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  #1  
Old 06-25-2018, 11:31 AM
Dale D's Avatar
Dale D Dale D is offline
 
Join Date: Aug 2017
Location: Zeeland, MI
Posts: 12
Question Cranky Starter II - (No Swingy, No Starty)

Hello. I have read as many “cranky starter” and “starter problem” threads as I can find, but I am running out of ideas to solve my starter problems on my Lycoming IO-320 standard compression engine. I have a Hartzell 2-blade C/S metal prop with 1 Slick Mag & 1 Lightspeed CDI ignition module. Total time on engine is 300 hrs, and I use Phillips 20w50 X/C oil.

My Symptoms:
My key ignition switch takes 3-4 attempts to get the prop to move past the compression stroke before it will swing the prop to start. (The engine starts up just fine, once the prop is swinging.)

My Actions & Results To-Date:
Replaced 7 yr-old 12V Odyssey PC680 battery with new Odyssey PC680 battery 4-mos. ago.
Result: Same start-up symptoms with my existing permanent magnet Sky-Tec 149-LS Lightweight starter.

Cleaned all cable and wire connections from battery to starter - positive and negative.
Result: Same start-up symptoms.

Replaced starter with new series-wound Sky-Tec 149-NL starter 3 weeks ago.
Result: Same symptoms with new starter.

Replaced Starter Contactor with new Starter Contactor 2 weeks ago.
Result: Same start-up symptoms.

Replaced Master Contactor with new Vans Master Contactor this past weekend.
Result: Same start-up symptoms.
Note: Output lug of master contactor is joined to input lug of starter contactor with 3-1/4" length, double-thickness of copper bus bar.

Measured Voltage at various locations, per Sky-Tec’s trouble-shooting guide: 13.0 Volts (No-Load) at battery, 11.0 Volts (When Prop is Cranking) at battery, 10.6-10.7 Volts at starter (When Prop is Cranking), No measurable resistance on major power and ground cables. Above Voltage tests were with newest Odyssey battery, alone.

Hooked old & new Odyssey batteries in parallel and retested.
Result: Same start-up symptoms.
(Once the prop did start swinging, it did swing with more authority.)

Talked to Alan at Sky-Tec support this morning. He is perplexed, too, as 10+ Volts at the starter should provide plenty of torque to start without stalling. However, he requested I make the following additional test:

“Disconnect the starter contactor’s positive cable from the new starter, and hook up a 12V starter caddy or known good 12V battery directly to the starter’s positive lug and good ground to eliminate potential upstream problems.”

The above test sounds simple enough. But frankly, the idea of making contact with a cable end that will have 100-200 Amps flowing through it scares me to death! I imagine some arcing sparks would occur, too.

Can someone suggest a safe way to complete this test?
Do you have any other suggestions that I may be missing?

I have nearly run out of parts to replace.

Thanks,
Dale
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  #2  
Old 06-25-2018, 11:57 AM
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maniago maniago is offline
 
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Default

What about with the igniton off? How well does it swing then?

How about with the plugs removed?

Does your ground cable connect to the engine case, or does it run right up to the starter and bolt to its case?
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  #3  
Old 06-25-2018, 12:07 PM
170 driver 170 driver is offline
 
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Try adding a heavy ground strap between the engine block and the firewall or the negative battery post. Had the same happen to me on a cessna one time, bad ground to engine. I tried doing it with jumper cables just to test the theory, it didn't work, had to put on a strap.
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  #4  
Old 06-25-2018, 12:19 PM
KAdriver KAdriver is offline
 
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Location: Louisiana
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Have you checked the key switch? Had similar problem. Discovered as long as I didn’t turn the key to the stop it started every time.
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  #5  
Old 06-25-2018, 12:32 PM
lr172 lr172 is offline
 
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Check your ground cable/strap from battery or ground block to the engine block. the continuity/resistance of this is just as important as the positive side. Your symptoms are typical of low current, which can often be traced to high resistance somewhere in the circuit, assuming the battery is sound. The initial crank take quite a bit more energy than once its spinning.

