belt squeals upon starting

I hear an annoying squeal when starting my SuperCub. It is variable. Sometimes no squeal at all. Other times just a few seconds, and sometimes it lasts longer(never more than 30 sec). Anyone have tips on how to handle this condition? It is primarily annoying because the airplane starts reliably.:-?

First did you put a high amp alt. On in place of a generator? Or just increased the amp out put of the alt? When you start it may be putting out a high amp to recharge the battery. Try putting a jumper box on and start the engine, see if the squeal stops. Also try starting with the alt. Off then after the engine is running stable try putting the alt. On line and see what happens. Just a guess, good luck.

Get a bar of soap. :lol:

Glenn

Ah! The cry of the Winter Weasel common to the North, cold engines, stiff belts, and long starts draining the battery. Sometimes tightening the belt helps. Sometimes the belt and alternator pulley are worn requiring replacement. They often end in Road Snakes that litter the highways in cold weather as the belt sheds it's skin.

Belt dressing can help but it can attract dirt.

Edit: I have on occasion dressed the pulley(s) groove with a fine abrasive pad like Scotchbrite to un-polish the surface. Once worn smooth they can slip more. But soon the belt bottoms in the pulley groove through wear to the sides and replacement is required of some components.

GAP

As Gary says, check belt tension, and if a bit loose, tighten some. That's about the only thing that squeals up front, hopefully.

Road snakes.....boy do I remember that winter! Damn!!

MTV

Mine did that right before the alt front bearing went out. Might want to take a good look at belt tension and even closer at alt/gen summer flying will be here soon, now is the time to do the work.
DENNY

Good point on the bearings. Might have a knowledgeable appliance mechanic look at that part when it's exposed.

I used to eat belts on IO-520's but they never let out a death squeal I could hear. Some would jump around quite a bit at idle when observed with the cowl off. I was advised to start the engine with as little electrical load as possible and alternator off. Then bring it online and wait until the ammeter showed a decline and voltage rose before adding a load. Not sure if that advice was valid as it could induce a sudden voltage spike in the system, but did as I was told. Sometimes.

Gary

replace glazed belt with new belt

Don't all conscientious Cub/Lycoming owners have a replacement belt ty-rapped to the front of the engine ready to install? Saves removing the prop to gain access.

EDIT: Removing the prop and starter ring gear/balancer assembly and installed belt allows placing the new/potentially replacement belt over the crankcase nose and tied to the engine lifting saddle aft of the front. When required cut off the old belt if still connected and install the new item without nose bowl/prop disassembly.

GAP

Or you could install a gear driven alternator. No belt = no squeal.

Web

I have a Field Approved gear driven B&C 12A on my C-85 (http://www.bandc.aero/gear-driven-alternators.aspx). Does what it's sposed to do. The only belt in the plane's around my waist. Plus suspenders just in case.

Gary

I thought it was clean underwear you were supposed to carry "just in case".

I bit of drift here but in my case the waist belt's 40+ years old. It's been dependable, never stretched, and is always there when I need it. However, just in case the suspenders are worn as backups. Wouldn't want to have a belt failure during a ramp check would we? Haven't worn underwear in years when flying. Too much risk for a wedgie at a critical phase of flight.

Gary

Thanks for chiming in with the suggestions. :smile:

Putting that spare belt on the engine just means you have a dried out crappy belt to put on. Pulling the prop is easy and the best way to get things adjusted properly.
DENNY

While the spare belt will age normally similar to the one that's installed on the alternator (both are exposed to heat and the elements), have you ever been out in the middle of the bushes and have one fail? And then not have all the tools and time to deal with the spinner, prop, in addition to the alternator? Having to remove and reinstall a prop plus a belt in winter or on floats parked on a mud bar in a remote situation might be someone's choice, but not mine. After having done so twice with it already available inside the prop makes me want it that way. Once returning to the comforts of town sure a new belt can be dealt with. Just one of aviations choices I guess.

Edit: For fill one was on a PA-18 at a winter camp after having a lightweight alternator installed (early Field Approved pre-B&C type). The Alternator pulley might have been small (car alternator then) and the belt broke I assume trying to keep up in the -30 temps. Top cowl, sides, bottom off and the spare belt installed. No battery charger at that time in camp and needed to finish trapping season on remote lakes before it closed. Second was on a Citabria with 80" constant speed prop on floats. Cowl comes off easy, prop not so much. Belt had lost a portion of the rubber V and was making a racket threatening to take out the alternator and bracket. Spare went on easy despite the mud bar.

Gary

I have changed a prop on a sandbar, but it was not because of the belt
DENNY