I understand the usual answer is the belt tensioner. But should it be tightened, loosened or replaced to eliminate squeal?
Well, you didn’t bother to tell us the model year or the odometer mileage of your Loyale, but if memory serves me correctly, these cars haven’t been made for…somewhere around 14 years.
With that in mind–Has the belt tensioner ever been replaced?
If not, then it has likely lost a lot of its tension.
So, the answer–usually–is to first check the belt tensioner’s condition. If it is still able to maintain tension, then simply adjust (tighten) the belt tension. If it is not in decent condition, then replace the tensioner.
Also, consider that a belt that is “glazed” can be the source of this noise.
How old is the belt, and what kind of condition is it in?
Remove the belt. Spin all the pulley’s with your hand. One of them is likely to be rough and a little loose on it’s shaft or it won’t turn at all. That’s the one to replace. You might as well spring for a new belt too…
Is the noise constant or just periodic, such as when you start the engine or during acceleration (I use the term “acceleration” loosely).
I’m pretty sure the belt tension on your Loyale is manually adjustable. If the belt is worn and slipping you should install a new belt and adjust the tension. That should eliminate the noise.
If the bearings in one of the pulleys are going bad you must replace the pulley in question.