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Engine belt issues (noise)

Hi. I was wondering if someone could give me some idea about my car problem. its a 1999 dodge ram and in summer it runs fine but in winter when it gets cold the belt is squealing very loud. Even after the engine warms up, the noise is there. The belt seems to be OK and I cannot see it moving anywhere (Or maybe I don’t have an eye for it).

Any suggestions?


Sounds like one of the pulleys is going out.
If it has a serpentine belt, I’d guess the tensioner.
Someone is going to have to take a hands-on look-see.

For the record, until a belt gets bad enough to start cracking in in its ribs, you can’t tell for certain if it’s okay visually. How old IS the belt?

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Place a wrench on the belt tensioner and see if it rotates back and forth smoothly.

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I agree with Nevada. I think you will find the tensioner is frozen.

Thanks. Where roughly is the tensioner? (I dont know how old the belt is, I bought the truck 5 years ago)

I think yours will be a smooth pulley, attached to a spring loaded arm about 6" long (you won’t see the spring). Some also have the ribs for the belt, but they are still attached to an arm.

It does sound like a tensioner or idler to me also. I had an intermittant low pitched noise occasionally on my old Blazer and recently decided to isolate it and narrowed it down to the tensioner pulley using a stethoscope. Despite the pulley remaining straight and the belt tracking straight on it, when turned in my hand the rough ballsy rotation was obvious. When those pulleys go out they usually leave you stranded.

And a mechanics stethoscope is a must have for DIYers in my opinion.

shows what the typical fan belt tensioner looks like.

Squeals when it is colder are a pretty common thing. The belt is made of a material that shrinks the warmer it gets, so it is longest and more likely to slip when cold. Anything in the belt path tho can make a squealing noise, either b/c the belt is slipping on the pulley, or the pulley’s or accessory’s bearings are worn. You can experiment to see if it is related to an accessory. Does it change when monkeying with the AC controls (A/C compressor)? When you turn the steering wheel (power steering pump)? When you turn on the headlights to bright (alternator)?

The automatic belt tensioner is below the alternator.