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Very hot alternator

  • 25-08-2010 8:22pm
    #1
    mustang68
    Registered Users, Registered Users 2 Posts: 1,119 ✭✭✭


    Hi,

    I had a flat battery from not using the Mustang for a while and I jumped it tonight, started fine, ran quite happily. I was changing the belts. When I cut off the engine after about 20 mins I accidentally touched the hub of the alt (which is about a year old with not much use) and it nearly burnt the finger off me :eek:

    I don't think it should get this hot, but I'm wondering would it have been particularly taxed with charging a flat battery, or is there something else wrong?

    thanks


Comments

  • #2
    jimmyw
    Registered Users, Registered Users 2 Posts: 3,382 ✭✭✭jimmyw


    Spin the alt pulley with the belt off and see if its free to turn.Could also be the belt slipping on the pulley cause of seizure of a bearing maybe


  • #3
    mustang68
    Registered Users, Registered Users 2 Posts: 1,119 ✭✭✭mustang68


    jimmyw wrote: »
    Spin the alt pulley with the belt off and see if its free to turn.Could also be the belt slipping on the pulley cause of seizure of a bearing maybe

    I will indeed, I took it to work today and it seemed like it wasn't hot enough to strip the flesh from my finger like last night, just a "bit hot", although that might be because of airflow when driving.


  • #4
    jimmyw
    Registered Users, Registered Users 2 Posts: 3,382 ✭✭✭jimmyw


    Has it got a fan on it by any chance? It should not be getting this hot whether the car is moving or not.I would still guess its a bearing.Might be an idea to remove it (if you can) and get it checked out.


  • #5
    mustang68
    Registered Users, Registered Users 2 Posts: 1,119 ✭✭✭mustang68


    jimmyw wrote: »
    Has it got a fan on it by any chance? It should not be getting this hot whether the car is moving or not.I would still guess its a bearing.Might be an idea to remove it (if you can) and get it checked out.

    yep it has the usual fins on the pully, unfortunately it is in the direct airflow of the rad., I really hope it keeps together as it's going to be my wedding car in a week!! I'll check the movement of it tonight, any resistance would indicate a (very new) bearing gone.


  • #6
    jimmyw
    Registered Users, Registered Users 2 Posts: 3,382 ✭✭✭jimmyw


    I would have thought that been in the path of the rad should actually help it seeing that the rad fan or a/c fan would be on and so increase the airflow.It could well be an electrical fault with the diodes for example.I have seen on another car that the battery was been drained because of faulty diodes, and this car was laid up too.Best to get it checked out I would say.


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  • #7
    Fishtits
    Closed Accounts Posts: 1,382 ✭✭✭Fishtits


    Its not unusual for the alternator to get hot charging a flat battery - its running at or near max output. I would doubt you actually have a fault with yours, it should behave normally once the battery comes up.

    Its always better to bench charge a battery for this reason. There is one particular Japanese 4x4 (begins with P...) that is notorious for burning out alternators in this scenario.


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