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Burnt new starter

Ron B.

Well Known Member
First off I'm not blaming anyone . Do not know the cause. Only looking for the cure as it has all parties stumped so I'm looking for ideas here.
Helping build a friends RV-14 with the EXP 119 engine. I know most will say a wiring issue , have at it but I have had enough people go through the wiring that I am personally ruling that one out unless people can tell me that Van's instructions will cause this scenario (don't think so).
Other than two thing which I will document , everything is connected as per Van's instructions.
(1) the #8 wire WH-P912 wire leaves the battery side of the starter relay (on the firewall) then goes up to the two shunts (jumped) then through the firewall to the main buss. The WH-P909 leaves the main alternator and goes to the shunt mentioned above as does the power from the standby alternator (second shunt) .
(2) Builder elected to install a 60 amp. switch mode power supply and it connects to the main buss via a CB. With the master off and you switch the power supply on , it powers up the avionics for ground testing and training. With the power supply on , 12V. can back track all the was forward to the battery side of the start relay (on the fuselage) then across the copper bar joining the start relay to the ship side of the master solenoid (but with the master off (as would be the case if your using the power supply) the power is not connecting to the battery). In case you have a battery charger on the battery and you want to play with the avionics.

Now as to what happened. On the initial panel power up with the ground power supply and no key in the ignition, we heard a click. It was the starter drive jumping forward. No turning just jumping forward every time power was applied (and clicking each time) . When power was removed the drive would back out. The start relay was not clicking. When you turn the key the start relay( on the firewall) has a loud click as it should. We tried to trouble shoot for quite a bit and all of a sudden it(the starter drive) stopped clicking and pushing the drive out. Strange it would stop after doing this many times. Jump forward a few days and we do the first engine start up and everything is working as it should. The next day (yesterday) we have the power supply on testing a few more things. Noise in the hangar ( I guess) as we did not hear the drive engage this time only to smell smoke. Smoke was coming out of the started. It was removed and sent to a engine builder and they disassembled it and as we expected it toasted the start solenoid on the starter.
With the starter removed , I cannot duplicate any scenario that applies power to the starter wires. We have been in contact with Van's , Lycoming and Hartzell . Other than you must have wires mixed up no one can explain our mystery. As Hartzell (Skytec) explained and I agree if the start relay wasn't forwarding power to the starter there wouldn't be power there to burn the starter up so it cannot be the starter's fault. The start relay had to be providing power some how or this would not have occurred. If the start relay was providing full power the starter would have turned.
Finally my question, can a faulty start relay (as mounted on the firewall) fail and pass power from the battery side without being commanded? I know they can stick on. Regardless , it's coming out and being replaced but it would be nice to know what took place. If the problem isn't the relay and it doesn't act up right away, I would hate to have this happen again let alone while in the air.
Thanks for reading such a long post, Ron
 
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You may need to draw up a wiring diagram to get some help...........

I can't visualize what's going on with just words (some people probably can, others can't).
 
Do you have the ‘I’ terminal from the contactor going to the starter solenoid?
If yes I would disconnect it and put the jumper back on the starter.
 
On the initial panel power up with the ground power supply and no key in the ignition, we heard a click. It was the starter drive jumping forward.


Sounds like you're lucky it didn't turn the engine over. This is why I tell new passengers the prop is "the end that bites", and always make sure to announce when the power is going on and ensure nobody is near the prop arc.

Good luck, and let us know what you find out, please.
 
I confess to looking for a zebra in a horse corral here, (meaning, a wild obscure idea where there is probably a simpler explanation) :

but is there any chance that the ground path (meaning the engine case) could become energized with a return path to ground through a cable, that had low, but non-zero current capability? Enough to activate the solenoid but not enough to turn the motor?

Just as an example of the type of situation I'm talking about, is hooking up trailer lights to a car. You turn on a turn signal, and you notice that not only is the turn signal light on the trailer blinking, but so is the brake light. What is happening here is that in the presence of a weak ground, the current from the turn signal is finding a way back to ground through the brake light bulb.
 
I think Walt is on the right track, the solenoid is being energized without power to the starter motor. That solenoid is not a continuous duty coil, so after a period of time, it will burn up.....
 
