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Roscoe

Starter issue

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The last 3 days, i am experiencing a problem whereby at button push, nothing happens and the starter light illuminates.

 

After a few more attempts, i get a normal start with the light going out as usual.

 

Battery charge is showing 12 Volts at startup. When the starter engages, there is no sluggishness in the start process at all.

 

The Aircraft has had to be moved out onto the grass 3 weeks ago and i am wondering if moisture is the issue as its always early in the morning with high humidity present

 

Today it took about a minute to get started, but when it engaged, it was normal.

 

Would appreciate any assistance guys.

 

 

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Solenoid

 

Jump across the solenoid posts with a car jumper lead.

 

If it turns over normally then it will be either the solenoid itself or the 12v from the starter button to the solenoide. (Or the earth for the actuator coil on the solenoid)

 

 

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Guest Andys@coffs

To be clear, the solenoid has 2 thick red wires, one from battery the other to the starter motor. Frank is suggesting you short across those 2 posts.... Obviously, if the solenoid is the issue, and there has historically been a number of reported failed solenoids on J's, then the starter will engage and the prop will beat the hell out of anyone in its arc.....

 

Andy

 

 

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I had starting troubles and replaced my standard Jab solenoid with a heavy duty one recommended by someone on this forum. When that developed issues my auto electrician informed me the new one was never intended for starting loads; it was designed for caravans etc. He tested the original solenoid and pronounced it in good order. I replaced it and have had no issues since. Just make sure you have a plan B if the solenoid contacts ever weld themselves together.

 

 

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To be clear, the solenoid has 2 thick red wires, one from battery the other to the starter motor. Frank is suggesting you short across those 2 posts.... Obviously, if the solenoid is the issue, and there has historically been a number of reported failed solenoids on J's, then the starter will engage and the prop will beat the hell out of anyone in its arc.....

Andy

Thanks Andy and Frank

 

 

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I had starting troubles and replaced my standard Jab solenoid with a heavy duty one recommended by someone on this forum. When that developed issues my auto electrician informed me the new one was never intended for starting loads; it was designed for caravans etc. He tested the original solenoid and pronounced it in good order. I replaced it and have had no issues since. Just make sure you have a plan B if the solenoid contacts ever weld themselves together.

Thanks for that mate!

 

 

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When you replace the solenoid, it is a good idea to put in a warning light from the starter side of the solenoid. This will only be on when you are pressing the button if all is well. It has been recommended to me that 2 solenoids in series will give protection against a stuck solenoid event, and this is clearly correct but it adds just a bit of weight.

 

The warning light would have helped with the diagnosis of this problem too - it would not have come on when the button was pressed.

 

 

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To be clear, the solenoid has 2 thick red wires, one from battery the other to the starter motor. Frank is suggesting you short across those 2 posts.... Obviously, if the solenoid is the issue, and there has historically been a number of reported failed solenoids on J's, then the starter will engage and the prop will beat the hell out of anyone in its arc.....

Andy

Thats exactly what happened today. Shorted across the Posts and Cranking happened immediately. Ordered new Solonoid.

 

Looks like it can be replaced from within the Engine Bay fairly easily?

 

 

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When you replace the solenoid, it is a good idea to put in a warning light from the starter side of the solenoid. This will only be on when you are pressing the button if all is well. It has been recommended to me that 2 solenoids in series will give protection against a stuck solenoid event, and this is clearly correct but it adds just a bit of weight.The warning light would have helped with the diagnosis of this problem too - it would not have come on when the button was pressed.

Starter solenoids that jam in the open circuit position are an inconvenience but not dangerous. That type of failure is usually caused by mechanical wear in the solenoid coil. Solenoids that jam in the closed circuit position usually do so because high starting current or high resistance at the solenoid contacts cause them to weld themselves together. Two solenoids connected in series doesn't reduce the chance of one of them welding itself closed though it does prevent the starter remaining engaged. Two solenoids simply adds weight and gives you one more point of failure in the electrical system. Fitting an appropriately rated solenoid, preferably one where the contacts wipe rather than just bang together saves weight and complication. A battery master disconnect switch (similar to shown below) if you have room on the panel might be a good option. Get one with a removable key and it serves as a simple anti-theft device as well. The warning light between the solenoid and the starter is a very good idea though. 4650_1.jpg

 

 

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IF the points weld the solenoid (which is connected to the pinion engagement mechanism) holds the pinion constantly engaged and the engine will continue cranking. If it has already started it will destruct the starter drive and/or the starter will also overspeed to destruction. You could end up with a high current electrical path being established in all of this and a FIRE occurring. It is a good idea to have the warning light, to show the current is still flowing.

