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Thread: Starter Troubleshooting

  1. #1

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    Default Starter Troubleshooting

    My PA-22-150 TP has stock starter and one year old Concorde battery that is kept on a charge minder. The battery voltage reads 12.9 VDC or higher when I go to crank cold. Procedure: Prime, carb rich, carb heat off, Master on, Left Mag only, "clear", crank and prop rotates about a half turn, comes up against compression and pauses a few milliseconds then rotates through quickly and starts, Mags to both. Wondering if starter has bushings, and if they need to be replaced. The starter electrical brushes were replaced about 50 hours ago - maybe 50 starts? I know this is not optimum, but I'm also wondering if it's relatively normal starting behavior? Yes, I can buy a new starter, and will do so for the weight savings at some point. Right now, just wondering how much insight you all may have to the failure mode(s) in stock starters. I'll clean my battery post terminals this weekend and see if it improves.

  2. #2

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    Default Re: Starter Motor spins slow then fast

    If you have a digital volt meter or one of the cancer stick lighter plug in volt meters to watch as you hit the starter, watch how far the drop is? If it drops below 10 volts during start I would send that battery back if its under warrenty. Have you tried another battery?

    On a side note, the lightweight starter I installed a month ago, the Kelly Aero, or Hartzell now, it is like God grabbing the prop and spinning it hard, its almost violent, hit the starter and it attacks the ring gear hard. It takes getting used to, I think I like the old low torque starter better.
    Last edited by PA-16; 12-20-2017 at 05:09 AM.

  3. #3

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    Default Re: Starter Motor spins slow then fast

    I started flying my Pacer when it was two years old. The stock starters when they were new would hesitate and you wondered if the engine was going to start, then it would turn it over and it started. I replaced the starter with a Sky-teck lite weight starter fourteen years ago and love it. My Pacer is a 1950 model but has a 0-290-D2 engine in it now.

  4. #4
    Administrator Steve Pierce's Avatar
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    Default Re: Starter Motor spins slow then fast

    Quote Originally Posted by Subsonic View Post
    Prime, carb rich, carb heat off, Master on, Left Mag only, "clear", crank and prop rotates about a half turn, comes up against compression and pauses a few milliseconds then rotates through quickly and starts
    My Super Cub does the same thing. A few years ago I installed a new Hawker battery in the stock location and a new 4 gauge battery cable per the chart on SkyTec's website. I have a Magnalite starter which has the common Bendix but a light weight motor that fits with the stock oil cooler mount. I also have a seperate ground wire other than the bonding strap Piper brazed to the engine mount. I finished the restoration of a pretty stock Super Cub last spring with a total time of 1000 hours. I replaced the original aluminum wire with 4 gauge cooper per a conversion chart and it would not turn over the engine with the spark plugs installed sufficiently enough to start the engine. I installed a SkyTec starter and it worked fine. I put my DC amp meter clamp around the starter cable and figured out the stock starter and my Magnaflite starter take twice the amperage to turn the engine over as does the SkyTec starter. My conclusion was that I should use a larger starter wire when installing a stock type starter.

    http://skytec.aero/starter-performance-issues/

  5. #5

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    Default Re: Starter Motor spins slow then fast

    Just my opinion but based on the available info it sounds like normal ops to me. There is a lot of inertia the starter must overcome to spin the engine. If it hits compression before the starter gets to speed... well, just imagine yourself pushing a load uphill with and without a running start. Even my Sky-tec starter stalls on the first blade sometimes. I just “bump” it through that compression stroke. The only piston airplane with electric start I can think of that hasn’t ever done it to me has a 24 volt battery with a geared starter turning an IO-520. The 12 volt version of that aircraft stalls the starter on every start.

    I am NOT saying it isn’t worth looking into, especially if this is a new development. Several years ago I had an aircraft get progressively worse until I burned out the starter. The culprit was a bad battery cable. The cable ends looked good so changing it was the last ditch effort after the battery and the starter.
    "Good judgement comes from experience, and experience comes from bad judgement." - Fred Brooks

  6. #6

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    Default Re: Starter Motor spins slow then fast

    Is the pause during start a new problem, or has it always did it? It could be the starter, read on Vans forum of same problem but with the LS skytec starters, the switch to NL model fixed it. http://www.vansairforce.com/communit...p?t-92332.html

    Seems like people like the Skytec NL, but before I spent $500. on a starter I would make sure your battery is strong first. I like the Kelly Hartzell 8012 starter, still new to me and feeling Torque-Effect as the starter grabs the ring gear is still a new sensation I am getting used to. I know people are saying very positive things about the Skytec but I think I would buy the Hartzell ERZ8012 over it for the one big reason, no shear pin to have to replace in a kickback event, the ERZ8012 has a different kickback protection that self resets.
    Last edited by PA-16; 12-20-2017 at 10:02 AM.

  7. #7
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    Default Re: Starter Motor spins slow then fast

    I switched to a skytech starter and heavy copper cables years ago and saw dramatic improvement in engine cranking. After I installed the Sutton exhaust, I got a field approval to install a Hawker battery on the firewall which greatly shortened my battery cables. I also put my switches on the panel. These changes also improved engine cranking.
    "You can only tie the record for flying low."

  8. #8

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    Default Re: Starter Motor spins slow then fast

    Quote Originally Posted by PA-16 View Post
    ...It could be the starter, read on Vans forum of same problem but with the LS skytec starters, the switch to NL model fixed it. http://www.vansairforce.com/communit...p?t-92332.html ...
    Good info. Mine is an LS so it may not have enough torque to overcome the compression (160hp O-320) from a standing start. I won’t swap it out just for that but it is something I will keep in mind if the LS fails.
    "Good judgement comes from experience, and experience comes from bad judgement." - Fred Brooks

  9. #9

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    Default Re: Starter Motor spins slow then fast

    Thanks everyone for the great insights. I'll first clean terminals then hook up my nice digital V-meter to watch voltage drop when cranking through, as per PA-16, to see if battery is putting out like a good one.

    Stephen's and Steve's comments are informative, suggesting the cables may not be carrying enough current even if the battery is good, even with stock starter. I'd like more info on the ground wire (return path), that Steve added to the Cub if he has a minute. What gauge return wire? Run from a starter mount bolt to ?

    I can tell my cables were changed from the original alu. to copper at some point, but nothing was annotated in my log book. I'm guessing they might have been done about 120 hours ago when the engine was rebuilt.

    Additional: After some research I see there's not a lot of margin in 12V aircraft electrical systems, especially compared with 24V systems. Hot rod car guys started putting 14V, then 16V batteries and reduction geared starters in years ago to crank big engines with lots of compression.

    Re: Aftermarket starters - I like the ERZ-8012, too. - bolts on without having to modify oil cooler mount, cut off casting bosses, change to longer cable, etc.. then there's the anti-kickback feature. Next would be the NL SkyTec.

  10. #10

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    Default Re: Starter Motor spins slow then fast

    One more question: Has anyone ever tried a heavier gauge battery cable on a stock starter as Steve suggested? Also, to answer: My initial starter pause has always been there, but gets worse in winter cold. Thanks for the help.

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