Request:
I'm in remote Baja and my (stock) starter has quit engaging with the flywheel when I pull the start handle. The starter whirrrs away, but doesn't turn, or engage the engine.
Any advice would be helpful here in Mulege, 1/2 way through this trip.
Many Thanks, Berk - 1959 stock C-172 (Cont. 0-300 engine)

Could you hand prop it and fly to Loreto?
I assume you're doing a whale trip? If so Jack usually has a SAT phone.
I wish I could tell you what to do to engage the starter. I assume you've checked all the electrical connections on the back of the starter? Do you have tools to remove the solenoid? As a last ditch effort you might try aggressively rapping on the side of the starter, maybe the throw out gear is gummed up with Hotel Serenidad dust.
Is there someone I can call for you?

Glad to here that you made it out of Nor Cal. Beter to have the starter problem at Mulege than at Punta Sanfrancisquito. I would do a post on Baja Bush Pilot Forum. There is always somebody comming down that reads that forum. Anyway, it sounds like the bendix drive on the starter motor.

You should be able to hot prop a 172 pretty easy. Put a few rocks in front of the wheels. A 172 in Weed, CA took off without a pilot aboard and the plane is scrap now.

Tim Avery

Hi all:
Any advice would be helpful:
We've been hand-propping, with great care, and it works okay, but takes some of the spontenaity out of flying for me. (I can't take a solo sunrise flight, unless someone is available to help with the hand-propping).
I took all the connections apart, and scraped 'em shiny with my knife, and rapped on the starter with the original hammer (rock). Tried moving the prop w/ the key off, to change position on the flywheel, and also hand pushing the gear plunger, but nothing seems to work.
I used to have an old VW van that I had to wiggle underneath to bridge two terminals with a pliers to start the beast, but it's been 3 decades, and I don't recall which terminals to bridge - is it the large ones on the solenoid?
We're independently traveling 'round Baja for our first time, and loving it besides this starter problem.
Thanks for any ideas...Berk in Mulege

Berk, it sounds like you have an O-300 engine with the pull-to-start knob on the panel? If so, there is no "starter solenoid". There is a starter motor,which sounds as if it's turning just fine by your description. And there is a so-called starter clutch (pinion) which is what you are physically engaging when you pull the starter knob. The last little bit of travel in the linkage engages the starter button on the side of the starter motor. So your starter turns, but the engine doesn't-- sounds like a starter clutch problem to me.
After a bit of thought, I realized that it may be just a case of an out-of-adjustment starter linkage. It must fully engage the starter clutch (push it into the accesory case) before activating the starter button. If it is out of adjustment, it can damage the starter-clutch gear &/or the gears inside the accesory case, and the resultant debris will go into the oil.
If the linkage appears to be adjusted right, but the starter still isn't engaging, be advised that these starter-clutches have a Sprague clutch & bearings inside them that can come apart- again, debris gets into the oil. I had this happen on a key-start 150 I used to own. The key-start clutches are more prone to catastrophic failure IMHO than the pull-start models, but they can come apart too.

Eric

zero.one.victor wrote:Berk, it sounds like you have an O-300 engine with the pull-to-start knob on the panel?...If it is out of adjustment, it can damage the starter-clutch gear &/or the gears inside the accesory case, and the resultant debris will go into the oil.
If the linkage appears to be adjusted right, but the starter still isn't engaging, be advised that these starter-clutches have a Sprague clutch & bearings inside them that can come apart- again, debris gets into the oil.
Eric

Ooooo, not good. A few hours earlier, the starter cable had broken a couples of inches from the end, so I had to jury-rig it by pulling the lever closer to the broken cable end, and re-fastening it. - Would that put it "Out of Adjustment"? There is currently about 1/8" clearance between the end of the lever and the starter button, on the starter. Would that create the no-starter-engagement problem? If the parts have come apart & become adrift in the oil, will my remote-mount oil filter sift out the parts before they can do damage? Is there anything that I can do at this point to fix it in the field?
I hear that the only mechanic in this area is across the Sea of Cortez (about a 50 mile flight over open water).
Any advice is surely much appreciated. Many thanks, Berk

Are airplane starters like car starters? In a car starter motor, there is a clutch-like device called a "Bendix" which is a helical gear that is deployed with centrifugal force. The starter motor spins and throws the gear out, and it engages the flywheel. When you let off the switch and the electric starter motor stops spinning, the Bendix retracts and disengages from the flywheel ring gear.

