Skytec Starter issues? Sort of intermittant...at a loss for how to troubleshoot

[torrensc]

We have the following issue. Would appreciate any guidance from anyone more knowledgeable than ourselves (and it doesn't take much!)

1965 M20E, Skytec 12V PM starter

We'd been having problems with slow prop rotation, delayed prop rotation during start....so, 4 months ago -- bought a new battery

Then one day, prop wouldn't turn at all.  Mx person came out and tapped on the starter with a hammer and a piece of wood, aircraft then started...and continued to start perfectly for the next 12 flights...but as a precautionary (after talking to Skytec), we replaced the Skytec starter last month (PM 12V model)

Everything works fine for another 20 starts. THEN...Yesterday...same thing, prop won't turn during start

Yesterday:

• Tried hooking up external power and even at 13.4 volts, prop won't spin during start.  Can hear the shower of sparks, but prop won't spin.
• Tried tapping on the starter, still won't start. Gave up.

Today:

• 11.8 volts on the battery (no external power)
• Master Switch on -- can hear and feel the Master Relay switching (located on side of battery container), plus we get all the power inside.
• Ignition Switch on START-- can hear and feel the Master Relay for the starter switching positions (located on the firewall).  
• Can hear the shower of sparks, but prop won't spin.
• Tried Tapping on the starter several times. Retry the start several times, prop won't start.
• Hooked up external power, 13.4 volts, this time the thing starts!  And it starts up 4 or 5 more times (w/o external power), no problem.

Anyone have any ideas?  We don't want to get stuck somewhere! Is it the tapping on this NEW starter that is fixing it?  Should we ask Skytec to send us yet another starter? Is there anything else it could be? Anything else we should do?

Thank you in advance!

 

[DVA]

Have you checked the starter solenoid as a possibility of the intermittency?

[Hank]

What's causing your battery voltage to drop? 11.8 V isn't normal or good.

[DonMuncy]

I had a starter on a Continental which was intermittent. Whacking it would usually make it go. Eventually found a bad solder joint between the big post on the starter at its connection inside the starter.

[ArtVandelay]

Check the voltage at the battery and at the starter, it should be about the same, if not, you have a bad connection somewhere. Check the battery side of the solenoid, the solenoid could be closing but not making good contact.

[Drew_Wagner]

Check your master relay. Run a voltage test on both sides and if there is a large drop you have found your culprit. Exact same symptoms I had. I agree that 11.8V you have resistance somewhere!


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[Guest]

Here is the Skytec troubleshooting flow chart.

http://www.skytecair.com/Troubleshooting.htm

Clarence

[Yetti]

All terminals should be shiny.   Could be a solenoid or half a leg of your armature not happy

[Piloto]

Check the engine ground strap connection to the firewall. Clean it and secure it.

José

[torrensc]

Hello Everyone thank you.

I have a 12 Volt battery.  The 11.8 V is what I read off the digital ammeter in the cockpit...you guys say this is low...what should it read before start? Skytec says the starter should turn at anything above 10V...?

We have tested both the master solenoid (located next to the battery) and the starter solenoid (located on the firewall) to the extent that we can hear them click and you can feel the click (when you put your hand on it and the switch in the cockpit is moved).  Plus, the skytec starter is brand new (30 days), so you'd think it wouldn't be something internal to the starter AND this was the exact same problem we had before we got the replacement starter (so I'm guessing I replaced the starter for no good reason -- since the problem is still here).

Next time the problem surfaces, we will go systematically through the Skytec troubleshooting guide (unfortunately  can only do this when the intermittent failure presents itself).

And finally, what is this: " half a leg of your armature not happy"   armature? where is that? how do I check that?

We will check all connections and the ground strap!  Thank you all!

[cnoe]

Use a DMM (digital multi-meter - available at Sears for $20) set on ~24V DC to check the voltage from your starter solenoid to a nearby ground. It should read ~12V+ while cranking. If it doesn't you've likely got a bad solenoid or bad connection elsewhere. If it reads 12V+ and still no worky then suspect the engine ground or starter itself.


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[1964-M20E]

I would before replacing any more parts go and clean all the connections on the big cables from the battery up to the starter including all grounds.

Intermittent gremlins are hard to find but the process of elimination works every time.  Double check the cables as they come from the battery to the engine compartment and make sure there are not partial shorts existing.  This happened to me on a car once and drove me crazy until I found the offending battery cable.

 

 

[Andy95W]

How old does your starter solenoid look?  I have seen similar symptoms with very old components that you will not be able to  see.  Over the years, carbon builds up on the contacts inside the solenoid and the electromagnet no longer pushes with sufficient force to make a good connection across the contactor.  And this can be cold weather related- as it gets colder there is greater friction inside the solenoid which makes the intermittent problem occur more frequently.

https://www.aircraftspruce.com/pages/el/relays/sts-12s24s.php

Only $69 and it's even PMA'ed for every Mooney from C through S.

When you replace it, it will also be a good time to clean all the heavy gauge cable connections.

I also like Piloto's idea of ensuring your main engine ground strap is still in good shape.

[DonMuncy]

4 hours ago, torrensc said:

 

I have a 12 Volt battery.  The 11.8 V is what I read off the digital ammeter in the cockpit...you guys say this is low.

 

I, too, had a low reading. I didn't know it was a problem until someone flying with me mentioned it. Eventually turned out to be a bad voltage regulator.

[RobertGary1]

Been there too. Sometimes I'd try multiple times to start it. Almost got stuck in Mexico.  Sent it to Skytech. They found an issue and went ahead and did a full rebuild for $200.

 

-Robert