Whistling Noise Under the Hood - Rubicon Owners Forum
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  • 2 Post By Al_S
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post #1 of 5 (permalink) Old 09-02-2019, 03:25 PM Thread Starter
Rubi Noobie
 
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Join Date: Nov 2013
Location: Montana
Posts: 58
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Whistling Noise Under the Hood

I've had a whistling noise under the hood for almost two years.


It only happens under the following conditions:
  • When it's cold outside
  • When the engine temp is warmish but not yet the normal 210 running temp
  • When I shift or take it out of gear
  • But not when it's out of gear and I'm standing still
The whistle is an obvious air flow issue but I cannot detect it in the shop. (I haven't yet been able to get my ears under the hood while someone else is driving.)

Of course I have checked the K&N connections and they are all tight. The whistling started long after the K&N was installed.

Has anyone experienced something like this? Any clues you can give me are welcome.
Thanks.

2004 Rubi TJ Low COG Recipe: 33x12.5 tires under flat fender flares, 1/1.25 inch motor/body lift, 2.5 inch OME suspension lift, all new JKS upper/lower control arms, more...
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post #2 of 5 (permalink) Old 09-02-2019, 10:02 PM
Rubi Wheeler
 
Join Date: Dec 2007
Location: North Olmsted, OH
Posts: 173
I had a whistling noise develop after my exhaust manifold was replaced. Turned out that the top front bolt loosened up, caused a leak at intake manifold, most noticeable right before reaching operating temp.


Seems like your situation may be due to a slight vacuum leak, temperature related. You may need to do a smoke test to check for any vacuum leaks.
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post #3 of 5 (permalink) Old 09-02-2019, 10:12 PM
Rubicus Maximus
 
Join Date: Mar 2017
Location: B.C. Canada
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When was the last time you cleaned out your throttle body and IAC motor?

2014 JKU, JKS lift,Poison spyder flares, bombshell covers,Rancho D2 control arms, JKS adjustable track bars, 35" Tires. GrabBars, Crawler Conceptz rear bumper, Smitty front bumper, Winch. Rough Country inner fenders, Teraflex Disco Mud Flaps
Backseat Dobermann Security
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post #4 of 5 (permalink) Old 09-08-2019, 10:09 AM Thread Starter
Rubi Noobie
 
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Location: Montana
Posts: 58
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Whistling Noise Under the Hood - FIXED!

Fixed! My two year teapot whistle is gone.

I checked for vacuum leaks with cleaner but found nothing.

The throttle body definitely needed cleaning so I took it out and gave it and the IAC a thorough degrease. It did NOT fix the whistle, but I noticed the whistle was different. Instead of whistling when it was out of gear between shifts, it mostly whistled while in gear just before the upshift for gears 1, 2 and 3. Weird.

When I took the throttle body off the bolts were firm but too easy to loosen. I merely made it a little more firm on the re-install. After cogitating on the whistle change, I figured I'd tighten these bolts some more. The whistling only occurs in cooler weather when the engine is warming up, so I waited until morning when it was 50 degrees and went for a drive... The teapot whistle is now completely gone.

A guy on a YouTube video said he just tightened the throttle body without worrying about the torque spec as it didn't matter. Apparently not. I didn't bother looking up the torque, for my test drive I just tightened it very firm but didn't go crazy.

The throttle body gasket was very thin but in very good shape. Next time I clean the throttle body I'm going to either put in a thicker gasket or maybe two thin gaskets. Then I'm going to torque it to spec.

Torque Matters!

2004 Rubi TJ Low COG Recipe: 33x12.5 tires under flat fender flares, 1/1.25 inch motor/body lift, 2.5 inch OME suspension lift, all new JKS upper/lower control arms, more...
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post #5 of 5 (permalink) Old 09-09-2019, 09:18 AM
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John - WB5THT
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2006 LJ, not stock
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