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Is this a normal start?


DingyHarry

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When I crank the motor, the prop barely turns over once reaching compression. I had the shop test the battery and they say its fine. The engine still fires up within a few seconds but prior to the start, its as if the starter can barely turn over the motor. Guages show 13.5 volts when started so i don’t think its the alternator.  Do I have a bad starter? Is this normal? Thanks for the help. 

Edited by DingyHarry
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My C does the same thing. Battery tests okay. We once found a loose connection on the start solenoid and I figured I had found the culprit, but it still is a slow starter. Statts every time though... interested to hear other ideas.

Edited by Johnnybgoode
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25 minutes ago, DingyHarry said:

When I crank the motor, the prop barely turns over once reaching compression. I had the shop test the battery and they say its fine. The engine still fires up within a few seconds but prior to the start, its as if the starter can barely turn over the motor. Guages show 13.5 volts when started so i don’t think its the alternator.  Do I have a bad starter? Is this normal? Thanks for the help. 

Generally, it would be helpful to know what kind of plane and motor you have, but...

No, that is not normal for any motor.  The fact that it fires up only tells you the ignition, fuel and air systems are working okay, but doesn't say anything about the starter.  getting it fixed is a pretty high priority, lest you be tempted to become like that cirrus pilot who tried hand-propping his plane... :blink:

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Not normal.  Could be the starter.  Could be worn or high resistance contacts in the starter solenoid.  Could be a loose are dirty connection. Not the alternator although the charging voltage is a bit low (albeit normal for an Interav conversion alternator).  How old is that battery? Battery voltage at rest is not an accurate gauge as whether the battery is good.  

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35 minutes ago, DingyHarry said:

When I crank the motor, the prop barely turns over once reaching compression. I had the shop test the battery and they say its fine. The engine still fires up within a few seconds but prior to the start, its as if the starter can barely turn over the motor. Guages show 13.5 volts when started so i don’t think its the alternator.  Do I have a bad starter? Is this normal? Thanks for the help. 

Nope.

Type of starter?

Voltage at starter relay?

Could be bad ground.

I had a Skytec that operated that way for two years with a broken shear pin. It was the damnedest thing. 

 

Edited by Shadrach
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That's what mine did before giving up the ghost.  I didn't know it wasn't supposed to be so slow because it always started in just a few blades.  Eventually, it wouldn't overcome the compression stroke and was replaced.  Now I can almost taxi with the starter.

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Concorde (the battery manufacturer) would say that 13.5 volts is too low.  Their Manuals say it should be around 14.0-14.2.

I've seen bad relays "rob" voltage from the starter (where it's most noticeable).  Usually it's the starter relay, once it was actually the master switch relay.  The contacts get old and burned and the carbon cuts current flow.

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I’ve gone through a slew of starter issues on an o-360 equipped Cherokee 180. I would have to bump the starter multiple times to get through each compression stroke. A skytec starter helped, switching from Gill to Concorde RG helped more, and switching from aluminum starter cables to copper while also cleaning all contacts helped the most. 

Edited by 81X
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11 hours ago, DingyHarry said:

When I crank the motor, the prop barely turns over once reaching compression. I had the shop test the battery and they say its fine. The engine still fires up within a few seconds but prior to the start, its as if the starter can barely turn over the motor. Guages show 13.5 volts when started so i don’t think its the alternator.  Do I have a bad starter? Is this normal? Thanks for the help. 

Here is the troubleshooting guide from SkyTec, it’s applicable to any starting system though.

https://skytec.aero/aircraft-starter-performance-issues/

Clarence

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My e-model does that.  When I try to start, the first time it hits compression, it will stall and/or pull through slowly.  Once it's through that first compression it turns over with no issues.  I usually come off and try again and it will make it through that first compression easily the second try.  Mine is fuel injected and I had heard at one point that it is a symptom of the SOS system so I have never worried about it.

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Check and clean every connection from the battery to the starter and back including the grounding connections.

Then check the resistance across the master relay and the starter solenoid these should be zero ohms.

You will need to disconnect the outgoing power cable from the master relay  and starter relay while doing this so the starter does not try to engage even then remain clear of the prop while doing this.  You will need to turn the master on and measure resistance across the master relay and then have someone engage the starter relay while measuring resistance across the starter solenoid.

What starter is on the plane and how old is it?

 

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11 hours ago, Andy95W said:

Concorde (the battery manufacturer) would say that 13.5 volts is too low.  Their Manuals say it should be around 14.0-14.2.

I've seen bad relays "rob" voltage from the starter (where it's most noticeable).  Usually it's the starter relay, once it was actually the master switch relay.  The contacts get old and burned and the carbon cuts current flow.

Sky-tec (Hartzell) told me that the the 149-NL should have adequate to crank with 10V or more at the starter solenoid.  I found that to be wishful thinking.  After testing, I noted less than a 1V drop from bus to solenoid.  I see a severe drop in performance when bus voltage drops below 12V.  Fortunately my little Keyline desulfator/tender keeps my Concorde  at a healthy 12.4V (at the bus).    

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