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Whistle..UGHH!

C

cbarto

NAXJA Forum User
Location
FT Myers FL
Ok I picked up this high pitched whistle. It drives me crazy. I only appears at 1000-2000 rpm usually at 45 to 30 mph. When you dump the throttle it starts whistling loudly, it holds pretty much the same pitch all the way to 1000 rpm and then quits before idle. It isnt affected by the steering so I don't think its the ps pump. I thinkin intake or exhaust crack / leak, but it wont do it at idle and i cant convince anyone to ride on the front with the hood off at 35mph to listen for it.(jk). Anyone?? I am gonna start tearin things off in the next day or so.

2000 4.o aw4 np231 3.5" 31x10.5
 
I had a strange whistle I couldn't track down on my YJ 4.2, turned out to be a valve cover gasket.
 
check that the air hose at the throttle body has not torn as well-- if you're pulling air past the hose where it mounts to the TB, you'll get a horrible whistle that can disappear with less airflow (idle)
 
Nothin like those sounds. Sounds like bad bearing but only has one pitch stays high no matter what you do.(steering, ac on/off, braking..) I need to make it happen while in park but havent been able to yet.
 
are you able to put it on a lift and spin the tires?

how about removing the front D/S and driving it?

Just a couple of ideas...
 
Check your intake manifold as well. Closing the throttle at speed results in very high vacuum. Once the rpms drop the vacuum eases off. My '88 does the same thing except also goes away completely when warm. Also won't do it in neutral. I changed my exh manifold and this began to happen about 2 weeks later. I just haven't had time to tighten every thing up but I'm convinced that my problem.
 
Its amazing what a cold day will produce. 40 this morning in s florida fired it up and there it was that horrible whistle. Popped the hood climbed all over it and found it at the rear of the intake. pull up on it, it quits push down it gets worse. YESSS!! Its definetly a gasket or something loose, and it goes away as the eng temp rises at idle and the intake warms up. Drive down the road a mile or so and it cools down again with the air flow and starts whistling again. So can anyone tell me the torque on the intake and if there is a pattern?
 
My 2001 whistles quite loudly too. It does get stronger with deceleration and disappears with acceleration. It starts after warmup and gets worse when it heats up rather than better like above. It sometimes goes away later, sometimes not. It unfortunately always seems to go away when I am stopped and can look for a cause!

Very much an "air" sound so I think vacuum or exhaust somewhere.

Doesn't seem to affect any vacuum controls like heater doors though.
 
MJCfromCT said:
Does it sound like this:

http://youtube.com/watch?v=e1eNi2k-94E

or this?

http://youtube.com/watch?v=N0w8x4Zcae4
Click to expand...



I dealt with those exact noises in my XJ - sounded like a friggin' train whistle! Folks at Colorado Fest 2 years ago will remember my rig and the whistling it made in the mornings........

Turned out to be an idler pully bearing going bad. Replaced the idler pulley and no more noise. I was surprised how bad the bearing was and still rotating seemingly ok......
 
I cant tell you how many times it started and got going real good so I would pull over pop the hood and nothin. Late last night as the temp started to drop I was able to pop the hood while moving, un belt and do a Chinese fire drill with the hood and try to track it. Wasn't till early this morning when it was cold I fired it up and with in a minute it was screaming sitting still. Stuck my head all over and found it at the back of the valve cover and then started pressing and pulling on the intake and TB till I made it start and stop. Guess this weekend I will re torque the intake and see if that helps.
 
If the stud bolt at back of head broke, the intake/exhaust will start to slide down and expose enough of the runners on the head to leat out an exhaust leak or in an intake leak. That bolt can be hell to remove too. Just went thru that.
 
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