Screeching sound coming from A/C or alternator area

[tlobaugh]

Got up this morning to go out and my 97 TJ had a very loud screeching sound on startup. Extremely loud, even sitting in the car it's very loud. I can rev the engine a bit and it goes away for a few second but then resumes. Noticed it for a brief second on start up yesterday but it went away after a couple seconds so didn't give it a second thought. Also it was cold this morning around 30 degrees if that makes a difference.

Tried driving through the neighborhood hoping it would go away but it didn't. I parked and opened the hood and it sounds like it's coming from the a/c compressor or alternator area, I'm leaning more towards it coming from the a/c if I had to guess.

It won't let me insert the video in this message so I attached it as an mp3. Phone was right above the compressor when recording.

Now that it's back to running normally I turned on the a/c and the clutch turns on, no noticeable changes in sound when it's running quietly.

Any ideas for troubleshooting this?

 

[Gilaguy23]

After a start the alt is loaded up bringing the battery back up. Loose or a worn belt or contaminated can cause this. My 99 did this once the battery got weak from sitting for weeks.

 

[ColoJeep]

Got up this morning to go out and my 97 TJ had a very loud screeching sound on startup. Extremely loud, even sitting in the car it's very loud. I can rev the engine a bit and it goes away for a few second but then resumes. Noticed it for a brief second on start up yesterday but it went away after a couple seconds so didn't give it a second thought. Also it was cold this morning around 30 degrees if that makes a difference.

Tried driving through the neighborhood hoping it would go away but it didn't. I parked and opened the hood and it sounds like it's coming from the a/c compressor or alternator area, I'm leaning more towards it coming from the a/c if I had to guess.

(Of course when I got out to record a video it won't make the sound anymore).

Now that it's back to running normally I turned on the a/c and the clutch turns on, no noticeable changes in sound when it's running quietly.

Any ideas for troubleshooting this?

How is your belt tension , it could be a little loose and is adjustable on earlier model TJ . Cold start squealing is a sign when the charging system is under alot of load as Gilaguy said. It's not hard to do.

 

[tlobaugh]

After a start the alt is loaded up bringing the battery back up. Loose or a worn belt or contaminated can cause this. My 99 did this once the battery got weak from sitting for weeks.

Belt looks fine and I've been driving the jeep regularly so don't think the battery is low. Will take a look at the tension again but it felt pretty tight.

 

[ColoJeep]

Belt looks fine and I've been driving the jeep regularly so don't think the battery is low. Will take a look at the tension again but it felt pretty tight.

If it stops squealing after it's hot and is quiet , the belt is loose or worn or both. I would try tightening it and or replacing it with a Gates "green stripe" belt.
I've had great luck with them over the years.

 

[tlobaugh]

Ok just started it again and getting the noise. The sound on the video doesn't do it justice on how bad it sounds.
For whatever reason, it won't let me post the video in this message so I uploaded a mp3.

 

[tlobaugh]

If it stops squealing after it's hot and is quiet , the belt is loose or worn or both. I would try tightening it and or replacing it with a Gates "green stripe" belt.
I've had great luck with them over the years.

Please listen to the mp3 I posted above and let me know what you think.. It doesn't sound like the squealing you normally get from a belt to me.

 

[ColoJeep]

Please listen to the mp3 I posted above and let me know what you think.. It doesn't sound like the squealing you normally get from a belt to me.

That sounds like a bearing to me , pull the belt off and spin each accessory to determine which one is bad.

 

[tlobaugh]

That sounds like a bearing to me , pull the belt off and spin each accessory to determine which one is bad.

I will give that a shot!

 

[Gilaguy23]

Cheapo harbor freight stethoscopes work great for pin pointing noises. If nothing else A long screw driver will work as well. One end on the suspected part and the other on the ear. Just dont slip

 

[tlobaugh]

So just an update here.

I got a new Gates belt which didn't have any changes, so I ordered a cheapo shorter belt for engines without ac. Once that came in I was able to bypass the ac pully and the sound definitely seemed to be coming from the alternator.

I ordered a cheapo alternator from Amazon (Sizzer brand, never heard of them but I plan to rebuild my Denso alternator anyways). Got that all installed and started it up and the sound was still there but not as bad and went away after about 1 minute. Hasn't made any more noise since and it's been a couple days.

Is it normal for an alernator to make noise on initial use??

 

[ColoJeep]

So just an update here.

I got a new Gates belt which didn't have any changes, so I ordered a cheapo shorter belt for engines without ac. Once that came in I was able to bypass the ac pully and the sound definitely seemed to be coming from the alternator.

I ordered a cheapo alternator from Amazon (Sizzer brand, never heard of them but I plan to rebuild my Denso alternator anyways). Got that all installed and started it up and the sound was still there but not as bad and went away after about 1 minute. Hasn't made any more noise since and it's been a couple days.

Is it normal for an alernator to make noise on initial use??

Not that i've seen , but weird things happen that are hard to diagnose.

 

[Stockli]

Bearings can do funny things