The belt on my car continues to squeak. I have found that spraying WD-40 on it stops it for a while, but is a short-term fix. I changed the belt, and it stopped for about 2 weeks, but now it is squeaking again. It’s pretty loud and is pretty much constant while it is running. Could it be something else? Hopefully some of you Auto-Gurus out there can give me suggestions. Thanks.
If you’ve replaced the belt and it still squeaks, I’d check all the mechanical bits driven by the belt: pulleys, tensioners, accessories (a/c, water pump, etc).
Also, make sure the belt’s tension is correctly set.
Who told you to spray WD-40 on a rubber belt? Augh! you have something wrong and the belt is slipping because of it.
Your belt is making an awful noise because it is slipping. When you spray WD-40 onto it, you make the symptoms go away, but you make the problem much worse.
Belts slip because (1) they are worn out or (2) they aren’t on tight enough or (3) the thing they are turning is busted and therefore harder to turn which makes them slip. Since you replaced the belt we can rule out a worn belt, and since the problem went away for 2 weeks it’s probably not a busted part. I’m guessing that you didn’t get the belt tight enough when you put it on. Put some more elbow grease on tightening it up and you should be fine.
And keep the WD-40 away from your belts.
Hey Padeye, they tell you to spray WD40 on things that make noise. I’m surprised that people don’t spray it on their kids and/or spouses! 
Thanks for the inputs. O.K. I won’t spray any WD-40 on the new belt. In the past the power steering pump has “moaned” a bit when turning. Maybe the pump is not working at 100% and the pulley is harder to turn therefore slipping on the belt. If I take the belt off and spin the pulleys by hand, should I feel resistance if one of the pulleys is slipping? Also, when I purchased the belt, I got the cheaper one (about $20 difference). Could it be just a cheap belt? Also, it is a spring-loaded tension which automatically expands the belt tight. Thanks.
Until you get the time to fix the root cause, hold* a bar of soap against the side of the belt that contacts the pulleys while the belt is moving, to put a coating of soap on the belt. That should quiet it down, and it won’t hurt the belt. The soap will eventually wear off.
*Carefully!!
As has been said, WD40 or any oil on the belt will not fix it. In fact, it will ruin it.
At this point replace it.
In the future, you could try a spray called belt dressing. It’s a spray that you can get at Auto stores. It’s a temporary fix.
Another trick you can try. A piece of copper pipe, or even a VERY big screw driver when placed against the alternator or other belt driven accessory on your car with the other end placed at your ear can sometimes tell you where the noise is coming from. Like a stethoscope.
Be VERY careful. NO loose clothing and all that.
How is the fluid level in the power steering pump?
I think your pump is ‘moaning’ because it is stressed out. :). Seriously. Are you turning the wheels when the car is not moving?
It is best if the car is moving before you turn the steering wheel. If the car is stopped with the brakes on and you try to spin the steering wheel you are asking for a lot from the power steering pump.
When I say let the car move when you turn the steering wheel, I’m talking inches. This will take a tremendous amount of pressure off the pump. As a rule, don’t turn your steering wheel unless the car is moving .
The most common cause of belt squeal is looseness. It’s possible that the belt tensioner is weak or stiff, preventing it from applying proper tension. If that’s the case, the cure is to replace the tensioner assembly.
Old/worn belts get glazed and don’t develop enough friction. Obviously not the case now.
Occasionally a new belt is faulty and squeals. It’s not common, but it does happen. This is perhaps more likely with the budget-priced belt.
There’s some chance that there’s still some WD-40 residue in the pulleys, which contaminated the new belt. It might not be a bad idea to remove the belt and clean all of the surfaces it contacts with spray brake parts cleaner. Rotate the pulleys by hand to get them clean all the way around. You could also spray the belt surface with brake cleaner and try it again. If it’s still noisy, a new belt and/or belt tensioner will be needed.
Note on the preceding paragraph: Power steering pumps will have noticeable resistance when turned by hand. As long as it can be turned by hand without great effort, and turns smoothly, it is okay. Alternators and water pumps will have light resistance. They should turn smoothly. Air conditioner clutch pulleys should spin freely and smoothly. Idler pulleys and tensioner pulleys should either spin freely or with very light resistance (and of course, smoothly). The crankshaft pulley, at the bottom center of the engine, requires significant effort to turn with a wrench.
Spraying a light quick touch of WD-40 on a belt is a good test to confirm that it is indeed the belt making noise. The noise will stop for a short while. As mentioned by others, it’s not a reliable way to solve the noise problem.
Belt dressing is really a temporary fix, and the problem will eventually get worse.
What you need to do is clean the pulleys and belt - there’s probably enough dirt and oil built up on them that they arent getting the grip they need.
I usually get a new belt, and take the old one off.
I then clean off the pulleys - a clean rag wetted with isopropyl alcohol or acetone (wear gloves for either), and I’ll scrub the pulley grooves with it to get all the gunk out - you’ll notice a lot being pulled off.
Remount the new belt, make sure it’s the right tension (if it’s not tensioned automatically by a sprung pulley), and enjoy quiet belts again.
-Jeff