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Any help...I’m out of ideas.

Alternator issue, getting too hot to touch. Any help would this would be greatly appreciated:

  1. Wiring as is, (alternator neg grounded to engine, positive to starter, starter to battery isolator which can then select which battery to charge) alternator gets very hot when engine running.

    • when connected (via switching isolator switch) to starter battery, voltage reads 14.6v consistently. (Starter is a 90ah car battery, lead aside) alternator still hot.
    • when connected to house bank (4x Trojan 6v lead acid) reads between 13.6 and 13.8v. Amps in reads between 65-74Amps. (Alternator is a 105Amp I believe)
    • engine starts and runs fine.
  2. @ rest, depending on state of charge, starter reads 12.6v, house read between 12.3-12.6v depending on charge.

What I have done so far:

  1. Replaced Alternator, from a 60Amp new (was exhibiting similar issues) to this current new one. Both heat up, just to hot to touch, guessing 120 degrees C.
  2. Replaced both + and - wires from alternator to ground/starter. Same issue.
  3. Cleaned grounds on engine. Same issue.
  4. Took + straight from alternator to house bank, bypassing all other wiring, so alternator connected to ground, positive to positive connection on house bank. Same issue.
    • when I checked voltage @ alternator, it reads 13.99v, when I check @ battery bank, between 13.6 and 13.8v.
  5. Ensured belt is very tight.
  6. Ensured all bolts are very tight.
  • 1
    Welcome to Motor Vehicle Maintenance & Repair! What is the vehicle in question? Year/make/model/engine? – Pᴀᴜʟsᴛᴇʀ2 Apr 18 '19 at 22:34
  • Has the cooling fan been removed ? perhaps to get the pulleys to line up? – Solar Mike Apr 19 '19 at 5:51
  • Alternators do get hot. How do you know your case is special? – mike65535 Apr 19 '19 at 13:01
  • I don’t, I just wasn’t sure it should heat up quickly and then stay hot, even if the battery is sat at 14.6v. – Nick Creak Apr 19 '19 at 23:03
  • What temps are normal? Also it does have a fan also belt is VERY slightly off at one angle, maybe 1-2mm out across the short stretch – Nick Creak Apr 19 '19 at 23:05

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