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Discussion Starter · #1 ·
yesterday I was doing some heavy dirt moving with my JD 770. After about 45 minutes it started smoking.it was coming from the fan belt. When I touched the front of the pulley on the alternator and it was very very hot. My battery light was on also. Does anyone have a suggestion??
Thanks. Am smack dab in the middle of a build and need my tractor 馃槩
 

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Sounds like either the alternator seized or the belt got loose for whatever reason. Start by pulling on the belt with your finger, should deflect about 1/2". Next, remove belt from alternator pulley and rotate pulley. It should turn easily, smoothly, and without any grinding sound. Bob
 

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You can get by with No alternator.

Sadly you probly only have one belt and the water pump has to work.

Were you running lights??

As said..loosen alt. slip belt off and see if alt. is locked up.

If alt is fine check fan/waterpump......Theres only 2 choices of whats bad. Alt or WP......Typicly.

Unless your belt was way loose and your battery is bad or you were running lights to put a big load on Alt.
 

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Discussion Starter · #4 ·
my husband pulled the alterntor--YUK. it was seized. we ordered a new one online (went to JD-the wanted more than $350. found a 'no name' on line for $50!. will replace fan belt too from local auto shop, it's tough-i miss my tractor. we're excavating new property and need to move alot of dirt and grade a lot......hope all this works. just another question-could i have caused the problem by pushing the tractor to its limits? i was moving a large pile of dirt-pushed hard into the pile to get as much in my bucket as possible...bucket would stop and i needed to back up a bit in order to be able to get the bucket to move....i guess i may have been a bit too aggressive! rpm's were never over 2000

thanks, everyone for being my 'green buddies'....we're city slickers and learning the ropes!!!!!
 

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The 770 produces max power at 2600rpm, so you weren't really overworking the engine @ 2000rpm! The tractor is 25 +/- years old and parts fail all on their own! Unless you stood next to the tractor and threw hand-fulls of sand into the alternator, you did nothing wrong. Your alternator simply wore out!

Don't throw old alternator out! Dismantle & inspect, especially the bearing area. If you're lucky, the bearing simply seize and the belt slipped... and smoked! If the bearing bore in the housing is still in good shape... tight fit on OD of bearing... and the shaft is still in good shape... tight fit into bearing... you may be able to replace the bearing and have a spare alternator. Having a spare part is usually a good guarantee the part in use will never fail! Look closely at the bearing and you may see some numbers on it...thinking "6201ZZ". These will be available online, auto parts stores, or JD dealer part # M800123.

Bottom line, you did nothing wrong and you'll be up & running soon! Bob
 

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Discussion Starter · #6 ·
The 770 produces max power at 2600rpm, so you weren't really overworking the engine @ 2000rpm! The tractor is 25 +/- years old and parts fail all on their own! Unless you stood next to the tractor and threw hand-fulls of sand into the alternator, you did nothing wrong. Your alternator simply wore out!

Don't throw old alternator out! Dismantle & inspect, especially the bearing area. If you're lucky, the bearing simply seize and the belt slipped... and smoked! If the bearing bore in the housing is still in good shape... tight fit on OD of bearing... and the shaft is still in good shape... tight fit into bearing... you may be able to replace the bearing and have a spare alternator. Having a spare part is usually a good guarantee the part in use will never fail! Look closely at the bearing and you may see some numbers on it...thinking "6201ZZ". These will be available online, auto parts stores, or JD dealer part # M800123.

Bottom line, you did nothing wrong and you'll be up & running soon! Bob
Bob, you made my morning ! Thanks for all the detailed input and encouragement. I鈥檓 new to 鈥渃ountry life鈥 and tractors and am loving it all. I did order a new one online for $50. I couldn鈥檛 find any part number on my alternator but hubby found the replacement by sight. Vendor confirmed it. I鈥檒l go out and look for some numbers on mine and verify that we got the right one, too
Thanks again 馃尀
 

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An alternator simply goes around and makes AC electricity. I don't have a 770 and didn't get into too many of the details, BUT!

One item I did notice is that the original alternator is rated at 35 amps output, so your replacement should match that. Another item to be concerned with is does replacement have a built-in regulator and do you need one! Never mind! I just checked partscatalog.deere.com and the 770 has a regulator, so you should need just a plain alternator that produces AC volts. Next would be pulley! Does replacement have a pulley and the same size? If not, will yours fit? And last, will it bolt up to engine?

Many/most of these questions can't be answered until the replacement is in hand, but I just wanted to make you aware of possible problems! Bob
 
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