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Thread: Slow starter

  1. #1

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    Default Slow starter

    Well, on one unfortunate day, my starter just decided it was going to start turning with significantly less authority. It got so bad, in fact, that in order for it to turn at all, I had to turn the magnetos off, and then once it got some inertia, I'd flip them back on and it would fire. I had an old gill battery that was giving up the ghost, so it was my first priority. I replaced it with a concord, but it didn't fix the issue. My mechanic then suggested to put in a skytec starter. I've been wanting to seal the cowl where the old starter poked through anyway, so we installed the skytec, hoping that was the issue. It was not.

    Rather than pay $100/hr for further diagnosis, i stated to dig. I found that the starter relay was a continuous duty model, not rated for the amps of starting. I replaced this and tore apart the old relay to find substantial arc pocks on the plunger disc and the stationary contacts. I thought for sure this was it now. No such luck! So I got out a set of jumper cables and connected one end to the battery positive and the other to the starter. It seemed to spin reasonably fast if I pressed the starter button AND had the jumper on the +terminal. So heck, maybe it's the + cable that's corroded. I replaced that. No good still. I'm just about out of ideas.

    I went to take another close look, and now I'm wondering about the - side, but I'm tired of throwing money at it, and my mechanic doesn't really seem to have any ideas either other than what we've been doing. So here's my issue. The negative cable from the battery connects directly to the seat support on the airframe. It's a good connection, but it's an airframe ground. I can't find and engine bonding strap anywhere on the plane, so I'm wondering how the engine is getting its ground returned? All I can think of is the throttle and mixture cables, as id expect the engine mount to not conduct through its rubber bushings (unless it just grounds through the bolt). Is it possible that a simple bonding strap is needed? That one day whatever ground connection the engine had, finally got rough enough and won't let enough amps pass for start? Or do I have some deeper engine problem that's causing excessive drag? Where is the bonding strap attached on your planes?

    I'm going to go out again tomorrow and attach the jumper cables to the engine, and various parts of the airframe and - terminal and e of that fixes it. I think that should tell me what I need to know, but I've been fooled before, so I'm hoping you guys can lead me down the right path.
    Last edited by flyboyjake; 01-19-2021 at 01:20 AM.

  2. #2
    walt.buskey's Avatar
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    Default Re: Slow starter

    Just pulled my engine; got everything disconnected (I thought), started yanking on it to get it free from the mounts/bushings... and found the ground cable quite by accident. Yep, ripped it right off.

    On my TP, it's a tinned copper braided strap, about 1/2" wide, maybe 4" long, soldered to the upper right engine mount, then bolted to something on the engine (didn't see it, engine's now gone). I now have a new one to solder on....

    Also -- when, right in the middle of a snowstorm, my tractor suddenly refused to start, it was eventually traced to a broken ground strap. Same deal.

    DSC09373.jpg DSC09276.jpg DSC09379.jpg DSC09277.jpg

  3. #3
    Administrator Steve Pierce's Avatar
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    Default Re: Slow starter

    There should be a ground strap like Walt posted. I have made them with standard appropriately sized wire.

  4. #4

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    Default Re: Slow starter

    Quote Originally Posted by walt.buskey View Post
    Just pulled my engine; got everything disconnected (I thought), started yanking on it to get it free from the mounts/bushings... and found the ground cable quite by accident. Yep, ripped it right off.

    On my TP, it's a tinned copper braided strap, about 1/2" wide, maybe 4" long, soldered to the upper right engine mount, then bolted to something on the engine (didn't see it, engine's now gone). I now have a new one to solder on....

    Also -- when, right in the middle of a snowstorm, my tractor suddenly refused to start, it was eventually traced to a broken ground strap. Same deal.

    DSC09373.jpg DSC09276.jpg DSC09379.jpg DSC09277.jpg


    Wow! Thanks Walt! That's very helpful. If I don't have one, would 0 gauge wire be appropriate in size?

  5. #5
    Administrator Steve Pierce's Avatar
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    Default Re: Slow starter

    At least as big as the power wire.

  6. #6
    Glen Geller's Avatar
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    Default Re: Slow starter

    Hi Jake,
    You say you replaced the + cable but was that only the STARTER cable from the starter relay to the starter terminal?
    Do you still have the original aluminum battery to relay box cables, and the cheesy braided straps in battery box, and the external ground?
    They should be replaced with copper cables per SB 836A.
    https://bsd-box.net/~mikeg/N8031W/SB_SL/SB_0836A.pdf
    Note that this also includes replacing the engine-to-ground cable (the strap located on engine mount.)
    Do you still have the cheesy original braided battery positive and ground straps? That's part of the SB too.
    Not difficult to replace those with the same cable used on the starter and properly crimped/staked copper terminals, fresh nuts and washers.

    This is a good time to make sure those battery box pass-thru bolts are well cleaned, the resistance should be only a couple ohms max from battery post to terminations at relay post or fuselage ground.
    I insulted the outside of the positive bolt with a ~4" long scrap of 3/4" dia oil hose, cut a 1" deep notch to clear the pass-thru bolt. Just slip the hose on the cable, connect cable to + bolt, and slide hose-notch back over bolt, and secure it with a monster tywrap if necessary.
    I have dropped items like wrenches and Maglights between the seats and would not like to have them contact the + bolt and seat frame.

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

  7. #7

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    Default Re: Slow starter

    Glen, the plane was restored in 2007, and they changed the 0290-d to the o290d2. All the battery cables were copper, so I'm guessing they were changed then. I put a new one from the battery to the starter relay, then to the starter. There is a copper cable from the battery - to the frame. I looked today and did not see an engine to frame cable anywhere.

    I spin the motor with the mags on for testing again today, and the damn thing spun right up. Then I attached jumper cables to engine boots and the - battery terminal, and it didn't spin any faster. I decided to start it up and run it for a while so compressions would be better for my annual. After i pulled it out, got in and was ready to start, it decided to turn slow again. The only thing that changed was the mixture knob. I'm going to rig up a battery cable to use for engine grounding and see what happens. I'll have replaced everything at that point, i think...

  8. #8
    walt.buskey's Avatar
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    Default Re: Slow starter

    What Steve said. A starter can easily pull hundreds of amps when cranking. Those electrons need a complete path, both to the starter and to ground, in order to function well.

    I found (Amazon, or an auto parts store) a good, heavy, tinned, braided copper grounding strap that I'll use. It's slightly larger than the original, but that's OK. I stayed with the braided strap because I feel they have more flexibility than a stranded cable. Incidentally, that's what my tractor used, which eventually broke the last strand. (If you think our flat fours shake a lot, try a 3-cylinder diesel!) Tinned copper so I can solder it back on, but it could be bolted on. I'm just duplicating the original set-up.

    Also, what Glen said -- I had already done the Bogert battery box mod when I replaced my leaky old Gill with a Hawker/Odyssey gel cell battery. Got rid of the last of the OEM aluminum cables and eliminated two additional electrical connections in the process. Highly recommended.

    Walt

  9. #9
    Administrator Steve Pierce's Avatar
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    Default Re: Slow starter

    You need to I vest in a multimeter.

  10. #10

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    Default Re: Slow starter

    I've got one. I assumed it would show little to no resistance. I figured the resistance would only be an issue with higher amp draw, which of course the multi meter doesn't put out. Am i wrong?
    Last edited by flyboyjake; 01-19-2021 at 11:06 PM.

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