Starter dead - Anything left to check?

[morleyz]

Went out to take a spin in my '72 Piper Arrow II. Pre-flight, roll it out onto the apron, go to start and nothing. Not even a prop wiggle. Threw the jump starter on it to see if maybe I had a bad battery, nothing. Pushed her back into the hangar and did some troubleshooting.

- Starting circuit breaker not popped
- Removed cowl and in the hangar I can clearly hear the solenoid clicking. Voltage at the ship side of the solenoid is 13.8. When "cranking", it drops under 13V measured at the starter side of the solenoid.
- No whirring sound from the starter (I read this is what you would hear in a bendix failure)
- I marked the starter gear with a red sharpie. Doesn't seem to be turning (or I miraculously got it to stop every single time in the exact same spot)
- I can easily turn the shaft by hand
- When cranking, lights dim, etc. so something is drawing a good load
- Just for grins, it was suggested in the service manual to jumper the solenoid, so I did try this with some #4 battery cable, still not a click or a wiggle from the starter

Never had a slow start or a failed start before and I was out about 8 days ago without issue.

Is there anything else I should check before declaring the starter dead? If it is dead, despite the ridiculous cost, I will go with an upgraded Skytec unit vs. direct OEM replacement/rebuild of my unit, but figured I'd save me some $$ on the labor if I scheduled an A&P for a replacement and had the unit ready rather than a diagnostic.

 

[bbchien]

if it's "click-click'-click" you might have 13V static, but you don't have any amperage to support it, and it drops instantaneouly upon engagement. The fact thatn you're not gettin 13.2 V on static test might also be significant.
I'd borrow a know good battery and try that first.

If it cranks then you know you have a sulfated battery.
If it doesn't I'd still change the ground strap it it's never been changed and clean teh contact between strap and ground. That thing is 41 years old and there are SIGNIFICANT losses through there. Enough so that on my Seneca, when we'd load up the electrics, the panel voltage would drop enough to reset my 430W.

BTDT.

 

[Dan Thomas]

If it drops from 13.8 to 13.0, the starter is defective or you have a bad engine-to-airframe ground strap. That voltage should drop considerably more than that under a full draw. The starter should spin even at 13 volts.

There are four brushes in the old series-wound starters. If one brush is worn out or sticking, half of the starter is dead.

The cable between the starter and solenoid needs checking, too. Put the voltmeter right on the starter terminal and see if you get 13V there. If it's lower than at the solenoid, the cable is probably corroded between the copper wire and the crimp terminal. It will get a bit hot when you're trying to crank.

 

[Magman]

If you can find jumper cables long enough you can “ build” the circuit

directly to the Starter and back to ground as well.

 

[Dan Thomas]

I made a couple of long jumpers for just that.

One has to check the voltage between the starter's terminal and the starter case. That rules out the engine's ground strap and get the real story. If he gets 13 Volts that way, and the starter doesn't fire, the starter is pooched. He should tap it with a hammer near its aft end and see if it cranks. Sticking brush, if that works. It needs rebuilding or replacing.

Piper doesn't mention the starter brush check in their service manuals' inspection checklists. Probably wouldn't make much difference anyway. Most mechanics don't follow those lists.

Cessna does, though. This from the R182 manual:



That letter J means this:



Every 100 hours those brushes should get checked. That would avoid stories like the OP's, probably. Now, at overhaul, is that starter being overhauled too, or is the mechanic just taking it off the old engine and installing it on the new?

Note also the 500-hour alternator brush inspection. Another one that gets ignored, and we see plenty of alternator failure stories here.

 

[Lance F]

Solo student reported our training 172 wouldn't start on Monday. Found this after pulling starter. Got overhauled starter and was quickly flying again. Fortunately no damage to ring gear on flywheel. Don't know what happened. I hope the OP has a simpler and less expensive problem.

 

[Domenick]

The starter pinion gear experienced a RUD.
Much preferable outcome than a damaged ring gear.
I know Piper's OEM starters have replaceable bendix drives. Not sure About Cessna.

 

[morleyz]

Thanks for all the advice. A&P and I have agreed that the pretty old Prestolite starter is toast. Ordered a Sky-tec and we'll install next week. Turns out the weather would have cancelled my Thanksgiving trip anyway, so no real loss besides a few $$ for the upgrade.