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Thread: slow crank.

  1. #11
    Gilbert Pierce's Avatar
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    Default Re: slow crank.

    Its one of three things:
    Weak battery
    Weak starter
    Bad connection: cables or solenoid.

    After starting or trying to start feel each connection between the battery and the starter. A hot connection indicates a high resistance connection.

  2. #12
    Stephen's Avatar
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    Default Re: slow crank.

    You can also do a voltage drop test. Check voltage difference on each side of a connection. The difference should be less to .5 volts. Also, check voltage drop over the length of your cables. Too much voltage drop means too much resistance.

    You can also make a simple check on your battery with a volt meter. It should read 12+ volts. Continue the check and add amperage draw, turn on landing lights, radios etc. Then watch your voltage for about 30 seconds if you have significant drop you have a weak battery.

    I have copper cables, high crank light weight starter and Earth X battery and I get strong engine cranking speed.
    "You can only tie the record for flying low."

  3. #13
    Stephen's Avatar
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    Default Re: slow crank.

    Quote Originally Posted by Stephen View Post
    You can also do a voltage drop test. Check voltage difference on each side of a connection. The difference should be less to .5 volts. Also, check voltage drop over the length of your cables. Too much voltage drop means too much resistance.

    You can also make a simple check on your battery with a volt meter. It should read 12+ volts. Continue the check and add amperage draw, turn on landing lights, radios etc. Then watch your voltage for about 30 seconds if you have significant drop you have a weak battery.

    I have copper cables, high crank light weight starter and Earth X battery and I get strong engine cranking speed.
    Don't forget to check voltage drop between the battery terminal and the battery cable.
    "You can only tie the record for flying low."

  4. #14

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    Default Re: slow crank.

    Quote Originally Posted by CamTom12 View Post
    I added a 2 wide braided ground strap from my block to my battery.

    I also run an earthX battery, and I can almost taxi with my starter.
    This was basically what I was asking about. If you ran straight from your battery to the block would bypass much of the starter/engine/engine mount/frame/negative battery cable connections. You have starter/engine/negative battery with your set-up. I do know I have excessive voltage drop in the system and was questioning of people were adding a proper ground as a way to address what seems to be a common issue. I am hoping to have some time this weekend to do a little more testing to see if I can pin this issue down.

  5. #15
    walt.buskey's Avatar
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    Default Re: slow crank.

    OK, for/in the FWIW department: The ground cable on my tractor broke. It was a 1/2" braided cable and was apparently, on the model I have, just too short from the factory; its three-cylinder diesel did its thing over five years, gradually vibrating enough to break the strands, one by one. (Of course the final strand broke during a major snow storm!)

    After finally figuring out why everything electrical besides the starter worked, I replaced that cable, and then added a SECOND ground cable on the other side of the block, for "insurance."

    My tractor, a 2007 Massey-Ferguson GC2310, is STILL working just fine on its original battery. After replacing the broken ground cable (and adding the second one), it cranked (and started) like it was new. What a difference. Lesson learned.

    Not sure about airplanes, but that ground connection is important! A typical 12-volt starter needs to be able to have access to a boatload of amps to work properly; don't see why a second ground connection, besides adding a bit of weight, could only help.

    Other opinions?

    PS: When I did the Bogart battery box mod for a smaller AGM battery on my PA-22, I also replaced the last aluminum cable with one of Bogart's copper ones. Money in the bank.

  6. #16

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    Default Re: slow crank.

    I dropped my pacer at the shop yesterday for this very issue. Since the engine swap I have been battling this and of course, the first thing I did was replace the battery as I was not sure how long the "old" battery had been in it. Worked great the first start or two then I would just get the clicking / machine gun buzz out of it when I hit the start button. Hooked the earthx jump pack up and it would start. Last week even the earthx jump pack did nothing for me. Battery at rest was 12.6 volts. Pulled the battery and took it home to charge anyways. After about 5 minutes on the charger it said it was topped off. Took it back to the plane and low and behold it ripped right over. I had checked connection at the plane before pulling the battery (took the cables off, made sure they were clean and reinstalled).
    Second thought was the new voltage regulator needed to be "turned up" to get proper voltage to recharge the battery. I left the trusty volt meter hooked up for the quick flight to the hangar and even running the strobes, nav and both landing and taxi lights the voltage was rock steady at 14.6.
    I am guessing a bad connection somewhere along the line has been plaguing me, hopefully the guys will get it figured out and I will post what they find.

  7. #17

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    Default Re: slow crank.

    new master, battery wires to do away with the old braided cables and multiple connections, new solenoid.. still crappy cranking. New starter and she is ripping again. spent a lot of money trying to not spend much LOL.

    I brought the old skytech light weight starter home and pulled it apart. I think the issue was the one way bearing or cam on the gear, it was real dry and slipping on the shaft. I cleaned it up and it seems to be throwing out fine and I will try it on another engine on the stand at some point in time before I declare it a good spare.

  8. #18
    Glen Geller's Avatar
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    Default Re: slow crank.

    Quote Originally Posted by akflyer View Post
    I dropped my pacer at the shop yesterday for this very issue. Since the engine swap I have been battling this ...
    Engine swap?
    Freshly painted engine, and maybe the mount?
    Paint where the starter bolts to the engine?
    Braided ground strap from engine mount not connected to the crankcase, or paint at the contact point?
    Somewhere you have a poor ground, and I would bet its to do with the grounding and the primary variable you mentioned is rebuilt engine.

    Good luck,
    GG
    Glen Geller
    1955 PA22-150 "One For Papa!"

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