Loud Squealing Noise

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Sep 28, 2015 | 04:30 PM

mwoj

Thread Starter

Laughing Gas

Joined: May 2015

Posts: 931

Likes: 392

From: Port Orchard, WA

Loud Squealing Noise

Hi all, I'm having some issues with my truck. It's a '75 F250 with a 360. Not too long ago, it started making an incredibly loud squealing noise upon startup. It only lasts for about 3-5 seconds and then goes away. I've already replaced the belts and the water pump. My power steering pump started blowing fluid awhile ago so I think that it might be the power steering pump. Any guesses? Thanks.

Sep 28, 2015 | 04:34 PM

HIO Silver

Fleet Owner

Joined: Dec 2009

Posts: 20,678

Likes: 82

From: NorCal

'Sounds like a loose belt to me... double-check your belt tension and roughing up the pulley groove with sand paper while observing all proper safety precautions.

Sep 28, 2015 | 04:39 PM

mwoj

Thread Starter

Laughing Gas

Joined: May 2015

Posts: 931

Likes: 392

From: Port Orchard, WA

Quote:

Originally Posted by HIO Silver

'Sounds like a loose belt to me... double-check your belt tension and roughing up the pulley groove with sand paper while observing all proper safety precautions.

How tight should they be? I tightened them pretty tight and the noise still occurred.

EDIT: I pulled off the belts one at a time and it turns out that it's the alternator that's making all the noise. Also, make sure to disconect your battery before you slide the alternator towards the block. I just got a nice little firework display.

Sep 30, 2015 | 12:39 PM

kaden78ford390

New User

Joined: Sep 2015

Posts: 15

Likes: 0

My truck had the same noise, I found it to be a vacuum leak on the back side of the block and a vacuum cap later and it no longer squeals, perhaps it could be the same situation with yours

Sep 30, 2015 | 02:47 PM

HIO Silver

Fleet Owner

Joined: Dec 2009

Posts: 20,678

Likes: 82

From: NorCal

Quote:

Originally Posted by mwoj

Just to answer your question, place a straight edge across the longest part of the belt between two pulleys and depress. I like to have no more than 3/4-inch of deflection with "medium" pressure

Sep 30, 2015 | 04:58 PM

ultraranger

Lead Driver

Joined: Apr 2011

Posts: 6,399

Likes: 40

From: El Dorado, Arkansas

Squealing alternator could be the belt or, it could be the alternator bearings going out.

If it's the alternator itself and needs to be replaced or, new bearings put in, now would be a good time to upgrade to a Ford 3G alternator.