Alternator Belt Problems

soarohio

soarohio

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soarohio
1975 C182 with 0-470-s engine.

I have had three alternator belts in the last 150 hours. The first one shredded but the last two have come off with no apparent damage. My partner has not had a belt come off when he is flying, and we fly about the same amount of time. Not sure why it is happening when I’m flying.

The alternator is due for an overhaul but our mechanic does not think it is the problem. The pulleys appear to be aligned. Is there anything else we should be checking.

How long are alternator overhauls taking now?
 
You likely have the shock-mounted alternator, and the rubbers are worn out. Continental went away from that setup due to that. The alternator moves too much under vibration.

If you have a three-bladed prop, some guys have been able to stop belt-throwing by reclocking the prop 180 degrees. I don't know why it should work.
 
More, commonly look at youre alternator case for bearings loose in the case. If loose you'll be astonsihed that you got 50 hours out of each belt.....(lessee, how did I learn that...?)
 
In edition to what others have mentioned... Check the belt tightness. The test is not performed like automotive applications, It's a torque test by using a torque wrench by turning the nut on the alternator.

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UUh, the instructions you posted say that belt tension is tested exactly like on a car. Press on the belt and see how much it deflects.
 
Yes. I don't see anything about applying torque on the alternator but to apply 12 pounds of pressure to center of belt for deflection. Or is it 12 pounds of pressure to the prybar?
 
Many times an alternator belt is seriously overtightened. As the engine and alternator get hot, metal expands and the belt gets even tighter.

Overtightening a belt causes bearing wear and can even cause the belt to flip on the pulleys ...
 
Could be the shock mounts, they tend to wear out and cause the alternator to wiggle too much. Also, make sure the belt isn’t too tight, too much tension can mess with everything when the engine heats up. And yes, check the alternator bearings too.
 
Detuning of Dynamic Dampers has always been sort of a mystery to me.

It can be caused by a prop strike , rapid throttle movement and other

factors. Just don’t comprehend the HOW and what actually occurs.
 
We had a second A&P look at it. Everything appears to be aligned, tension seems to be fine, bearings in alternator appear to be ok and the mounts appear to be in good shape. He tightened the tension a little bit. The belt came off after 3 hours. The belt is flipping inside out and remains hanging on the motor pulley.
 
soarohio said:
We had a second A&P look at it. Everything appears to be aligned, tension seems to be fine, bearings in alternator appear to be ok and the mounts appear to be in good shape. He tightened the tension a little bit. The belt came off after 3 hours. The belt is flipping inside out and remains hanging on the motor pulley.
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Take some pictures of your installation and post them here.
 
How many hours on the 470? We have a 1967 182 and have been dealing with this issue for about 5 years. New Alternator and mounts, new pulleys. Unrelated, but also a new 3 bladed McCauley prop. Old was also 3 bladed McCauley. Sometimes it comes off after 50-60 hours, other times 3-5. Club plane with 8 members, but no one can come up with an operational aspect that could cause it.

Maint officer and mechanic have both spoken with Continental, and appears to be the crankshaft counter weights. They do wear and then can cause belt throwing. Ours started throwing belts at about 1,100 hours. Topped the engine at about 1,250 hours, (not due to the belt) and now at 1,750 we have put a deposit for a factory reman from Continental. Should be installed in May sometime.
 
Cricket1 said:
How many hours on the 470? We have a 1967 182 and have been dealing with this issue for about 5 years. New Alternator and mounts, new pulleys. Unrelated, but also a new 3 bladed McCauley prop. Old was also 3 bladed McCauley. Sometimes it comes off after 50-60 hours, other times 3-5. Club plane with 8 members, but no one can come up with an operational aspect that could cause it.

Maint officer and mechanic have both spoken with Continental, and appears to be the crankshaft counter weights. They do wear and then can cause belt throwing. Ours started throwing belts at about 1,100 hours. Topped the engine at about 1,250 hours, (not due to the belt) and now at 1,750 we have put a deposit for a factory reman from Continental. Should be installed in May sometime.
Click to expand...
 
1250 SMOH. 800 since the engine was removed and had an IRAN before we purchased the plane. The counterweight bushings and pins were changed at that time.
 
soarohio said:
We had a second A&P look at it. Everything appears to be aligned, tension seems to be fine, bearings in alternator appear to be ok and the mounts appear to be in good shape. He tightened the tension a little bit. The belt came off after 3 hours. The belt is flipping inside out and remains hanging on the motor pulley.
Click to expand...

Belt flipping is usually caused by too much tension (see post # 8 above). Once it has flipped it will need to be replaced ...
 
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NordicDave said:
In edition to what others have mentioned... Check the belt tightness. The test is not performed like automotive applications, It's a torque test by using a torque wrench by turning the nut on the alternator.

View attachment 140120
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Wrong instructions. This is from a 172 manual and could apply to just about any 60-amp alternator:
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One has to hold the prop still while you do this.
 
soarohio said:
We had a second A&P look at it. Everything appears to be aligned, tension seems to be fine, bearings in alternator appear to be ok and the mounts appear to be in good shape. He tightened the tension a little bit. The belt came off after 3 hours. The belt is flipping inside out and remains hanging on the motor pulley.
Click to expand...
You need a mechanic that will consult the parts manual and see what's wrong with the setup. There are at least four versions:

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Sometimes generators get replaced by alternators, and the mechanic will use a bunch of junk washers or spacers and a long bolt to make it fit. Sometimes parts wear out and the mechanic uses stuff from another setup to fix it. Mixing and matching this stuff doesn't work and results in all sorts of problems including belt failure and alternator bracketry damage and failure.
 
100% what @Dan Thomas just mentioned as well as closely follow the tensioning procedures in the Service manual. It's not just "pull it tight, torque-in the mount, and see if the belt is squishy enough".
 
Did not see any damage to the pulleys. The pulleys turn true. Hopefully the regular pattern will give our mechanic and idea of where to look.
 
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