Larry
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Last edited by lr172 : 06-25-2018 at 12:34 PM.
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  #6  
Old 06-25-2018, 12:43 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by lr172 View Post
Check your ground cable/strap from battery or ground block to the engine block. the continuity/resistance of this is just as important as the positive side. Your symptoms are typical of low current, which can often be traced to high resistance somewhere in the circuit, assuming the battery is sound. The initial crank take quite a bit more energy than once its spinning.

Larry
I agree

Or even more basic.

Verify that the airplane even has one. This is a commonly missed detail.
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  #7  
Old 06-25-2018, 01:48 PM
BillL BillL is offline
 
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Location: Central IL
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Default Ground your voltmeter to the starter if you didn't already.

Easier than checking the physical grounds is when measuring voltage to the starter it should be in reference to the ground of the starter housing, or the voltage across the starter.

I ran a separate wire w/ground for this purpose in my trouble shooting. Safe
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  #8  
Old 06-25-2018, 01:48 PM
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airguy airguy is offline
 
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Quote:
Originally Posted by lr172 View Post
Check your ground cable/strap from battery or ground block to the engine block. the continuity/resistance of this is just as important as the positive side. Your symptoms are typical of low current, which can often be traced to high resistance somewhere in the circuit, assuming the battery is sound. The initial crank take quite a bit more energy than once its spinning.

Larry
Yep - just because you've got 10.6 volts on the positive side of the starter won't help you a bit if you've also got 3 volts on the negative side of the starter due to a poor ground.
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  #9  
Old 06-25-2018, 02:33 PM
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Dale D Dale D is offline
 
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Default Ground Straps & Key Switch

Quote:
Originally Posted by lr172 View Post
Check your ground cable/strap from battery or ground block to the engine block...
Larry
Larry & Others,
I have two ground cables. One approx. 8" mesh ground strap originates from the battery's negative post and terminates to the firewall. The 2nd approx. 18" #2 ground cable originates from the engine block to a 2nd location on the firewall.
I have measured "0" ohms resistance between: battery negative post & ground cable #1 end, battery post & ground cable #2 at firewall, and battery post and starter housing.
However, I can try running a substantial cable directly from the starter case to the negative battery post.

Maniago,
I'm not sure how I would disable the ignition, short of removing all plug boots, as the ignition is part of the key-switch.

KAdriver
You raise an interesting possibility with the key-switch that I haven't yet explored. I have never really paid attention to where my key position is when the prop stops. This will be an easy one to check this evening.

Dale
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  #10  
Old 06-25-2018, 02:52 PM
lr172 lr172 is offline
 
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Quote:
Originally Posted by Dale D View Post
Larry & Others,
I have two ground cables. One approx. 8" mesh ground strap originates from the battery's negative post and terminates to the firewall. The 2nd approx. 18" #2 ground cable originates from the engine block to a 2nd location on the firewall.
I have measured "0" ohms resistance between: battery negative post & ground cable #1 end, battery post & ground cable #2 at firewall, and battery post and starter housing.
However, I can try running a substantial cable directly from the starter case to the negative battery post.
Dale
Do you know if the 8" mesh strap is a #2 or #4 gauge? If the plane has several years on it, it may be worth pulling both straps and make sure the connections don't have corrossion. It is possible to have 0 ohms, but not enough surface contact to support 300 amps.

I would also test voltage drop on the starter. Place one probe on 12v terminal on starter and the other on ground then crank and observe reading. Give the results to skytech. With everything you have done, I also would be at a loss. You either have a source/transport issue that is limiting current or your starter is unable to convert that power to rotation. Your ignition switch is not an issue. Either the contactor closes or it doesn't. Pretty binary. Actually, I take that back. The starter contactor draws 4-5 amps on the coil. If you had a significant resistance in the switch, it is possible that it can't pass enough current to fully close the contactor. However, this would likely result in occassional chatter of the contactor.

Larry
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Last edited by lr172 : 06-25-2018 at 03:07 PM.
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