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Grasshopper 721D Motor drags


etabor's Avatar
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06-24-16, 07:09 AM   #1  
Grasshopper 721D Motor drags

I have a grasshopper 721D with a 3 cyl Kubota Diesel. I noted a slipping deck belt when mowing one day and stopped. When I got off, I noted electrical smoke coming from the dash area. Since then, the started drags and will not crank the engine fast enough to start it. I have checked the fuses, the 30 amp fuse listed as REG has a terminal that seems to have gotten hot, I cleaned that up and reinserted the fuse, have 12 volts to both sides. No other wires are burned or corroded. Put a new battery in it, the old one had a few years on it, put the old one in my pickup, starts it fine. Replaced the + and - battery wires as the originals looked iffy. Still no fast crank. Had the old starter looked at, was told it was bad and not rebuildable, had it replaced. Still slow crank. Took off fan belt, alternator seemed tight but not tight enough to cause issue. Left belt off, same issue. Have not yet taken hydraulic drive belts off you and am at a loss. HELP!

 
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06-24-16, 07:37 AM   #2  
Take off all the accessory belts and hydraulic belts see if it will crank. Does the alternator spin freely by hand? Something outside the engine is messed up.

 
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06-24-16, 11:29 AM   #3  
I am thinking PTO clutch .


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06-24-16, 12:17 PM   #4  
PTO Clutch is unhooked and not engaged. I will pull it off though and see if that helps.

 
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06-24-16, 12:22 PM   #5  
Removed fan belt and Alternator is very tight but starter still drags. I did take the starter off and he found the spec for the starter gear is 29.8 mm and this starter mics at 29.0 mm. He could not find the old starter drive gear. He is ordering another starter for monday....and I pray.....

I also cut out the bad fuse and put in an inline fuse in the REG slot. I hope this fixes the burned connections.

I am soooo frustrated. I fancy myself a decent troubleshooter but this has me by the "short n curley."

 
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06-24-16, 02:30 PM   #6  
When you say the alternator is "very tight" are you saying it doesn't spin freely without the belt on it? It should and if doesn't there's something wrong there as well.

 
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06-24-16, 03:07 PM   #7  
If you have a belt still on the PTO clutch and a bearing is bad, the only way to take it out of the equation is remove the belt. Unpluged or not engaged won't heal a bearing or dragging clutch.
It may have been going out for a while and the starter just handled it, that would also explain the toasty terminal.

Dem pesky electrons can be the worse sort of gremlins! I had a grasshopper last week that would not crank at all. I could jump the starter an it would run so, starter good. Tried 12v to the solenoid terminal and nothing...changed the solenoid and no luck. Got the schematic out and grasshopper uses ground in the safety switch circuit instead of power. Jump the ground terminal on solenoid to ground and voila...had already tested all the switches and cleaned and reseated connections...got on the horn with support and traced the entire safety ground circuit out and it was starting to look like a bad solder connection on a circuit board in the console...kicked the damn thing around another half day before finding the bad connection on a spade terminal for the switch on one of the levers....my shop buddy and I have a move we do for gremlins or train driver????? We call it the horizontal bobble head


Just needs a bigger hammer
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Last edited by BFHFixit; 06-24-16 at 03:22 PM.
 
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06-24-16, 05:37 PM   #8  
May not be relevent, but my Kubota ZD 21 has been cranking normally lately, but I have noted the alternator light would stay on for about 5 seconds before I heard the alternator kick in. I have not checked it from a cold start, but I feel my alternator is going south. It will kick in and run and charge properly, but that little hesitation tells me something is amiss.

 
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06-25-16, 06:28 AM   #9  
Yes, it does not spin freely, but it is out of the equation with the belt disconnected.

 
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06-27-16, 01:11 PM   #10  
Got the other starter today. Once the rain storm stops will put in. Pray..........

 
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06-29-16, 03:18 PM   #11  
Got the starter on, had to shim the durn thing a bit, as when it cranked the motor the flex plate flexed and knocked the gears out of alignment. got the motor started...Yes Yes. Let it run a minute as the belt was unhooked then shut down and restarted. I see the starer only hits the flywheel with a 2 mm or less gear. Is still noisy. Took alt. off and ordered bearings, loud squeak. Once it comes back, will put together, reassemble sheet metal and MOW GRASS. Then I'm taking it to the starter shop and get the thing looked at. Not happy with the small bite the gears are taking. Also putting on new blade belts as the 1/2 x 36" seem to be too big. Anyone know what the belt dimensions should be for the belts on the blade clutch?

 
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06-29-16, 03:42 PM   #12  
Do you have the right bendix gear on it? When you're working on it see if the gear travels all the way to the end of the shaft when you spin it with the battery.

 
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06-29-16, 03:59 PM   #13  
I don't know the dimensions but I could get you a part number or if you have it find an OEM belt!
There are more dimensions to a belt than width and length. OEM, OPE belts are not standard dimensions and I have yet to find any aftermarket belt operate as intended. Simply put, it is better to do it once and be done with it.
Your deck has a separate model number than the tractor, should be a 4 digit number on a placard or sticker. Likely a serial number as well.
These decks are not married to the tractor so they have their own identity. If you have an owners manual it may have a parts list. Should be a 6 digit numerical part #.


Just needs a bigger hammer
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06-30-16, 06:28 AM   #14  
That is just the thing. I'm not sure it is the right Bendix gear. The starter shop looked up the starter and it says an od of 29.8 mm. Another source says 29. They lost/threw away the Bendix off of the original starter so they have no comparison. The starter I have is brand new but is not a Mitsubishi, possibly a Chinese knock off. (cost 139.00 with tax.) My plan is to get the Alternator back, assemble the mower, get the belts so they don't slip, mow non stop until done, then load on my trailer and take it to let them look at it.

 
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