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JimRice 10-13-2017 10:04 AM

Bendix Kicking Out after 2 Blades
I recently began experiencing an issue with my starter on my O-320D1A on my RV-4. It is a regular Prestolite (IIRC) starter (not Sky-Tec or other lightweight starter).

It always seems to crank fine cold on first start of the day, but on subsequent starts, the prop will only turn two blades and the Bendix will kickout/disengage. I let it spin down, try again with same results. My battery (Power Sonic) is less than 2 years old and stays on a Battery Tender when in the hangar.

I'm going to dig into this this weekend but wanted to inquire here first for some ideas where to check first.

Since it always starts well after coming off the battery charger without kicking out, I'm leaning towards this being a battery, relay or grounding issue. I don't think it is a problem with the starter or ring gear, but will definitely be looking at them too.

I am thinking there is sufficient voltage for first start due to battery being topped off by Battery Tender, but it loses charge after sitting even a couple of hours without being charged. When it first happened, once I got it started and flew home, once I landed I shut it down and immediately tried starting and it started just fine. Three times. At that point I thought I might be having a switch issue (Typical keyed switch with starter position). The next time, I went to fly, it started well for first flight, but after sitting at a buddy's strip for 2-3 hours, it did the 2 blades and kicked out again. Once again, I was able to finally get it started, trying two blades at a time and flew home. Once again, when I got home, it started just fine.

My plan tomorrow is to open it up and begin inspecting/troubleshooting. I think first thing will be checking voltage drop at the starter...I may go out and take the charger off overnight so it won't be freshly charged. If it isn't the battery, I suspect the relay may be going bad. I'll also be checking the grounds as I've seen a poor ground cause lots of different problems.

My alternator appears to be charging properly as it shows a short charge after starting and a discharge when I turn on landing lights but comes right back up...though occasionally, I have had the "waving ammeter needle"...again intermittently which I've been unable to track down.

So, I'm open to whatever suggestions folks might have on possible problems and where to start.

lr172 10-13-2017 10:25 AM

Do a load test on your battery. You can buy an inexpensive carbon pile load tester at HF. Experience has shown that SLA/AGM batteries, like the odyssey and power sonic, do not do well with constant trickle charges. The charger has likely destroyed your batteries capacity. It starts well when just off the charger, but is not recharging properly with just the alternator. The trickle charging is masking the capacity issue. The trickle charge get the battery up to a decent level, but it loses it quickly, as the core capacity is not there to hold a charge.

the power sonic has a VERY low internal discharge rate and there is no upside, but plenty of downside, to using a trickle charger. If your battery sits for more than 6 months, just top it off with a traditional battery charger. These are not the same a flooded lead acid batteries.

You may be able to bring back some life a few deep cycle discharge/charge cycles with a proper battery charger.

Does your starter have a solenoid that pulls the bendix drive into engagement? If so, that also could be failing and heat is making it worse. If it is an inertial bendix, I would not expect problems only with heat. I would expect the opposite.


JimRice 10-13-2017 10:30 AM

I'm not the builder so I'm not sure about the Bendix.

THanks for info about battery. May pull it this evening and see about doing a discharge/charge and see if that makes a difference. Though the pain to pull my battery might be cause for simply replacing the battery! :)

Tracer 10 10-13-2017 11:41 AM

“Battery Tenders”
Using a battery tender is the quickest way to ruin a battery. What happens is that the battery develops a “memory factor”; and slowly loses its amperage capacity. Even though a charger may indicate the battery is fully charged; it will actually be at 20-25% of full charge & not be able to start the engine. It may crank over when the engine is cold (lower compression & less internal friction); and will fail to when the engine is hot. And that may not be at your home Airport; leaving you stranded.
We are just now replacing our Concorde battery in our RV6; and it was installed in 2004. This battery has never been on a “Battery Tender”. It was only charged for 1-2 hours; if we had not flown for 30 days—which was not often.
Invest in a charger specifically designed for these batteries—Vans sells them.

170 driver 10-13-2017 12:00 PM

If you have an edrive starter, the early models of this had a dropout circuit in them and would quit when the voltage dropped too low, I had this problem, sent it back to them and they fixed it free. That's been a few years back now so things may have changed.

