Burnt starter ground cable

[Lucas]

Hi guys. Yesterday I had an important trip to take unfortunately bird decided to lay low this day. After I turned the key to crank there was only audible "click" and "starter power" on the annunciator panel. After taking the cowling off I've noticed that the ground cable is in pretty bad shape. 

 

[carusoam]

Sure that is a ground cable?

I would expect... ground is through bolting the starter to the engine block....

That might be the live wire going to the starter...

If the insulation has melted off of it... a lot of electricity is going somewhere...

Any idea what melted the insulation off?

Is there a turbo near by?

The melted insulation may have started with a small electrical leak, and got bigger with time...?

PP thoughts only, not a mechanic...

Best regards,

-a-

[Lucas]

This cable is bolted to the firewall burned ground sounds weird and no there is no turbo nearby. I have no idea what happened here. Here is the bigger picture.

 

[carusoam]

Let’s invite @M20Doc to have a look... (M20TN starter with a bare wire...)

Best regards,

-a-

[Guest]

A high resistance from a loose or dirty connection can overheat the cable.  A new cable and careful installation required.

Clarence

[A64Pilot]

6 hours ago, carusoam said:

Sure that is a ground cable?

I would expect... ground is through bolting the starter to the engine block....

That might be the live wire going to the starter...

If the insulation has melted off of it... a lot of electricity is going somewhere...

Any idea what melted the insulation off?

Is there a turbo near by?

The melted insulation may have started with a small electrical leak, and got bigger with time...?

PP thoughts only, not a mechanic...

Best regards,

-a-

Ground is through the engine block, but as the starter is the highest amp load there is, there is logic to ground the block through the starter. Have to connect the ground somewhere, why not there?

Grounds are most often the biggest electrical issue.

‘Funny story, when the Chrysler K car first came out, a great many of them were experiencing CV joint failure, and no cause could be determined, however after a good bit of research a common thing was found with all of them, they were all produced on the same work shift.

‘Chrysler spent millions on warranty work and determining cause of failure.

Anyway the same worker wasn’t torquing the engine ground, so when the engine was started, ground was through the CV joint, this was arcing the balls in the joint which of course caused them to wear fast, and the wear was eradicating the arc spots so cause wasn’t apparent.

So, grounding the starter may be a pretty good thing.

[philiplane]

You'll want to get rid of the teeny tiny Skytec C24-ST3 starter. They are too small for the application, but Continental puts them on anyway because it helps meet the weight limits that aircraft manufacturers want.

 Replace it with the C24-ST5. It will crank much faster.

Then install a new ground strap. 

[Lucas]

Starter died, I've ordered new C24-ST5 and will install it either tomorrow or on Monday. Thanks for your help. 

[StevenL757]

On 4/20/2021 at 6:56 AM, M20Doc said:

A high resistance from a loose or dirty connection can overheat the cable.  A new cable and careful installation required.

Clarence

Exactly this.

[StevenL757]

On 4/20/2021 at 10:17 AM, philiplane said:

You'll want to get rid of the teeny tiny Skytec C24-ST3 starter. They are too small for the application, but Continental puts them on anyway because it helps meet the weight limits that aircraft manufacturers want.

 Replace it with the C24-ST5. It will crank much faster.

Then install a new ground strap. 

Why wouldn't he want the Energizer starters that are known to be more reliable?  Won't he be potentially shredding starter adaptors with the Sky-Tec products on engines as large as the TSIO550?

[Guest]

You can spend your money on an Energizer starter or a Tempest starter now and hopefully not spend it on an adapter and one of these starters.

Clarence

[philiplane]

4 hours ago, StevenL757 said:

Why wouldn't he want the Energizer starters that are known to be more reliable?  Won't he be potentially shredding starter adaptors with the Sky-Tec products on engines as large as the TSIO550?

Shredding comes from starters that don't release quickly and completely. Take your pick of Energizer or Skytec C24ST5. Both crank well, both release well. The Skytec is many pound lighter, which is critical on an already nose heavy Mooney.

[carusoam]

Which Skytecs were used in some long bodies?

Sounds like there may have been more than one to select from...

One was underpowered and didn’t work very well... but, that was a couple of years ago...

I have the energizer... and would love a few pounds off the nose... (when the time comes)

PP thoughts only,

-a-

[skykrawler]

On 4/20/2021 at 3:18 AM, carusoam said:

Sure that is a ground cable?

I would expect... ground is through bolting the starter to the engine block....

...snip...

PP thoughts only, not a mechanic...

Best regards,

-a-

@carusoamThe motor is insulated from aircraft ground by the isolators.  So... a ground strap from the motor to the aircraft frame is required for the starter to operate as well as any sensors that provide resistance to ground attached to the engine like oil temp.

[Lucas]

Replaced starter, works like a charm 

[bfreelove]

On 4/23/2021 at 9:45 PM, carusoam said:

I have the energizer... and would love a few pounds off the nose... (when the time comes)

PP thoughts only,

-a-

I would recommend the Hartzell Engine Tech PM2407.  It’s almost 4 lbs lighter than the Energizer so in between that and the Sky Tec.  It’s a permanent magnet design and cranks faster than the other two.  At $1150 it’s a bit spendy, but for me it was worth it for the better cranking and piece of mind in regards to the starter adapter and less worry about kick backs.