Serpentine belt squeal, need to know how to tighten

If the squeal is mechanical (belt slipping) and you have a serpentine belt, either your tensioner is not functioning properly, or the belt has stretched to the point where the tensioner cannot keep proper tension. If you don't have a serpentine belt, tighten the belt using the appropriate adjuster.
If the squeal is air in the lines (more of a buzzing sound that you can sometimes feel in the steering wheel), you need to service the fluid reservoir, and it will take a little while for all the air to work out of the system.

Check codes and since they screwed up they should run the check for free.


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If you have an manual adjuster you need to tighten or replace the belt, belt treatment may help.
If you have an automatic adjuster. You can try belt treatment, if it doesn't work you'll need to replace the belt and maybe the adjuster.

the belt is self adjusted by a spring loaded automatic belt tensioner, if the belt is noisy or seems loose either the belt size is wrong (if it was replaced recently) or the tensioner is defective or one of the belt idler pulleys is defective.

If you have a serpentine belt it is self adjusting. You may need a new belt or maybe you have a bearing going out in the alt, A/C pump ect.

It should not require any adjustment. the right tension is provided by the idler pully. If you want to release the tension for serpentine removal or examination release the tension on the idler pulley in the rear of the motor, spin the nut in the center like you were tightening, and the pressure will be released from the serpentine belt. Reversely, the appropriate tension will be given using the same way when the strap is reinstalled.
Dan

If it is a serpentine belt is is self adjusting. So if it is squealing then it needs replacing as it is worn out. And also possibly the tensioner needs replacing as it may not be holding sufficient tension on the belt. If it is a drive belt it more than likely still needs replacing as it will have become glazed from slipping. On a drive belt it is adjusted by loosening the mounting bracket on the A/C and moving it in a direction that tightens the belt.

Typically serpentine belts are tightened automatically by a tensioner, if the belt is slipping, or squealing, try installing a new belt, careful of the routing tho, be sure to install it correctly, or more problems may occur.

Shortly after replacing the serpentine belt in my lancer, the same thing happened. It is NOT the timing belt. Belts squeal when they slip. If your timing belt slipped it would cause your car to run funny.

have somebody check the belt for wear (or do it yourself), replace if necessary. If it doesn't need replacement, just tighten it.

If you have the 4cyl engine that I have, the tightening is kind of a pain in the ****. Not a great design by mitsubishi. There's a pulley near the front right corner of the engine in front of the alternator. the belt should be running around this pulley GROOVE SIDE OUT. This is the tension pulley.

To tighten:
1) Lightly loosen the bolt in the center of the pulley (slightly loosen, DO NOT REMOVE).
2) Under that pulley there's another bolt. You can see that the bolt goes through a piece of metal
attached to the back of the pulley. Figure out which way you need to turn the bolt to move the
pulley toward the front of the car. (i don't remember if it's right hand thread, or left hand) This
puts extra tension on the belt. You probably don't need much. Over tensioning the belt can
cause pulley bearing failure. If you haven't done this work before, ask someone for
help. It's better to tighten a little bit, a few times rather than overtighten once.
3) Don't forget to ReTighten the bolt in the center of the pulley.

If there's lots of cracks and pieces missing on the ribs or grooves of the belt you should replace it first.

Happy repairing,
Cliff

The noise is most likely the serpentine belt. Check it's condition and that of the belt tensioner. It sounds like the belt is slipping, causing the squealing noise u describe. As the belt warms up, it's getting a better 'grip' and the noise stops. Turning on the heat also turns on the a/c in newer cars, this added drag on the belt (one more component to turn, the a/c compressor) would explain why it happens when u turn on the heat. Is the belt original? If yes, it's time to change it, and check the belt tensioner to make sure it's doing it's job of keeping the belt snug on all the pulleys. Let me know how u make out.