Urba Centurion Update - (Kubota diesel, 100+ MPG in mixed driving - Fall 2012 on)

[changzuki]

Originally Posted by redneck

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What, no flame test...



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Page 121 of the Kubota manual:
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Waaayyy tooo good to let slide..:
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~CrazyJerry
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[Xist]

Some things cannot be unseen...

[nemo]

Any updates on the fuel injection problem?

[changzuki]

Originally Posted by nemo

Any updates on the fuel injection problem?

Yes, drafting it now - will post in a bit...
~CrazyJerry

[changzuki]

- Centurion's Heart Murmur....
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In a quest to find out the problem involving a vibration and then a potential link with "air present" at the fuel injector(s), the heart of the fuel system needed to be looked into. Sporting its factory "Diesel Kiki" id tag, and unmolested factory Kubota paint, suggested the injector pump to be "OEM" for the vintage D850.
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Identifying the pump using the ID tag is truly a pain in the behind. There's a pitifully small amount of room to try and get one of those "little mirrors on a stick" into a useful position (between the tag and the cylinder head) to see all the stampings on the tag:
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Removing the pump isn't much of a job but in addition to the lines and linkages, does require the intake manifold to be removed:
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In your hands, the injector pump feels quite solid. To call it an injector pump is almost a misnomer.
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There is actually a "pump" for each of the three injectors. Flipping the pump upside down reveals each pump's roller:
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These rollers raise and lower on their own specific separate camshaft lobes:
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The only thing that separates each pump's fuel from the engine's oil are some very tight/well machined tolerances.
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Initially, this little unit looks bomb-proof but further investigation suggests otherwise....
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There appears to be "flakes of metal" present on the topside of the roller area - and that should not be.
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If these little trouble makers are getting into the injector(s) or any other part of the fuel system, then it may answer many of the previous questions, as well as raising some new ones...
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It may also answer the question of what the next purchase will be!
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~CrazyJerry
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[nemo]

Originally Posted by changzuki

If these little trouble makers are getting into the injector(s) or any other part of the fuel system, then it may answer many of the previous questions, as well as raising some new ones...
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It may also answer the question of what the next purchase will be!
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~CrazyJerry [/B]
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Stay tuned for the thrilling conclusion.


Thanks for the update.

[changzuki]

- Centurion's Heart Surgery....
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Disassembling the little pump is pretty easy but attention to detail is a must! Like the injectors, the pump assembly contains plenty of calibrated parts, so pay acute attention to everything if you plan on reassembling and reusing it.
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A specific example that comes to mind are the fuel timing marks on the control rack.
(One for each pressure plunger / to each injector.)
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If you don't get these right you may be in for a real treat!
The worst case scenario is a "runaway engine" whereby max fuel is being delivered and the governor is having little or likely no affect. Speaking from experience, few things in life give you quite the same adrenaline rush as a runaway diesel!!!
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*TIP* Have a game plan to shut the engine down in the event of a run-a-way. On this little engine the intake is pretty easy to seal if the air filter is off and it'll shut-down pretty quickly. Also, the decompressor will work if nothing else is handy.
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For whatever reason, some of the machined walls inside the pump appear to be deteriorating and a closer look in the area of the above photo reveals some of those thin metal shavings/flakes previously mentioned:
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A thorough cleaning was executed and the pump returned to its rightful place. I suspect possible scoring in the #1 plunger as the vibration was still present. Cracking the line on that injector barely made a difference in rpm drop at idle. At half throttle or more it did seem to smooth out and run halfway decent. A couple of road tests later and no change - just some black smoke here and there.
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Due to the internal pump deterioration and presence of rogue metal distributed within areas of the pump, it was time to see if a replacement unit was available...
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All we should need are the factory numbers from that Diesel-Kiki tag to cross reference it to a new part number. Hopefully there's not a repeat of the injector fiasco or I'll end up with a "couple" of pumps before it's all said and done.
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Hey! What's this already?????
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Did I mention these are really, really, expensive?
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I MEAN - HOLY CRAP!
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Still, I'll gladly take this injector pump misfortune over the following:
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WoW!! Did you see that?
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~CrazyJerry
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[nemo]

Do you have any idea how many hours are on that pump or how old it is?

[nemo]

Originally Posted by changzuki

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Ouch!



Do you have any idea how many hours are on that pump or how old it is?

[changzuki]

Originally Posted by nemo

Do you have any idea how many hours are on that pump or how old it is?

nemo,
This D850 is a "crate engine" purchased in 1982 and total hours on it are less than 150. When dissecting the original injectors and then the pump, there were internal traces of rust pitting here and there (water!) Problems in the pump resulting from that would make sense but the flaking metal from other area where I can't see anything just didn't add up.

Thinking back along the way, all of the little signals of a failing pump were there but because they were intermittent they were ignored.

An internet search of any other Kubotas having this issue turned up zero, so, this is likely a one-shot deal... I hope!

--That house in the pic above is (was) only about a mile from my place. We get these amazing little "microbursts" from time to time in the summer.

~CrazyJerry