Tightening a loose serpentine belt

Maintenance/Repairs
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Actually above + an interesting mystery.. Late last spring I began hearing a noise of constant pitch (sounding like someone sanding wood) when the engine was cold—Louder when it was colder/cooler. As the engine warmed up the noise went away. Throughout the summer,No Noise. n. Late summer broken water pump replaced along with hoses/belts. No noise until, temps in AM in the 40’s; Now that same damn noise is back.
Only LOUDER! Same pattern>>as engine warms noise softens and goes away. My ear suggests noise is coming from the tensioner pulley (But, I’ve been fooled before)
As to the question above, Do I tighten the belt on ‘This vehicle’ using the tensioner pulley or do I have to use the “Pry the Alternator forward” method.?

One last thing, while the noise is occuring it does get louder with acceleration but is soon blocked out by normal engine noise.
Please HELP!

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More than likely the tensioner needs to be replaced.

The tensioner automatically applies tension to the belt using a coil spring.

And with any spring metal, temperature effects how much tension the spring applies to the tensioner.

Tester

2 Likes
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Agreed. And you may want to consider any idler pulleys as well.

1 Like
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Thanks for getting back to me…And so fast.
Didn’t want to make description overly long; But today I put pressure on the tensioner pulley and noise appeared to be softer. Then again, it was 70 degrees.

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And thank you for your input Mr. Knuckles.

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Sometimes you can narrow down the noise source by using a length of old garden hose as a sort of stethoscope. There’s so many moving parts in an engine no telling what’s the culprit without having a shop tech actually looking and listening when it is happening.