Since there is no solenoid, and all the current is being switched mechanically, the only problems I can see are the connections (not get full current) and the Bendix not spinning out to the ring gear.

Z

Edit: This "Bendix" I believe is what SuperDave is calling a pinion gear in his post below. I think Bendix is a brand name of something or other, so "pinion" is probably more accurate.

In pull start systems the pilot engages the pinion gear by pulling on the cable. Your cable broke and you rigged it-now it doesn't work. I would de-cowl and remove the starter. You will see a shaft with the pinion gear on it. At this point it will become obvious how it works. The only thing of importance is that the engine not drive the starter all of the time. It sounds like the starter runs but the pinion gear is not engaged but I would check to make sure everybody still has all of thier teeth and that they are not swimming around in the oil. I think in the process you will discover what the problem is and be able to get it working again. Good luck

Berk, without seeing your starter linkage I'm not sure if it's rigged OK or not. The starter lever should not touch the pinion at all in the at-rest position, you should have about 1/16" clearance. The lever should push the pinion into the accesory case 7/16" before it pushes on the starter button,total pinion travel should be 9/16" (another 1/8" after button is engaged). You should also have a return spring on the linkage.
When you re-rigged things after the starter cable broke, I'm wondering if that caused the starter clutch to continually engage the crankshaft gear, and caused some sort of failure. Normally the engine overruns the starter after the engine starts but only until the starter knob is released-- in other words, for just a second or so at each engine start. Continual engagement (not designed for) could bring on a failure. I can't see how you could have just pulled the lever closer to the broken cable & reattached it & still have it adjusted properly. I had a similar cable breakage, but reconnected the starter lever by using a sort of floating link to extend the broken cable. I was very careful to get the linkage adjusted right, per installation instructions by Canadian Aero Mfg who made the starter clutch.
I'd be pretty leery of running the engine any more before checking it out further. I'm with Dave, I'd pull the starter & check out the gear teeth & see if the starter clutch seems to be malfunctioning. Hopefully if the starter clutch is gunnysack it hasn't come apart or chewed up any gear teeth.
Zane, the bendix system you descibe is pretty much what Lycomings use, ring gear & all (mounted behind the propeller). The Continental system is naturally superior (like everything else Continental ) but does require proper adjustment. I think lots of people get in trouble by not replacing the starter clutch at engine overhaul time ("ah, it's working OK"), then when it fails later they're surprised.

Eric

zero.one.victor wrote: When you re-rigged things after the starter cable broke, I'm wondering if that caused the starter clutch to continually engage the crankshaft gear, and caused some sort of failure...Continual engagement (not designed for) could bring on a failure...I'd be pretty leery of running the engine any more before checking it out further. I'm with Dave, I'd pull the starter & check out the gear teeth & see if the starter clutch seems to be malfunctioning.Eric

I pulled the cowling, and disconnected the starter cable, which allowed the actuator arm to return the starter gear plunger to the "at rest" position. Without a new gasket & sealer available, I did not think that dismantling the starter & acessory housing would be wise, because of the likelyhood of oil leakage. I drained the oil, and looked for signs of metal, but found none. Since I do not have a replacement filter, I left the filter in place.
I guess that hand propping will have to be the norm for the rest of the trip. Fortunately, one of my friends is an expert at hand propping.
Thanks much, Berk

So Berk, did you ever get your starter troubles squared away? How about filling us in.........

Eric

zero.one.victor wrote:

zero.one.victor wrote:So Berk, did you ever get your starter troubles squared away? How about filling us in.........

Eric

Maybe he's still in Baja, posting from the local taqueria?

zane wrote:

zero.one.victor wrote:

zero.one.victor wrote:So Berk, did you ever get your starter troubles squared away? How about filling us in.........

Eric

Maybe he's still in Baja, posting from the local taqueria?

Yes. Pete, and John, and I hand propped it for a week or so, 'til getting home. It turned out that the starter clutch had fried. Common prob w/ the old 0-300. No other damage, thankfully.
It's so nice to just pull the handle now, from inside, instead of the whole ritual of being up close & personal with the giant horizontal human blender.
Went up to the Lava Ice Caves in Sun River, Oregon last week. They're a short walk from the airport there. Quite cool. Literally - (bring a jacket.)
Enjoy this high pressure! Berk

It's Zona.

Long time no see. Glad you got back safe from your trip.