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Almost AOG - starter wouldn't crank

wjb

Well Known Member
Hi All,

I was able to help an almost AOG -14 today get the fan started after what looked initially like a soft battery. After trying to give it charge, the battery looked fine; wouldn't pull any significant charge current.

Symptoms were that the starter solenoid would click, but we would get no other sound or prop motion. The bus voltage didn't drop when the starter was engaged. Seemed like a starter wiring connection was bad.

However, I did notice that the prop had stopped straight up and down from the previous shutdown.. this seems quite rare; not sure if I've ever seen it stop that way myself.

So, before considering pulling the cowl to investigate, I pulled the prop through for a revolution ... and then we tried starting et voila, she came to life, no issues. A very solid crank and a start.

I'm not sure what the root cause would be here .. anyone care to opine?
 
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Been there -- Done that...

Sticky starter solenoid (not the starter relay). Usually seen when engine is hot. Others have seen a cold/cracked solder pool on this unit as well. Net effect -- it won't fully extend, so it won't complete the circuit to the starter motor.
 

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Two other items to check:

- all starter wiring connections
- ground straps

The starter current path to ground goes through the engine / engine mount. Many builders have added an extra grounding strap or cable from engine directly to firewall (in my case to the same point where battery ground attaches). I ran a heavy cable from the same point where the engine ground strap attaches to the engine mount to the firewall.

If any of the wiring is loose or has high resistance could cause intermittent starter issues.
 
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If you have a Skytec 149LS starter it is most likely the solenoid on the starter as bjdecker mentioned. Replacement is a common auto store part. Added** Borg Warner S5613 is the part number
 
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I had similar intermittent symptoms on a skytec starter with not many hours.

It turned out to be the starter integral solenoid that engages the gear and switches the current to the starter motor. A quick fix when you get the replacement. One from a 2005 Ford Crown Victoria works perfectly!
 
Prop position

Different prop manufactures have different prop 'clocking' apparently, but my Whirl Wind 200RV prop normally stops horizontal, which is exactly between compression strokes. I guess that means all the pistons are in the middle of their stroke, either up or down.

Every once in a while, it stops vertically, which is at TDC for one of the cylinders. I think this tends to happen if I pull the mixture with the engine turning higher RPM. The greater prop inertia seems to be able to carry the prop up just one more compression stroke as it coasts to a stop.

I haven't noticed whether the starter seems to have a bit harder time getting going in those cases.
 
I had similar issue on 1 1/2 year old RV10. THe issue happened several times, I tracked the root cause down to the starter relay (standard relay supplied included in Kits - ES-24021)

I broke open the old relay and found a lot of corrosion inside. Not sure how this happened, airplane is hangared. I replaced the relay and bought a spare for the next time...


While troubleshooting the issue, I was getting very weird resistance readings across the main contacts on the relay, the corrosion chemistry was creating ghost voltages with the part fully disconnected)

Due to these ghost voltages and funky resistance readings internal to the realy, it took me a while to figure out I had a faulty starter relay.

Steve
 
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