Squealing noise on my 2002 4.0

YooperSkipper

YooperSkipper

Member
Joined
Jan 31, 2018
Messages
55
Location
Michigan, United States
There is a squealing noise coming from my engine which comes and goes. It usually starts shortly after starting when the engine warms a little. I replaced the belt and checked all the pulleys. I'm thinking it sounds like a vacuum leak but have not been able to locate any. Anyone have any thoughts?
 
To me when someone says squeal, I think of belt. Everyone describes noises differently. Hard to diagnose words in a sentence. Changing the idler and tensioner pulley for peace of mind is cheap and easy and it is a good PM action, but that may not be your issue. If you think it is vacuum, look at all hoses one by one. There aren't too many of them.
 
Double check your belt routing, it’s pretty easy to mid-route it and still have it look correct. This is what it looks like if you have AC but you might double check yours specifically.

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A hiss is a vacuum leak general, and a squeal is a belt / pulley.

I would bet it's one of the pulley bearings. Could be the idle, alternator, or a variety of other pulleys.

I always figure out it which one it is by spaying WD-40 at the pulley individually while it's squealing. When the WD-40 makes the squeal go away, I know which one is my culprit.
 
Grab a mechanic's stethoscope and start narrowing it down. Don't overlook the camshaft synchronizer (also known as the OPDA on 05 and 06 models). Mine began squealing and it sounded exactly like a belt.
 
need a diagram serpentine belt diagram for an inline 6 cyl starts wit the alternator on the left the an idler below is a tensioner crank on the bottom belt above and power steering on the right no AC 2003 wrangler 4l straight 6
 
My ‘06 had a high pitch squeal when I first started it up cold. It went away before I could get out and open the hood, but it sure sounded like a belt or an idler going bad. I told my wife we’d have to live with it until it got bad enough to diagnose. Well, it did and it didn’t take long to realize it changed when the clutch was engaged. Yep, my bad idler was actually the throwout bearing going bad. It sure fooled me.

JohnnySombero
 
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