New belt squeal

[aculverwell]

I recently replaced the serpentine belt on my Volvo D4-300-- and it now squeals for a few moments after I start the engine. It eventually quiets down, but I do see some black belt dust in the engine compartment. I re-tightened the belt (harder) one time and it seemed to get a bit better, but I am concerned about overtightening. Sadly, I can't tell if I need to tighten it more, or loosen it (yes, I don't have a torque wrench). So, is a squeal a symptom of a too loose belt, or a too tight belt? Thanks Team!

 

[lproulx]

Squealing usually means too loose. The belt slips on the pulleys and makes the noise. The reason it often quiets down is that the alternator has to put out a lot of current right after starting to replenish the starting battery. then the noise stops when the load goes down. I would try deflecting the belts with your fingers between two pulleys to get an idea of how tight it is. Check all over the tensioning arrangements to see if anything is stuck or abnormal. It may seem silly, but you may have the wrong belt. I once spent two hours trying to install a serpentine belt on my car and went hat in hand to a repair shop and they couldn't install it either. They had to get a longer belt. It may have been mis-packaged or mis-made.

Larry

 

[Ralf H]

Hi lproulx,

aculverwell is right. A squeaky belt usually implies that the belt is a bit loose. That's also why you could be seeing the belt dust as well (other reasons being a pulley out of alignment, etc.) The best thing to do would be to check your engine manual for the belt tension specs and tighten it according to those. If you still have issues at that point, it might be a good idea to let your dealer have a look for further diagnosis. Hope this helps.

Cheers,

Ralf

 

[BB marine]

A new belt will require proper adjustment to confirm it is tight and adjusted to factory specifications. There is a easy procedure for proper adjustment. The tensioner roller has a square drive insert. Using a torque wrench with the belt installed torque the adjustment tensioner to 70NM or 52 ft lbs. While holding that torque adjustment tighten the belt adjustment mounting bolts to hold the position. The final torque on the mounting bolts is 35 to 40 ftlbs. After adjusting the tension confirm a good belt seat on the pulleys. Confirm that there is good tension and a small amount of deflection when pushing down on the belt. Operate the engine for about 10 hours and check belt tension again. A new belt will stretch. The correct belt properly adjusted should not squeal.