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1987 mgm battery size, diagnosing and fixing no crank

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    1987 mgm battery size, diagnosing and fixing no crank

    The 1987 MGM suddenly won't crank, and won't click the solenoid. Jumping with cables produces no change. So I pulled the battery.
    One store reports the battery at 12.6 volts, 89% charged, but bad, won't take a charge, needs a replacement. The current battery is size 24. They recommend size 56. Another store says direct replacement is 64.
    Suggestions?
    1987 Grand Marquis LS two door, trying to get to the 60,000 mile mark.

    #2
    Group 56 is the standard battery with small alternator. 64 is for heavy duty (police package) with 100 amp alternator. Cars with the heated windshield also came with a group 64 battery.
    89 Colony Park
    90 Colony Park
    70 HEMI Daytona Convertible

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      #3
      The 2nd store tested and reported good battery. They charged it, and tested it the next day. I installed and tested with the lights, dash lights run, and clock, all ok. A crank attempt killed all other electrics, which returned sometime afterward. If I had to guess, I thinking a short in the starter or solenoid that reduces voltage too. Suggestions?
      1987 Grand Marquis LS two door, trying to get to the 60,000 mile mark.

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        #4
        the crank cutting things out is a breaker going, usually caused by a bad connection. Take a file, or some emery cloth to every connection near the battery, especially around the starter solenoid on the fender.

        85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
        160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
        waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

        06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

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          #5
          I upgraded to a more powerfull battery, but I don't remember the group number. I can get it after work. I also picked one with the POS and NEG reversed. I didn't like the idea of the POS side so close the the fender/ground.


          sigpic

          I'd rather be a failure at something I love than a success at something I hate.
          George Burns

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            #6
            65 series battery works on an 88 or newer model from the factory. Heck the 2011s use s 65 series.

            I put a 65 series in my 87, it works just fine. The hold down well...that doesn't hold any more.
            -Nick M.
            Columbia, SC

            66 Squire, 89 Colony Park, 90 TC, 03 TC, 06 TC, 07 TC (2x)
            03 BMW 540iT, 07 Toyota Tundra SR5 Dbl Cab/5.7 2WD

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              #7
              Bobby has a "65" in his 87 GM. He used a dremel to trim down the "ridge" in the battery support and all is well. There is no hold down but the battery is so heavy and wedged in well so there has not been a problem.

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                #8
                Seems to me functional hold downs are unobtainium. I never see those at yards.
                1985 LTD Crown Victoria - SOLD
                1988 Town Car Signature - Current Party Barge

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                  #9
                  There are generic ones but not sure how good they are.

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                    #10
                    I use some in between size in the 88 since the hold downs were crap in that one and I just put in a generic battery tray and J hooks.

                    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
                    Originally posted by gadget73
                    ... and it should all work like magic and unicorns and stuff.
                    Originally posted by dmccaig
                    Overhead, some poor bastards are flying in airplanes.

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                      #11
                      You may have bad battery clamps lose conections.

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                        #12
                        I bought a 34. It has 800 cold cranking amps. It's an AutoCraft from Advanced Auto.


                        sigpic

                        I'd rather be a failure at something I love than a success at something I hate.
                        George Burns

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                          #13
                          John, after ignition switch > run, I jumped the solenoid with a screwdriver, and got a small spark, no crank, and all other electrics stopped. After removing the battery negative terminal, waiting a few hours, and reconnecting the neg. terminal, electrics are ok, until I tried a switch > start, and the change was some clicking, along with no crank, and dead electrics. Where would I find a breaker that might be tripping and then eventually resetting?
                          1987 Grand Marquis LS two door, trying to get to the 60,000 mile mark.

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                            #14
                            that sounds like weak battery to me. If the terminals are on the battery good and tight, I'd suspect the battery at this point. The other problem could be bad terminals or bad contact to the frame/starter.

                            Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                            rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
                            Originally posted by gadget73
                            ... and it should all work like magic and unicorns and stuff.
                            Originally posted by dmccaig
                            Overhead, some poor bastards are flying in airplanes.

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                              #15
                              I'm trying again to crank. The battery has been replaced with this one for $105 plus tax:
                              AutoCraft Silver Battery, Group Size 56, 550 CCA
                              56-1 Warranty: 2 YR FREE REPLACEMENT

                              A start try immediately trips a circuit breaker, that resets after I disconnect and reconnect the battery negative terminal. My voltmeter died, so I'll get one tomorrow, disconnect the fat starter cable from the relay, and see if I get 12 volts at the relay output terminal when my associate tries the ignition > start. If so, does that indicate a possible short in the solenoid, starter or its cable? If the circuit breaker trips upon switch > start with no grounding from the relay output, does that point to a short in the ignition > neutral > relay input circuit?
                              1987 Grand Marquis LS two door, trying to get to the 60,000 mile mark.

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