4.0 TJ making loud engine whistle - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ General Discussion Forum

Join Wrangler Forum Today

Like Tree3Likes
  • 1 Post By mlowery1298
  • 2 Post By Greyound04
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 10-10-2019, 02:50 PM
Thread Starter
Join Date: Oct 2019
Location: Upstate NY
Posts: 2
Question 4.0 TJ making loud engine whistle

My 03 TJ has had a loud engine whistle for some time now but it only occurs when cold outside most of the time. It wont start until the engine is running for about 5 to 10 mins. It will squeal until i press down on the gas and start again when i let my foot off. It gets progressively louder until eventually it will stop. Ive checked all pulleys and the belt tension, even replaced throttle body gaskets and cleaned the throttle body. Only thing i can think of is a possible air leak somewhere. If anyone else has had this problem it would be a big help to try to fix this. Doesnt effect how the engine performs it is just annoying and can be very loud.

Nynico likes this.
mlowery1298 is offline   Quote
Old 10-10-2019, 04:27 PM   #2
Join Date: Apr 2012
Posts: 1
Tighten manifold mounting bolts to spec.

Sent from my iPad using Tapatalk
tzukows and Nynico like this.

Greyound04 is offline   Quote
Old 10-16-2019, 10:58 AM   #3
tzukows's Avatar
Join Date: Feb 2018
Posts: 877
You may have a big vacuum leak somewhere. Greyhound made a great suggestion with the manifold gasket. It may be sealing itself up when the engine warms.

I had problems with the vent tube that connects between the intake manifold and the rear elbow on the valve cover. There is a short piece of rubber hose making the connection between the end of the tube and the intake manifold. Mine had a big split in the rubber hose.

I tried 1/2 inch heater hose, but it kept splitting. A big vacuum leak would start whistling louder and louder. The engine would not idle down when foot was off the gas pedal, because the computer was thinking it was not getting enough gas (because there was waaay too much air coming into the manifold through the split hose).

I must hav gotten a more flexible bit of hose, because the problem has not returned.
/l ,[____],
l---L -OlllllllO-
05 TJ Rubicon
tzukows is offline   Quote
Sponsored Links
Old 10-16-2019, 11:01 AM   #4
TheBoogieman's Avatar
Join Date: Jul 2016
Location: CharlottesHELL, Va
Posts: 2,494
Attached Thumbnails
Click image for larger version

Name:	Vacuum Leak Potential Sites.JPG
Views:	18
Size:	93.3 KB
ID:	4180357  
03' Rubicon/Zone 4.25" combo lift/Rancho 9000XL shocks/5.13 gears-35" MTZs/LoD bumpers/Black Magic brakes
99' XJ under construction/ 5.5" lift/ Rancho rs5000x shocks/HP30-8.25/ 33" DC MTs. (JEEP #18).
TheBoogieman is offline   Quote
Old 10-17-2019, 08:11 AM   #5
n0useforaname's Avatar
Join Date: May 2016
Posts: 61
Mine did the SAME thing. Ended up being my manifold bolts were loose. I thought it was a vacuum leak, PS pump, belt, pulleys, etc.. I dropped quite a bit of cash for nothing.
99 Wrangler Sport 4.0 Auto - 4.10 gearing
3.5" lift - 33X12.50/18
Currie currectlync and front track bar
Redhead steering box - Cervinis cowl hood
doubleDIN center mod w rear seat 10" sub mod
bed tred carpet w raptorlined dash/plastic
n0useforaname is offline   Quote
Old 11-18-2019, 02:37 PM
Thread Starter
Join Date: Oct 2019
Location: Upstate NY
Posts: 2
I recently tightened all the manifold bolts and even the bolts on the 2 down pipes from the manifold which were a bit loose. Stopped the problem for about 45mins of driving then it resumed the same as before. Might check the hose discussed above but other than that im not sure what it could be
mlowery1298 is offline   Quote
Old 11-18-2019, 03:31 PM   #7
Supporting Member

5-Year WF Supporting Member
Gold Miner's Avatar
Join Date: Jan 2013
Location: way up thar
Posts: 766
My money is on idler pulley. Before you start it on the next cold morning... squirt the backside of the idler with Tri-Flow. If it's the idler your problem will be solved for a couple of days then start whistling again. Pulley is only about $20 if that's what it turns out to be.

'01 Sahara, Original Owner
Miner with a heart of Gold.

EARTH FIRST! .......... we can mine the other planets later.
Gold Miner is offline   Quote

engine 4.0 , help 2003 tj , jeep tj , loud noises

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

All times are GMT -5. The time now is 09:29 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.1
User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, Gladiator, Mopar and Grand Cherokee are copyrighted and trademarked to FCA US LLC.
Wranglerforum.com is not in any way associated with FCA US LLC.