JimRice 10-13-2017 12:06 PM


Originally Posted by Tracer 10 (Post 1210807)
Using a battery tender is the quickest way to ruin a battery.

Tracer 10/Chief, thanks. I guess some things never change. I've been retired from the Army 14 years myself. Seems I still need wise CWO advice from time to time. I was a RedLeg and worked with a bunch of CWOs in Maintenance and Target Acquisition. Were you an aviator? I was FSO attached to 11th Avn Regt for a couple of months in TF Hawk/Albania. :D

JimRice 10-30-2017 09:27 AM

New Battery
The stars finally aligned and I finally had all the following; battery (vendor sent wrong one first time), free time and tolerable weather.

I replaced the battery yesterday. Cold start was fine, but hot starting while improved still wasn't 100%. When I was restarting after fueling up at a nearby airport, it turned a couple of blades, fired (kicking the bendix out) but didn't catch. On next attempt, it turned 2 blades and kicked out like before. I let the starter wind down and waited a couple of minutes and tried again. It turned twice and kicked out and then on next attempt, turned like normal and started up.

So, the battery, wasn't the sold culprit. I assume it wasn't putting out quite optimum power, which coupled with other issues, caused the problem. Consequently, I've ordered new Master and Starter solenoids and diodes for each. I'm going to replace everything since I'm about to begin the Condition Inspection anyway. Seems the inconsistent performance could be due to a relay contactor arcing/not making good contact. All the new parts cost less than $70 and the originals have over 1000 hours. I'll have to also check the resistance of all my battery cables/starter cables as well to make sure they aren't the problem, but visually, they all look fine. All grounds/attachments also checked good, but will be double checked during replacement of solenoids.

The starter appears to be fine given it cranks normally most of the time...when it gets sufficient power.

I was able to resuscitate old Power Sonic battery by significantly discharging and recharging a couple of times. It now checks as well as the new battery when both are fully charged. Still, given the cheap price and pain to change, I went ahead and installed the new battery. I don't trust the old one. It will likely end up on my lawn mower.

JimRice 03-03-2018 08:52 PM

Still Kicking Out
So far, I’ve tried about everything and still having problems. New battery, new cables, new master and starter solenoids and took starter to local armature shop and they say nothing is wrong with starter, yet I am still experiencing same problem. I’ve cleaned and reconnected all connections. After 2-3 blades, the bendix kicks out. Motor continues turning normally, but Bendix disengages. Occasionally, I’ll get 6-8 blades before it kicks out.

Today, after changing cable from starter solenoid to starter with #2AWG welding cable and new heavy terminals voltage drop during cranking was 0.4 volts from 12.5 to 12.1V . Voltage drop on ground side was only 0.15V.

Despite what armature shop says, I think I have an internal starter issue. I guess next step is a new starter. My starter is a Delco-Remy Prestolite. I don’t really want SkyTech or B&C lightweight starter because I need the weight up front the old starter provides. I already have the Landoll balancer ring.

Anyone know a shop who will rebuild an old starter? Not sure I want to take back to same local shop who said nothing is wrong. Not sure they will want to rebuild it. They have done a good job for a couple of friends so I know they are capable and are reasonably priced. They charged a friend $100 to overhaul his. It is sitting on a shelf as a spare for his RV-4 since he bought a new Skytec for his Cherokee. I am going to ask to borrow it to see if it works to confirm mine is bad.

This is last thing between me and finishing Condition Inspection completetion. After a cold wet winter and record rains recently, I’m finally about ready to fly after being grounded for two months. I’m open to suggestions on about anything.

Yen 03-04-2018 12:45 AM

Is this kicking out happening when the engine fires? If so I would suggest that a check of the mag timing may be a good idea, maybe the retard is not working correctly.

pa38112 03-04-2018 07:11 AM

Sounds like you have changed everything except the actual part that is giving you a problem. The alternator shop is probably correct - the electrical portion of the starter is fine; however the mechanical portion that engages the pinion gear is what sounds like the problematic area.
I would disassemble, clean, and lubricate that section - looking for any broken parts. Be sure to use the proper lubrication (from memory I think silicone ?).

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