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Kubota Diesel Service Info


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#16 boostedbuick OFFLINE  

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Posted September 14, 2012 - 08:51 PM

Is there any reason why I would have to check compression through the injector hole? The diesel compression tester I have access to uses the glow plug holes. I figured for sure that I could, but never hurts to ask. Kubota manual says to use the injector holes.

I'm going to start with compression. If it's low or unbalanced I plan to tear it down and check EVERYTHING. If compression is good, then it's on to fuel delivery/timing.

#17 Cvans ONLINE  

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Posted September 14, 2012 - 09:38 PM

I am not a diesel mechanic but the only thing I can think of is if your injectors weren't holding you might get an inaccurate reading. I wouldn't hesitate to use the glow plug hole. I hope someone with more experience will chime in.

#18 Amigatec OFFLINE  

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Posted September 15, 2012 - 06:09 AM

It's possible there is some water in the injection pump. The filters won't stop everything. Some people dont change the filter when they need to.

#19 boostedbuick OFFLINE  

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Posted September 22, 2012 - 01:14 PM

IT RUNS!

With relatively little effort. I put fresh oil in it and primed the system using the 2 year old diesel in the tank. It seems to run fine under non load conditions. Shakes the hell out of the whole tractor. Revs fine, idles fine but again shakes the hell out of things. Had to leave it alone for the day but when I get a chance I will do a warm compression test.

#20 olcowhand ONLINE  

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Posted September 22, 2012 - 02:04 PM

Dump & replace with fresh fuel, along with a healthy dose of quality diesel injector cleaner. The shaking may clear up after a while. Slower speeds is where you'll see the most shaking, but again, it may clear up with new fuel & conditioner.
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#21 Cvans ONLINE  

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Posted September 22, 2012 - 07:54 PM

My Son in-law just purchased a G4200 that had been setting for 5 years. Needles to say it shakes pretty good when idling but started right up. I'm hoping by now that he has installed new fuel also. Nice to hear that yours is up and running.

#22 boostedbuick OFFLINE  

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Posted September 23, 2012 - 10:16 PM

Fired it up again today and finally figured out how to get it to engage and move under its own power. I don't know how much power its supposed to have but its certainly not running right with all the shaking. Couldnt test compression because I didnt have the right fitting but I'll ask around tomorrow.

I couldn't get it to die while driving it unless I sidestepped the clutch in 3rd while at a dead idle. otherwise it'd chirp the rear tire and take off. But it seems to labor a lot to gain rpm while in gear. Wish I had a normal running one here to compare it to. Never been around a small diesel, I don't have a clue what it's supposed to do. Sounds like it has a miss.

Gearbox pushes oil out everywhere when its moving. Continuously dripping even after 5 mins. Don't really care, no need for the box, but I thought it was odd. Comes out the shifter boot and if you pull the stick it flows out. Good clean oil smells like 90wt.

Rides like crap with no seat. Bout went off the back of it when I popped 3rd at full rpm. :dancingbanana: Would have been fun to get up and chase an unmanned half tractor running amok.

#23 boostedbuick OFFLINE  

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Posted September 23, 2012 - 10:19 PM

HA! Just noticed I'm a "contributor" now. Musta been the engine manual I uploaded. Best $12 I ever spent BTW.

#24 Cvans ONLINE  

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Posted September 24, 2012 - 12:12 AM

Here's a good video that should give you a good idea of how your mower should sound and operate. This sounds just like mine.

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#25 olcowhand ONLINE  

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Posted September 24, 2012 - 08:27 AM

At slower speeds, these twins do sound as though they have a miss, and they have shake at slow speeds even running perfectly. 3 cylinders are almost perfectly balanced, but not twins.
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#26 boostedbuick OFFLINE  

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Posted November 16, 2012 - 06:51 PM

Factory compression spec (converted from metric) is 448 psi with a 337 psi rebuild threshhold. The story of it being rebuilt must be true. first cylinder just touched 500 psi and the front cylinder hit 450 but it took longer. This was warm but not full operating hot by any means. the lower of the 2 cylinders had a lot of soot/carbon on the glow plug and I know the glow plug is working. I think thats the one thats not pulling its weight and I dont think that side of the motor was warm enough. It took me FOREVER to get the ambition to get the right adapter for the compression gauge and the d**n schrader valve was bad right out of the box. Had to procure another so I had to assemble and warm up and then do the test TWICE. Starting this thing in late fall is a chore.

Next is injector testing. Luckily my place of employment has a tester to test the popoff pressure of the injectors. Kubota manual has the spec as well as instructions to re-shim. I got a million things to do to my grand national as well as move from one garage to another and I plan to spend the winter working on the interior of my house. So updates will be few and far between but when I do something to it I WILL be back. I know everyone's on the edge of their seat waiting for the outcome LOL. NOT!

#27 boostedbuick OFFLINE  

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Posted November 22, 2012 - 10:40 PM

Injector popoff pressure spec is 2000-2150 psi. Got them to work this week and had the diesel guys play with them on the test fixture. Injector on the "suspected good" cylinder pops off at ~1500 psi but has good pattern and consistent popping operation. Injector on the "suspected lazy" cylinder gets to ~1800 but spray pattern is erratic and if you really lay the pressure to it, it sticks open and just sprays. We think it's washing the cylinder rings and is the cause of that cylinder beihng lower/slower on the compression gauge. Injector pump is in time as near as I can visualize using the timing marks on the flywheel, both sides shoot equally high toward the ceiling when cranking LOL. I found the part number for the shim kit assortment to re-shim the injectors to proper spec after a disassemble/cleaning. Basically rebuild them in house. $32 shipped for the shim assortment. Something every kubota owner should probably have checked/done. If this don't fix it, It's for sale!

BTW the rubber return hoses were so brittle, there's no way in hell anyone's even had them out of the tractor anytime recently, let alone an engine rebuild.

#28 boostedbuick OFFLINE  

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Posted December 12, 2012 - 07:24 PM

I cleaned and re-shimmed the injectors and plan to drain the old fuel before running. Guys at work told me to flush everything and replace both filters, they are worried about algae forming in stagnant diesel. I will probably replace the rear one and kerosone wash the front one.

I took some pics while redoing the injectors. If anyone wants to read about what I did/found when re-shimming I could do a write up with pics. You'd need to locate a tester to borrow/rent/use somehow. Once you got them clean (at home) you could swap shims out really fast at someone elses shop if they have a tester available.

#29 Cvans ONLINE  

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Posted December 12, 2012 - 08:13 PM

I think I'll leave that part of servicing a diesel I'll leave to the experts. Good to hear your making headway on the tractor. You'll have to let us know how it turns out.

#30 boostedbuick OFFLINE  

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Posted December 12, 2012 - 09:12 PM

Aww come on it's not rocket science. Shim kit is 30 bucks and if the tips are worn/rusted/damaged I found the kubota part number for an entire new tip with pintle for like 18 bucks each online (without price shopping). Just remember to use a toothpick to clean the tip so you don't mess up the precision machining :).

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