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Kubota D722 Slow/Hard Cranking

bgaidan

bgaidan

Red Skull Member
Joined
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NC Triad
I'm a little baffled by this one.

I picked up a few Woods (Grasshopper) mowers from a surplus auction a couple weeks ago. They're the same as my tired Grasshopper 722D so I was hopping to get at least 2 good running mowers out of the lot and sell/scrap/part anything that won't run. They were fairly low hour machines - 900, 700 and 400 hours. My grasshopper has well over 2k hours on it and likely way more since the hour gauge wasn't working when I bought it :homer: so I figured there's a good chance these will be serviceable.

Any way, they have the Kubota D722 diesel that's been used in a ton of tractors, mowers, generators, etc. I tried hooking a jump pack and a big battery to each of them and they all had the same symptom - slow turning over, starter kind of spazzing and clicking and generally not turning over fast enough to fire. Typical symptoms of a dead or dying battery...but definitely wasn't the case.

I pulled one in to the shop last night so I could start tearing in to one at a time and figure it out. I hooked my 300a jump/charger to it and still got the same result. I hooked jump cables straight to the starter to rule out bad battery cables. I pulled the starter off to bench test it and make sure it's not obviously shot. Seemed to spin up fine on the bench.

Today I pulled the injectors and 1) verified that the injection pump is working (it is) and 2) cranked it over with them in and it spun over quickly and smoothly.

It's almost acting like it has a compression release that's not opening, but everything I'm reading says these don't have a compression release.

I dumped some Marvel down the holes to let it soak for a bit and will be putting the injectors back together shortly, but I'm kind of cornfused at this point.

Ideas?
 
Are you sure some monkey didn’t put a 24vstarter on them?

Get one rebuilt and see if it fixes it.

I would bet the solenoid contacts on the starter is shot from being started on a low voltage battery.
 
I was gonna say maybe you got the most lucky and all of them have bad starters?

Or hyd pumps are WFO stalling them?
 
ThePanzerFuhrer said:
Are you sure some monkey didn’t put a 24vstarter on them?

Get one rebuilt and see if it fixes it.

I would bet the solenoid contacts on the starter is shot from being started on a low voltage battery.
Click to expand...
CarterKraft said:
I was gonna say maybe you got the most lucky and all of them have bad starters?

Or hyd pumps are WFO stalling them?
Click to expand...

I did already order a starter. Just in case. My mini has the same engine so that would make 4 (plus a spare sitting on the shelf in the shop), I figure it wouldn't hurt to have one around any way. :laughing:

Forgot to mention it, but did already disconnect the shaft to the pumps to rule them out.

Just buttoned the injectors back up and it's doing the same thing.

Edit: Uploaded to YT




It really does act like a bad starter, but the chances that all 3 have bad starters seems slim. Then again, they've supposedly been sitting for 5-6+ years so maybe that's common for these. :confused:
 

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have you tried grounding to the starter motor end cap rather than to the block or whatever?

The brushes actually ground to the end bell of the motor itself, so if they get corrosion between all the stacked bits it can make for high resistance in the ground circuit
one reason all the really big starters have the ground cable hooked to the endplate of the motor
 
[486] said:
have you tried grounding to the starter motor end cap rather than to the block or whatever?

The brushes actually ground to the end bell of the motor itself, so if they get corrosion between all the stacked bits it can make for high resistance in the ground circuit
one reason all the really big starters have the ground cable hooked to the endplate of the motor
Click to expand...

I've tried clamping the ground right on to the body of the starter. No change.
 
bgaidan said:
Solenoid seemed to fire fine on the bench.
Click to expand...
no load on motor means almost no amperage draw
no amperage draw means shitty connections don't matter as much

need a lot of amps flowing through stuff to see what the actual voltage drop across the shit will be, nomtombout?
 
clack the solenoid with one hand and hold it engaged, and then apply your + jumper cable directly to the wire that goes to the starter motor rather than the battery side of the solenoid
 
Not much rebuildable here. Can't even take the brushed out of the motor. Starter is a Mitsubishi reman, so someone's already been here.

If I can find a part number for the solenoid, I'd try replacing it. Otherwise, new starter should be here by Wednesday.

1726523637749.png



I did find the one from the Grasshopper that I replaced last year. And now that I think of it, it may have had similar symptoms. :homer:
1726523681908.png



And then went and pulled the one off the spare engine I got form a generator, but that one was a different configuration from the equipment type ones and the starter isn't compatible.
1726523753770.png
 
CarterKraft said:
The chattering is odd, thats like its dropping voltage to the coil.

New starter fixes this 100%:grinpimp:
Click to expand...

