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Old 10-09-2016, 12:48 PM   #1
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Generator 3.5kw Kubota - rebuild or replace

Engine: EU300, single cylinder, horizontal piston.

Initital issue: excessive cranking resulting in salt water entering through exhaust valve.

Time: Prior to boat purchase, engine at 10 hours.

At the time of purchase, a condition of sale was to make the genset operational. PO replaced head, valves, head gasket. Cylinder sleeve and rings were not replaced.

The engine has a single horizontal cylinder. At the time of sale, the genset was disassembled, and I took a look at the cylinder wall. There was some pitting in the wall, along the lowest point, clearly from corrosion. Salt water must have sat in the cylinder for an extended duration. I asked the mechanic if he was to replace the sleeve, piston, rings. His response was, if that much work was required then the entire engine should be replaced.

2.5 years and 350 hours have passed. After the repair the engine would crank for approx 10-12 seconds and turn over. I now need to crank 3-5 times at 12 seconds per.

The case breather hose has exhaust gas and is blowing a small amount of engine oil. My short term fix was to relocate the hose outlet from the drip pan to the air filter intake. That patch covered from 250hrs to 350hrs. Engine is now blowing too much oil, which is accumulating and dripping down the hose into the pan.

Valves checked frequently and to spec. The start battery is dropping faster than engine start.


Is my diagnosis correct?

If I pull the engine, is it worth the effort to replace the sleeve, piston, rings? I'm reasonably confident I can do all the work except for removing and inserting the sleeve.

I've been trolling ebay and online for a used EA300, without success.

EU330 is Kubota's current model, tier 4. Waiting on a quote, but am I naive to assume a new stock EU330 will fit? Strip the stator, fuel tank, radiator, and bolt on my existing heat exchanger, fuel and generator pulley (designed for EE300)?

I'm not to the point of accepting the need for a new genset, and the $6-8k expense. If it comes to that point I think I'll expore a bigger house bank, bigger inverter and a possible solar or wind charge.

We are away from the dock once a month for 2-5 days. Biggest load is refrigeration.


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Old 10-09-2016, 02:09 PM   #2
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City: Essex, Ct
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I think your diagnosis is correct: saltwater corrosion to the cylinder wall and rings has lead to poor compression which is evidenced by crankcase blow by.

PM me your email address and I can send you a parts and service manual for the E300 engine which I downloaded from somewhere as it is the engine in my NextGen 3.5KW genset.

Replacement of the piston, rings and liner looks straightforward with the exception of the liner. The manual shows the use of a liner removal tool. Maybe a specialized machine shop would have that tool. I agree everything else can be done by a shadetree mechanic which sounds like you and me.

But I believe that an E300 block is an E300 block and if you can find a replacement it should fit.


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Old 10-09-2016, 03:08 PM   #3
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Hi David

Thanks for the confirmation. I chatted with my work truck fleet diesel mechanic, he said he can pull and install the sleeve, he's got an assortment of pullers at the shop. All he needs is parts and torque specs, and you have the service manual, so perfect. I'll send you a PM and thank you.
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Old 10-13-2016, 10:35 PM   #4
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Old 10-15-2016, 11:04 AM   #5
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Yep, water got to that thing. It should not have been built back with that. Roughness chewed up the rings.

Is that a steel liner pressed into an aluminum block? Or a steel liner pressed into a cast in steel sleeve? I think the block is al?? Not sure how easy it would be to press out. May need to make a tool on a lathe. Even then, still probably cheaper than replacing block or engine.
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