How To – Curing Alternator And Accessory Belt Squealing

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    We have all experienced it or heard someone driving down the street with a squealing belt on their engine but what causes this and what can you do about it?

    Your engine is the mains source of power for your car. Along with powering your wheels to get you down the road accessory belts run from your crankshaft to power things like your Air Conditioner, Power Steering and Alternator.

    The squealing that you hear is the belts slipping on the pulleys. When your belts slip and squeal it means some of the power they need to work is not being transferred and this can make your accessories not work correctly.  For instance one of the first things you look for when diagnosing a poorly charging battery is a loose Alternator belt. If the belt is really loose it will squeal.

    Other reasons your belts can squeal is when they get older and the rubber material hardens and glazes over. If your belts are squealing or if you see them getting shiny surfaces on the inside area that comes in to contact with the pulley groves then you will need to replace them.

    A small amount of oil or moisture on the belt can cause it to slip and if it slips long enough it can cause glazing of the belt just like what happens when the rubber gets old and hardens.

    Do All Squealing Belts Need To Be Replaced?

    Not every squealing belt needs to be replaced but if the belt is shiny, smells burnt or is fraying on the edges it usually means the belt is nearing the end of its life.

    If you have just performed work on your vehicle or if you have just cleaned the engine or drove through deep water then the belt squealing can be cured by cleaning the belt and allowing it to dry.

    Cleaning Your Belts

    If you think you may have got oil or other liquids like antifreeze on your belt you should clean it as soon as possible.  You can use a carburetor / injector cleaner to get oil off the belt or soap to get antifreeze or other liquids off the belt.

    Once the belt is clean and dry and you have repaired whatever was leaking then you can run your car as normal.

    Belt Dressing can be sprayed on a squealing belt to restore some of the adhesion and stop the squealing but a clean belt that is properly tightened should not squeal.

    You never want to sand or scrape the belt surface.

    Replacing Accessory Belts

    Single serpentine belts can be rather expensive and may require a professional to install but standard accessory belts can be installed by most people with a few hand tools.

    If you don’t feel up to changing the belt yourself some auto parts places may actually do it for free or a nominal charge. If not then any local mechanic that you trust should be able to get the job done in about 30 minutes.

    Final Note

    Squealing belts that are not due to you running through a puddle or cleaning your engine are an indication of wear and should be inspected and possibly replaced. Normally the squealing will start when you start your car cold  in the morning and then it will progress to squealing whenever you apply the gas.

    Because this is relatively easy to fix and somewhat inexpensive if you know the belt is more then a couple years old don’t guess just replace it. It may also be a good idea to replace all of your belts at the same time.

    When you do replace your belts keep the old ones for emergency reasons in the trunk of your car. Put them in with the spare tire and they won’t take up space but they will be there if you break down someplace far from home or help. An old worn belt is better then no belt especially if its your power steering or alternator belt.

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