On the (defective) firewall start solenoid check continuity from the I terminal to the battery stud. If there is continuity, it's defective, and that would send power to the starter-mounted solenoid without powering the motor.

And, if the master solenoid is turned on via Master switch (with main battery installed), that should have also energized the starter-mounted solenoid (with the "defective" firewall start solenoid still installed).

That would also mean the starter pinion gear would have been engaged into the ring gear the entire time the engine was running. You can't hear if that was the case; I've seen two instances where the starter solenoid was engaged continuously until the motor burned up and neither time could the pilot tell this was happening.

What Walt said about removing the wire to the I terminal and reinstalling the jumper at the starter would have fixed this too.

Also, FWIW, the solenoid on the starter is cheap enough and easily replaced. 2000 Ford Crown Victoria is one of the original applications.


EDIT: if the battery and starter (bus bar and WH-P16) wires were reversed on the firewall start solenoid, this would have also caused your problem. Installing the solenoid upside down would have led to this.

solenoid.JPG
 
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On the (defective) firewall start solenoid check continuity from the I terminal to the battery stud. If there is continuity, it's defective, and that would send power to the starter-mounted solenoid without powering the motor.

And, if the master solenoid is turned on via Master switch (with main battery installed), that should have also energized the starter-mounted solenoid (with the "defective" firewall start solenoid still installed).

That would also mean the starter pinion gear would have been engaged into the ring gear the entire time the engine was running. You can't hear if that was the case; I've seen two instances where the starter solenoid was engaged continuously until the motor burned up and neither time could the pilot tell this was happening.

What Walt said about removing the wire to the I terminal and reinstalling the jumper at the starter would have fixed this too.

Also, FWIW, the solenoid on the starter is cheap enough and easily replaced. 2000 Ford Crown Victoria is one of the original applications.


EDIT: if the battery and starter (bus bar and WH-P16) wires were reversed on the firewall start solenoid, this would have also caused your problem. Installing the solenoid upside down would have led to this.

View attachment 17885

If the starter relay was mounted upside down the copper bar would not fit. It's not upside down unfortunately (looking for a cure) but thanks. I will check the "I" terminal to the battery stud but my problem is it's obviously intermittent.
 
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Do you have the ‘I’ terminal from the contactor going to the starter solenoid?
If yes I would disconnect it and put the jumper back on the starter.

Yes Walt, I do have the jumper removed and "I " going to the start solenoid as per Van's instructions. Thanks
 
I confess to looking for a zebra in a horse corral here, (meaning, a wild obscure idea where there is probably a simpler explanation) :

but is there any chance that the ground path (meaning the engine case) could become energized with a return path to ground through a cable, that had low, but non-zero current capability? Enough to activate the solenoid but not enough to turn the motor?

Just as an example of the type of situation I'm talking about, is hooking up trailer lights to a car. You turn on a turn signal, and you notice that not only is the turn signal light on the trailer blinking, but so is the brake light. What is happening here is that in the presence of a weak ground, the current from the turn signal is finding a way back to ground through the brake light bulb.

I will look to see if I can find stray current, Thanks
 
On the (defective) firewall start solenoid check continuity from the I terminal to the battery stud. If there is continuity, it's defective, and that would send power to the starter-mounted solenoid without powering the motor.

And, if the master solenoid is turned on via Master switch (with main battery installed), that should have also energized the starter-mounted solenoid (with the "defective" firewall start solenoid still installed).

That would also mean the starter pinion gear would have been engaged into the ring gear the entire time the engine was running. You can't hear if that was the case; I've seen two instances where the starter solenoid was engaged continuously until the motor burned up and neither time could the pilot tell this was happening.

What Walt said about removing the wire to the I terminal and reinstalling the jumper at the starter would have fixed this too.

Also, FWIW, the solenoid on the starter is cheap enough and easily replaced. 2000 Ford Crown Victoria is one of the original applications.


EDIT: if the battery and starter (bus bar and WH-P16) wires were reversed on the firewall start solenoid, this would have also caused your problem. Installing the solenoid upside down would have led to this.

View attachment 17885
If the starter solenoid on the starter was activated when we ran the engine it would have burned up then as we ran it per the Lycoming start process and ran it at 1500 rpm for 15 minutes. When it burnt we only had it on for two or three minutes (guess), but certainly not close to 15.
Thanks
 
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