'90 XJ High-pitched whistle and idles high
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Model: Cherokee
'90 XJ High-pitched whistle and idles high
Sounds like a vacuum leak under hood. Goes away as throttle is increased.
Does it intermittently after engine is at operating temp.
Whistles really loud and very high in pitch @ idle and slightly above idle , then goes away as throttle is opened more. It is driving me crazy. Embarrassing , but the Jeep drives/runs fine otherwise.
Got it to do it with hood open in driveway and sounds like it is near the top of the engine but cannot pin point location. Checked all vacuum lines I can see.
Anyone had this problem ?
t definitely sounds like a vacuum problem to me , not a bearing noise , the other giveaway being the idle jumping from usual 650 or so up to 1000 RPM and staying there (lean condition).
Idle speed is normal when sound goes away.
Help !!!
Does it intermittently after engine is at operating temp.
Whistles really loud and very high in pitch @ idle and slightly above idle , then goes away as throttle is opened more. It is driving me crazy. Embarrassing , but the Jeep drives/runs fine otherwise.
Got it to do it with hood open in driveway and sounds like it is near the top of the engine but cannot pin point location. Checked all vacuum lines I can see.
Anyone had this problem ?
t definitely sounds like a vacuum problem to me , not a bearing noise , the other giveaway being the idle jumping from usual 650 or so up to 1000 RPM and staying there (lean condition).
Idle speed is normal when sound goes away.
Help !!!
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Model: Cherokee
Wow...I was hoping it wasn't that but that is where it is.
If I find the location I will use high-temp silicone on it. Gotta be a small hole.
If I find the location I will use high-temp silicone on it. Gotta be a small hole.
Last edited by bufbarnaby; Sep 10, 2015 at 10:59 PM.
CF Veteran
Joined: Jan 2015
Posts: 1,381
Likes: 3
From: Southern Maryland
Year: 1991
Model: Cherokee
Engine: 1999 4.0L
3-foot section of 1/2" hose in your ear is good for localizing sharp noises.
If you hear it around the throttle body, replace the throttle body gasket with new dealer piece; the old ones get brittle and crack. Also remove the IAC and remove the IAC sub-housing from the throttle body. Clean it all up and replace that gasket with RTV.
If you hear it around the throttle body, replace the throttle body gasket with new dealer piece; the old ones get brittle and crack. Also remove the IAC and remove the IAC sub-housing from the throttle body. Clean it all up and replace that gasket with RTV.
Thread Starter
Junior Member
Joined: Jan 2014
Posts: 37
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Model: Cherokee
3-foot section of 1/2" hose in your ear is good for localizing sharp noises.
If you hear it around the throttle body, replace the throttle body gasket with new dealer piece; the old ones get brittle and crack. Also remove the IAC and remove the IAC sub-housing from the throttle body. Clean it all up and replace that gasket with RTV.
If you hear it around the throttle body, replace the throttle body gasket with new dealer piece; the old ones get brittle and crack. Also remove the IAC and remove the IAC sub-housing from the throttle body. Clean it all up and replace that gasket with RTV.
Going out now to investigate.
Thread Starter
Junior Member
Joined: Jan 2014
Posts: 37
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Model: Cherokee
3-foot section of 1/2" hose in your ear is good for localizing sharp noises.
If you hear it around the throttle body, replace the throttle body gasket with new dealer piece; the old ones get brittle and crack. Also remove the IAC and remove the IAC sub-housing from the throttle body. Clean it all up and replace that gasket with RTV.
If you hear it around the throttle body, replace the throttle body gasket with new dealer piece; the old ones get brittle and crack. Also remove the IAC and remove the IAC sub-housing from the throttle body. Clean it all up and replace that gasket with RTV.
Have RTV too : )
TB gasket was cracked at the middle on the valve cover side. Though I could not get it to whistle , I got it to make a honking sound after I loosened the TB bolts.
The dreaded whistle is back...NOT the TB. Did it at AZ in parking lot to get TB gasket.
Put on stethoscope with bell removed and listened with tubing end.
Sound very loud near #1 injector....hope it is this , NOT the intake gasket. Fuel rail looks easy to take off.
Do the O-rings ever get brittle and leak...port FI there has to be vacuum at this point , no ?
Last edited by bufbarnaby; Sep 13, 2015 at 03:27 PM. Reason: more info.
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Model: Cherokee
Great idea...happen to have a LOT of 1/2 inch hose as I bought the wrong size a while back.
Have RTV too : )
TB gasket was cracked at the middle on the valve cover side. Though I could not get it to whistle , I got it to make a honking sound after I loosened the TB bolts.
No ride so I carefully put on a bead of RTV HI-TEMP and closed it up.
No noise so far and will do a better job with a gasket later.
Was wondering...rubber grommet where MAP sensor plastic vacuum line connects at base of TB is almost in same place.
Can that grommet be replaced ? Do they leak ?
Have RTV too : )
TB gasket was cracked at the middle on the valve cover side. Though I could not get it to whistle , I got it to make a honking sound after I loosened the TB bolts.
No ride so I carefully put on a bead of RTV HI-TEMP and closed it up.
No noise so far and will do a better job with a gasket later.
Was wondering...rubber grommet where MAP sensor plastic vacuum line connects at base of TB is almost in same place.
Can that grommet be replaced ? Do they leak ?
Last edited by bufbarnaby; Sep 13, 2015 at 03:29 PM.
Thread Starter
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Joined: Jan 2014
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Model: Cherokee
OMFG !!!
3-foot section of 1/2" hose in your ear is good for localizing sharp noises.
If you hear it around the throttle body, replace the throttle body gasket with new dealer piece; the old ones get brittle and crack. Also remove the IAC and remove the IAC sub-housing from the throttle body. Clean it all up and replace that gasket with RTV.
If you hear it around the throttle body, replace the throttle body gasket with new dealer piece; the old ones get brittle and crack. Also remove the IAC and remove the IAC sub-housing from the throttle body. Clean it all up and replace that gasket with RTV.
Also , my Jeep has always run kinda hot and I suspect it has been running too lean with the leak.
On the way home from the gym it was like 25F cooler than usual !
Could that have fixed my hot-running engine issue also ???
NO MORE WHISTLE !
CF Veteran
Joined: Jan 2015
Posts: 1,381
Likes: 3
From: Southern Maryland
Year: 1991
Model: Cherokee
Engine: 1999 4.0L
It was the two front manifold bolts. So loose could turn with fingers.
Also , my Jeep has always run kinda hot and I suspect it has been running too lean with the leak.
On the way home from the gym it was like 25F cooler than usual !
Could that have fixed my hot-running engine issue also ???
NO MORE WHISTLE !
Also , my Jeep has always run kinda hot and I suspect it has been running too lean with the leak.
On the way home from the gym it was like 25F cooler than usual !
Could that have fixed my hot-running engine issue also ???
NO MORE WHISTLE !
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
It was the two front manifold bolts. So loose could turn with fingers.
Also , my Jeep has always run kinda hot and I suspect it has been running too lean with the leak.
On the way home from the gym it was like 25F cooler than usual !
Could that have fixed my hot-running engine issue also ???
NO MORE WHISTLE !
Also , my Jeep has always run kinda hot and I suspect it has been running too lean with the leak.
On the way home from the gym it was like 25F cooler than usual !
Could that have fixed my hot-running engine issue also ???
NO MORE WHISTLE !
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