (one bolt under the manifold cannot reach, though) Apparently the gasket probably shrunk a little and causing a gap and loose bolts and crazy kettle whistle sound.

So with a new belt and tensioner pulley engine is sounding better than before I started. I also have a marker paint on the crank pulley so I can monitor any separation down the road.

Ali SC3

iTrader: (10)

Nice find, that is sure an odd one. I have never used the donut washers. I just use a 1/4 socket set and torque till they are tight and no more than that. using the smaller socket helps prevent over tightening by accident.

SC3coupe

iTrader: (4)

Yes, certainly thought about this one and lucked out a bit.. since it goes away when hot I knew it was something rubbery.
I believe the washers provides constant expansion or block oil seepage or something, I know some supra guys swear by it. I think a dap of RTV under the bolt head works as well.

I feel the right torque is using a 10mm standard length wrench pulled finger tight, won't strip
still tighter than stock (72 inch pound),
when I used the beam torque wrench to check on a couple of bolts it has loosened to maybe 30-40 inch pound. Then decided to just go with 10mm wrench since it can reach most bolts, and snugged up while engine is hot.

Willp79

I have 92 sc300 with a similar problem.It starts to whistle once it’s warmed up and the rpm is running high. It gets louder when I hit the throttle.It started doing it after I did an antifreeze flush on it.I posted a video.Any ideas?

LeX2K

Remove the drive belt and see if the sound is still there. Assuming you tried the fix in post 9.

SC3coupe

iTrader: (4)

Yours seem a little more high pitched. Possibly you dripped some antifreeze somewhere. Removing the belt is a good idea on these cars to test it.
As I mentioned I tightened the valve cover bolts because it was wheezing.