 

It's also a good idea to have the mechanical isolating current switch above to isolate battery current. It's useful anytime you have smoke you might relate to an electrical fire.

 

If you are unlucky you still have the pinion engagement problem and the damage it might cause as it will do enormous revs with the engine running at any speed above idle. You should hear the odd noise it would cause if you are aware. Nev

 

 

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All correct but on the down side, having one of these isolators accessible would mean heavy cable in and out of cockpit. Your extending unfused cable and they have uninsulated terminals too. Jab very sensitive to voltage drop.

 

Jab bat is on pax side too

 

I have seen cheap versions of these isolators flame out too, key can fall out on some. Some have not so high current rating either.

 

Someone had a cable operated one?

 

 

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To be the most effective and safe they should be located right on the battery, and activated by a mechanical linkage. The battery terminals should be fully covered so no object can contact them ever, and short them out. Nev

 

 

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Terminals in jab battery or solonoid not insulated as far as i know

 

Commoon to see insulation on starter perished

 

Solonoid is right next to bat

 

 

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Short leads are what is needed. Modern cars have quite elaborate insulation on battery terminals and /or around starter terminals, where it is done properly. I would be surprised if they were not to meet a required standard in the country of origin. Nev

 

 

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True JetJr, but flying is a bunch of compromises; risk assessment and risk management. A high current fusible link between the battery and the isolation switch takes care of the un-fused cable problem, but then we have the added complication of two more firewall penetrations unless we go the mechanical linkage route, then there's only one more penetration to worry about. A properly sized mains cable with appropriate gas free terminations should manage the Vd problem, Sturdy heat shrink insulation with good mechanical support and a regular inspection regime helps to keep the crappy insulation rubber from perishing, then we just need an increase in the MTOW allowance to cope with the extra mass. Like I said - compromises.

 

 

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To be the most effective and safe they should be located right on the battery, and activated by a mechanical linkage. The battery terminals should be fully covered so no object can contact them ever, and short them out. Nev

The red plastic key isolator is a great idea, but removing the key is better; if you lightly press it while it's in the "off" position it makes contact.

 

My automatic isolator connects via a wooden rod to the battery's neg terminal, so no long cables are required. As a result of reading on here about solenoid failure I have gotten into the habit, after starting, of isolating the battery for a second or two- if the solenoid terminals had welded themselves together this would allow the bendix to retract.

 

 

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a second master solonoid might reduce failure risk to a low level, would need two solonoids to weld closed at the same time

 

Can anyone reach the firwall from LHS seat?

 

If so these isolators are able to operate with contacts in engine side, key/toggle on other

 

The rubber boot right on the starter cracks and is near impossible to fix, cable goes through right angles in straight boot

 

Would one of these equal a security device?

 

I avoid the MTOW increase by keeping all these ideas in the to do list

 

 

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Does anyone listen to their engine on start up? If you can't hear that the starter is still engaged then I wonder what you are actually listening to. Lights, multiple solenoides, cut out switches etc all will work but same as your car or any other motor - you are still on the ground, not a safety issue, just an overkill.

 

 

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Isolators or whatever you like to call them are just that, an ' isolator ' and not designed to break load current . If used to break the current of a jammed solenoid it may well in fact start a fire . Frank is correct ... Check that the starter has disengaged before moving off .... Bob

 

 

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Isolators or whatever you like to call them are just that, an ' isolator ' and not designed to break load current . If used to break the current of a jammed solenoid it may well in fact start a fire...Bob

How?

 

 

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How?

If the starter solenoid is jammed with the motor drawing full load current, or near to FLC , opening the manual isolator will draw an arc and , if in close proximity to flammable material , will cause a fire ...... Bob

 

 

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If the starter solenoid is jammed with the motor drawing full load current, or near to FLC , opening the manual isolator will draw an arc and , if in close proximity to flammable material , will cause a fire ...... Bob

Sorry Biggles, I have to disagree. Battery isolator switches have been mandatory installations on race & rally cars for yonks. Their primary role is to isolate the battery in an incident and prevent fires. You have the same arcing within the solenoid but it is contained within the body of the solenoid just as the arcing would be contained within the body of the isolating switch. BUT you've gotta spend the dollars and get the right design. Frank (post#20) is right though and any stuck solenoid problem should be apparent immediately on starting and would be a " no go" event.

 

 

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Yeah these isolators range from $5 to $80 for what looks like the same thing

 

Some are " xyz" approved in racing circles

 

Ive seen some cause significant voltage drop, melt, not isolate when operated and just fall to bits and leave pos terminals swinging around. Tough service though

 

And having it isolate itself then the key fall out and get lost spoils your day too.

 

 

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