I'm on board with that theory now. The fact that all 3 do it still bugs me. But I kind of wonder - I've seen auto parts stores say they won't warranty a new starter if it's installed in a vehicle with a bad battery. I wonder if feeding the solenoid low volts or not enough amps can fry them? If these all had bad batteries and somebody fucked with them, they may have fried all of them.
 
bgaidan said:
Not much rebuildable here. Can't even take the brushed out of the motor. Starter is a Mitsubishi reman, so someone's already been here.

If I can find a part number for the solenoid, I'd try replacing it. Otherwise, new starter should be here by Wednesday.

1726523637749.png



I did find the one from the Grasshopper that I replaced last year. And now that I think of it, it may have had similar symptoms. :homer:
1726523681908.png



And then went and pulled the one off the spare engine I got form a generator, but that one was a different configuration from the equipment type ones and the starter isn't compatible.
1726523753770.png
Click to expand...
If you really want to find out isolate the motor lead from the solenoid.
We are thinking the contacts to jump B+ to motor + are fried.
 
bgaidan said:
I'm on board with that theory now. The fact that all 3 do it still bugs me. But I kind of wonder - I've seen auto parts stores say they won't warranty a new starter if it's installed in a vehicle with a bad battery. I wonder if feeding the solenoid low volts or not enough amps can fry them? If these all had bad batteries and somebody fucked with them, they may have fried all of them.
Click to expand...
My starter rebuilder constantly is harping about low battery voltage. You lose a few volts and the amperage has to spike to make up for it. This then burns the contacts out on the solenoid
 
CarterKraft said:
If you really want to find out isolate the motor lead from the solenoid.
We are thinking the contacts to jump B+ to motor + are fried.
Click to expand...

Half-ass tried this. Engine still turning over slowly, but eliminated the clickedy-clackady of the solenoid going on and off. The the best setup with the clamps of my jump box being pretty clapped out and the wire I was sing to jump the solenoid started getting a little melty. :laughing:

Probably just best to wait for the new starter to show up now. I'm going to pick up a new battery this week too so I can eliminate anything with the jump box or cables.
 
Heh....doing a little digging on ebay and finding part numbers to cross, I just found the starter on Amazon for $35. :lmao: I kind of question some of these, but the part number checks out. 🤷‍♂️

1726527243231.png


Also found the solenoids for $20 so may give one of those a shot and see if I can revive any of the 4 questionable starters I now have.
 
[486] said:
unless if its like my textron where the safety interlock ecu controls the starter, making it chatter when the battery is weak
Click to expand...
Zero computers or fancy electronicals on these things.
 
bgaidan said:
Not much rebuildable here. Can't even take the brushed out of the motor.
Click to expand...
brushes are under the endcap
I was figuring they were the denso style ones, those crimped together solenoids aren't easily fixable
 
Those starters tend to suck. The newer type off your generator are much better.
 
Mine does the same thing, use a big screwdriver to bypass the solenoid. Works every time
 
Dethmachinefab said:
Those starters tend to suck. The newer type off your generator are much better.
Click to expand...

The generator one is clocked wrong and the solenoid would hit the engine base plate. But I did realize the one I ordered off ebay is that style but clocked 180 so it might just work. Otherwise I have the $35 Amazon one on the way too.
 
If it’s not the starter then maybe some sorta fluid in the cylinders to almost but not quite hydrolock? But leaning towards bad starter from non op glow plugs
 
bgaidan said:
The generator one is clocked wrong and the solenoid would hit the engine base plate. But I did realize the one I ordered off ebay is that style but clocked 180 so it might just work. Otherwise I have the $35 Amazon one on the way too.
Click to expand...
I normally rob the nose piece off the old one if that’s the issue.

If it crosses with a sd-7.3 truck, can you do the upgrade to the 6.0 starter too? Those starters are famous for being slow.
 
Just throwing this out there. My John Deere small diesel tractor had a starting issue where it would intermittently not want to start. Battery was good, I cleaned terminals, etc., but occasionally would act like it had a dead battery and just click the solenoid. Did some Google research and found it was a somewhat known problem on not just my tractor but many other older engines where there was not a starter relay. Also, the age of the wiring is thought to be an issue. My tractor is an '86 model. I bought a kit off Amazon for ~$30, installed it (pretty simple install) and I have never had a problem since. Here's a link to the thread I found:
www.greentractortalk.com

750 won't turn over but it will run

www.greentractortalk.com www.greentractortalk.com
 
Update:

Ebay starter showed up. Slapped it in along with a new battery and she cranked right over at mach fuck. Fired right up. :smokin:

Hooked the prop shaft back up and seems like the pumps are working. Drive tires are bald and one is off the bead haven't been able to take it for a spin.


Got two other starters on the way. If the others are the same fix, I got a :smokin: deal.
 
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