01 XJ 4.0L Whistle
 

I have an `01 XJ 4.0L that whistles LOUD in the vicinity of the brake
booster. It only whistles when the weather is cold (about 32 F and below)
and begins after driving for about 5 minutes. The whistle goes away as the
throttle is opened, and gets louder as the throttle is closed. It does not
whistle at idle, so I'm not able to get under the hood while its happening.
My first hunch was that the brake booster vacuum line is cracked, but I
didn't see anything unusual. Have any of you had this problem and found out
what it was?

Thanks,
Ed

Re: 01 XJ 4.0L Whistle
 

Hi Ed,
Have you tried grabbing the throttle crank from under the hood? And
a piece of garden hose to use like a stethoscope.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

"Ed Bacon, Jr." wrote:
>
> I have an `01 XJ 4.0L that whistles LOUD in the vicinity of the brake
> booster. It only whistles when the weather is cold (about 32 F and below)
> and begins after driving for about 5 minutes. The whistle goes away as the
> throttle is opened, and gets louder as the throttle is closed. It does not
> whistle at idle, so I'm not able to get under the hood while its happening.
> My first hunch was that the brake booster vacuum line is cracked, but I
> didn't see anything unusual. Have any of you had this problem and found out
> what it was?
>
> Thanks,
> Ed

Re: 01 XJ 4.0L Whistle
 

Hi Ed,
Have you tried grabbing the throttle crank from under the hood? And
a piece of garden hose to use like a stethoscope.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

"Ed Bacon, Jr." wrote:
>
> I have an `01 XJ 4.0L that whistles LOUD in the vicinity of the brake
> booster. It only whistles when the weather is cold (about 32 F and below)
> and begins after driving for about 5 minutes. The whistle goes away as the
> throttle is opened, and gets louder as the throttle is closed. It does not
> whistle at idle, so I'm not able to get under the hood while its happening.
> My first hunch was that the brake booster vacuum line is cracked, but I
> didn't see anything unusual. Have any of you had this problem and found out
> what it was?
>
> Thanks,
> Ed

Re: 01 XJ 4.0L Whistle
 

Hi Ed,
Have you tried grabbing the throttle crank from under the hood? And
a piece of garden hose to use like a stethoscope.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

"Ed Bacon, Jr." wrote:
>
> I have an `01 XJ 4.0L that whistles LOUD in the vicinity of the brake
> booster. It only whistles when the weather is cold (about 32 F and below)
> and begins after driving for about 5 minutes. The whistle goes away as the
> throttle is opened, and gets louder as the throttle is closed. It does not
> whistle at idle, so I'm not able to get under the hood while its happening.
> My first hunch was that the brake booster vacuum line is cracked, but I
> didn't see anything unusual. Have any of you had this problem and found out
> what it was?
>
> Thanks,
> Ed

Re: 01 XJ 4.0L Whistle
 

Ed Bacon, Jr. did pass the time by typing:
> I have an `01 XJ 4.0L that whistles LOUD in the vicinity of the brake
> booster. It only whistles when the weather is cold (about 32 F and below)
> and begins after driving for about 5 minutes. The whistle goes away as the
> throttle is opened, and gets louder as the throttle is closed. It does not
> whistle at idle, so I'm not able to get under the hood while its happening.
> My first hunch was that the brake booster vacuum line is cracked, but I
> didn't see anything unusual. Have any of you had this problem and found out
> what it was?

With the 4.0 that's going to be 99% throttle body whistle and not the
brake booster. However, check the hose between the bosster and the
intake rail to see if it's cracked. Might be flexing under acceleration.
Clean your TB. http://members.cox.net/wilsond/tb/tb.html

With the TB closed your at max vac for idle.

That could also be a crack in the intake plastic or even a shrinking
gasket under the TB. With the engine running spray some TB cleaner
around the TB's base and puff some by the booster and it's hose.
if the engine stammers you found a leak.


--
-- DougW -- 93 ZJ 4.0 http://members.cox.net/wilsond
HESCO Supercharger - 300W IASCA Stereo - Edelbrock IAS Shocks
Gibson Exhaust - rear DCpower - custom gauge install - Stillen Rotors
Banks Header - and BEER, in the fridge!

Re: 01 XJ 4.0L Whistle
 

Ed Bacon, Jr. did pass the time by typing:
> I have an `01 XJ 4.0L that whistles LOUD in the vicinity of the brake
> booster. It only whistles when the weather is cold (about 32 F and below)
> and begins after driving for about 5 minutes. The whistle goes away as the
> throttle is opened, and gets louder as the throttle is closed. It does not
> whistle at idle, so I'm not able to get under the hood while its happening.
> My first hunch was that the brake booster vacuum line is cracked, but I
> didn't see anything unusual. Have any of you had this problem and found out
> what it was?

With the 4.0 that's going to be 99% throttle body whistle and not the
brake booster. However, check the hose between the bosster and the
intake rail to see if it's cracked. Might be flexing under acceleration.
Clean your TB. http://members.cox.net/wilsond/tb/tb.html

With the TB closed your at max vac for idle.

That could also be a crack in the intake plastic or even a shrinking
gasket under the TB. With the engine running spray some TB cleaner
around the TB's base and puff some by the booster and it's hose.
if the engine stammers you found a leak.


