2.5L engine whistle at idle - JeepForum.com
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post #1 of 9 Old 01-13-2008, 05:08 PM Thread Starter
Jeepdawgs
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2.5L engine whistle at idle

I have had an engine (2.5L) whistle at idle for awhile now. It will happen when I start it up and when the engine is at idle (clutch in or neutral). It does not get better or worse after the engine is warmed up. It is not present when I press the throttle. I just replaced my idler pulley on my Envoy. When that went out, the engine sounded like a diesel and the noise was present at idle and when I would accelerate. Since the whistle is only present at idle, or when the throttle is not pressed, I am taking an educated guess that it is a vaccum leak. Is my SWAG (scientific wild a** guess)correct and if so what is the best way to test for a vaccum leak?


'99 Gun Metal Blue TJ
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Mauser K98 (1941),K31(early 50's), Mosin-Nagant M44 (1946), BUL Impact .45, Ruger Mark2, CZ-50, Marlin .22, Winchester.22
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post #2 of 9 Old 01-13-2008, 05:49 PM
mall0y
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What kind of whistling? Is it more like an Intake/TB whistling or a bad alternator/bearing whining?
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post #3 of 9 Old 01-13-2008, 05:56 PM Thread Starter
Jeepdawgs
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Quote:
Originally Posted by mall0y
What kind of whistling? Is it more like an Intake/TB whistling or a bad alternator/bearing whining?

My thinking with bearings is that they would still whine at higher RPM's. Since the sound goes away at higher RPM's I was guessing that I had a vaccum leak somewhere. It sounds like air going through a small opening.

'99 Gun Metal Blue TJ
5 spd Manual
31x10.50 BFG KO's
2" Tereflex lift, Rancho Steering Stablizer
Mauser K98 (1941),K31(early 50's), Mosin-Nagant M44 (1946), BUL Impact .45, Ruger Mark2, CZ-50, Marlin .22, Winchester.22
Low Output 4-Cylinder Jeep Club #50
"Dyslexia for cure found"
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post #4 of 9 Old 01-13-2008, 06:48 PM
JeeperAbe
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I had the same problem..make sure your exhaust and intake manifolds are tight and torqued to spec...i had a leak and it was from a loose bolt.

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Mods to come: 2" Coil lift, 31 MTs, Bumpers, Lights, Skids
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post #5 of 9 Old 01-13-2008, 07:45 PM
carpekd
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have you checked the vacuum lines under the hood? I've heard stories of them dry-rotting and crumbling to pieces.
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post #6 of 9 Old 01-13-2008, 08:12 PM Thread Starter
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Quote:
Originally Posted by carpekd
have you checked the vacuum lines under the hood? I've heard stories of them dry-rotting and crumbling to pieces.

I just checked them. They visually look OK. I am debating on just replacing them anyways incase there is a pinhole in one that I can't find. Can't be too expensive, might be the cheapest thing to do first.

'99 Gun Metal Blue TJ
5 spd Manual
31x10.50 BFG KO's
2" Tereflex lift, Rancho Steering Stablizer
Mauser K98 (1941),K31(early 50's), Mosin-Nagant M44 (1946), BUL Impact .45, Ruger Mark2, CZ-50, Marlin .22, Winchester.22
Low Output 4-Cylinder Jeep Club #50
"Dyslexia for cure found"
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post #7 of 9 Old 01-14-2008, 06:57 AM
erickpl
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I'd suspect a cracked manifold. The 97-2000's were notorious for that.

-Paul
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post #8 of 9 Old 03-19-2019, 08:31 PM
twhitakerWV
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Hi,

Very similar issue for me on a 1995 Rio Grand 2.5L. Whistle at idle but goes away when given gas.

I just visited my local shop and the mechanic sprayed some penetrating oil on the manifold and the whistle stopped when this part was hit. See arrow in photo.

He said would be $500-600 to remove, clean, and fix everything. Any other DIY tips?

Thanks!
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post #9 of 9 Old 03-19-2019, 11:31 PM
mukluk
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@twhitakerWV
Your arrow is pointing at a casting seam on the intake manifold. If you mean a point just to the left of the arrow tip, the leak is located where the intake manifold meets the cylinder head. Fixing this leak will require removing the intake manifold and replacing the manifold seal. If however you mean a point just to the right of the arrow tip, that is your #3 fuel injector. Fixing this leak is much easier and only requires pulling the fuel rail and injectors out of the intake manifold and replacing the o-ring seals on the injectors (might as well do all four since you can't remove just one).
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