--
-- DougW -- 93 ZJ 4.0 http://members.cox.net/wilsond
HESCO Supercharger - 300W IASCA Stereo - Edelbrock IAS Shocks
Gibson Exhaust - rear DCpower - custom gauge install - Stillen Rotors
Banks Header - and BEER, in the fridge!

Re: 01 XJ 4.0L Whistle
 

Ed Bacon, Jr. did pass the time by typing:
> I have an `01 XJ 4.0L that whistles LOUD in the vicinity of the brake
> booster. It only whistles when the weather is cold (about 32 F and below)
> and begins after driving for about 5 minutes. The whistle goes away as the
> throttle is opened, and gets louder as the throttle is closed. It does not
> whistle at idle, so I'm not able to get under the hood while its happening.
> My first hunch was that the brake booster vacuum line is cracked, but I
> didn't see anything unusual. Have any of you had this problem and found out
> what it was?

With the 4.0 that's going to be 99% throttle body whistle and not the
brake booster. However, check the hose between the bosster and the
intake rail to see if it's cracked. Might be flexing under acceleration.
Clean your TB. http://members.cox.net/wilsond/tb/tb.html

With the TB closed your at max vac for idle.

That could also be a crack in the intake plastic or even a shrinking
gasket under the TB. With the engine running spray some TB cleaner
around the TB's base and puff some by the booster and it's hose.
if the engine stammers you found a leak.


--
-- DougW -- 93 ZJ 4.0 http://members.cox.net/wilsond
HESCO Supercharger - 300W IASCA Stereo - Edelbrock IAS Shocks
Gibson Exhaust - rear DCpower - custom gauge install - Stillen Rotors
Banks Header - and BEER, in the fridge!

Re: 01 XJ 4.0L Whistle
 

On my 93 GC with the 4.0L engine I also had a loud whistle from that
area and it was the short rubber hose (4") between the plastic pipe
coming from the PCV valve and the intake manifold. The hose on mine was
pretty soft and it would collapse under vacuum and when cold. The
whistle would go away if I moved the hose even slightly. I don't know
why it only happened in cold weather, I would expect the hose to be
stiffer due to the cold weather. I replaced it with a new hose and
haven't had the whistle since. If I recall I had to find the right type
hose since fuel line type of hose was too stiff. It took a few trips to
parts stores find the correct vacuum type hose.

Walt B


Ed Bacon, Jr. wrote:
> I have an `01 XJ 4.0L that whistles LOUD in the vicinity of the brake
> booster. It only whistles when the weather is cold (about 32 F and below)
> and begins after driving for about 5 minutes. The whistle goes away as the
> throttle is opened, and gets louder as the throttle is closed. It does not
> whistle at idle, so I'm not able to get under the hood while its happening.
> My first hunch was that the brake booster vacuum line is cracked, but I
> didn't see anything unusual. Have any of you had this problem and found out
> what it was?
>
> Thanks,
> Ed
>
>

Re: 01 XJ 4.0L Whistle
 

On my 93 GC with the 4.0L engine I also had a loud whistle from that
area and it was the short rubber hose (4") between the plastic pipe
coming from the PCV valve and the intake manifold. The hose on mine was
pretty soft and it would collapse under vacuum and when cold. The
whistle would go away if I moved the hose even slightly. I don't know
why it only happened in cold weather, I would expect the hose to be
stiffer due to the cold weather. I replaced it with a new hose and
haven't had the whistle since. If I recall I had to find the right type
hose since fuel line type of hose was too stiff. It took a few trips to
parts stores find the correct vacuum type hose.

Walt B


Ed Bacon, Jr. wrote:
> I have an `01 XJ 4.0L that whistles LOUD in the vicinity of the brake
> booster. It only whistles when the weather is cold (about 32 F and below)
> and begins after driving for about 5 minutes. The whistle goes away as the
> throttle is opened, and gets louder as the throttle is closed. It does not
> whistle at idle, so I'm not able to get under the hood while its happening.
> My first hunch was that the brake booster vacuum line is cracked, but I
> didn't see anything unusual. Have any of you had this problem and found out
> what it was?
>
> Thanks,
> Ed
>
>

Re: 01 XJ 4.0L Whistle
 

On my 93 GC with the 4.0L engine I also had a loud whistle from that
area and it was the short rubber hose (4") between the plastic pipe
coming from the PCV valve and the intake manifold. The hose on mine was
pretty soft and it would collapse under vacuum and when cold. The
whistle would go away if I moved the hose even slightly. I don't know
why it only happened in cold weather, I would expect the hose to be
stiffer due to the cold weather. I replaced it with a new hose and
haven't had the whistle since. If I recall I had to find the right type
hose since fuel line type of hose was too stiff. It took a few trips to
parts stores find the correct vacuum type hose.

Walt B


Ed Bacon, Jr. wrote:
> I have an `01 XJ 4.0L that whistles LOUD in the vicinity of the brake
> booster. It only whistles when the weather is cold (about 32 F and below)
> and begins after driving for about 5 minutes. The whistle goes away as the
> throttle is opened, and gets louder as the throttle is closed. It does not
> whistle at idle, so I'm not able to get under the hood while its happening.
> My first hunch was that the brake booster vacuum line is cracked, but I
> didn't see anything unusual. Have any of you had this problem and found out
> what it was?
>
> Thanks,
> Ed
>
>