Kubota Power??

[GILow]

If it helps reassure the OP, I am currently in the middle of pulling out my old Nissan and fitting a marinised Kubota (Beta marine) because anyone I have met with a Kubota is extremely happy with them.

[JPA Cate]

Our heat exchanger failed last year (or maybe the year before that). Jim spotted it when he saw green coolant come out the exhaust. It is a 43 hp Nanni marinized Kubota. The engine has been in the boat for 30 yrs., this year. We are satisfied with the engine. The PO did not keep records, but we have put 5,339 hrs. on it so far, since Jim installed the engine hours meter. It has been quite reliable. However, Jim is scrupulous about doing the oil changes at (or before) the recommended intervals.

Ann

[GILow]

Sheesh! 30 years... is that all?

They just don’t make ‘em like they used to.

[JPA Cate]

Tempus fugit. (Time flies.)

[GILow]

Originally Posted by JPA Cate

Tempus fugit. (Time flies.)

Tempus fugit when you’re having fun.

[n5ama]

I really appreciate the help on the Kubota. It seems the engine is not the issue but making sure the cooling is properly done with a heat ex-changer that keeps glycol on the engine side and seawater on the other with enough capacity to insure cooling. It seems that 18gpm with a 2.5-3" hose and +- 1' length should do the job. I'll either have to find a pto on the engine or a battery powered pump to move the seawater through the heat ex-changer.

[capn_billl]

I have a Kubota generator, runs like a clock. I'm very happy.

[RaymondR]

Tractor engines usually have a heavier block and bell housing than auto or industrial engines because they don't have a chassis. With most tractors the front wheels are attached to the engine block in the front and the transmission and rear wheels to the bell housing. Consequently the blocks and bell housings need to be much stronger. Generally most of the other bits are common to the three types of engines.

I marinized a Kubota V2203 in 2010-11 and sea water cooled it. The three things I had to do were: Design and build an expanding spigot arrangement to pass the sea water through the alloy timing cover. Replace the alloy thermostat holder and hot water discharge fitting with one fabricated from brass. and, Remove the welsh plugs and install brass bushes in the block to take four anti corrosion anodes.

Many of the commercial conversions use a cast alloy combination exhaust water jacket/heat exchanger housing which one should be careful to only ever use the correct anti corrosive cooling fluid in - they are usually glycol based. Failure to do so and use fresh water will ultimately result in corrosion due to the alloy being anodic to the cast iron in the engine. These are usually industrial engine conversions.

Many early auto engine, and one would assume tractor engine, conversions were accomplished using entirely separate heat exchangers with the coolant circulation system on the engine itself largely untouched. Since a radiator incorporated header tank was no longer available a separate header tank was usually mounted on an adjacent bulkhead. A belt driven or electric sea water pump is generally required for these installations.

If you can post some images we can better advise (or mislead) you.

[jimbunyard]

Originally Posted by n5ama

I agree totally. I can visit the boat. The Kubota issue was just one of the things I wanted to research. I am considering purchase but have to get several issues answered before going forward.

I plan to have the standing rigging replaced and possibly the chain plates etc if needed.

Are there retro fit heat exchangers available? If so, who might have them? I'm assuming the same thru hulls that are currently being used on the Kubota could be used for a heat exchanger...

Tom

Originally Posted by n5ama

I really appreciate the help on the Kubota. It seems the engine is not the issue but making sure the cooling is properly done with a heat ex-changer that keeps glycol on the engine side and seawater on the other with enough capacity to insure cooling. It seems that 18gpm with a 2.5-3" hose and +- 1' length should do the job. I'll either have to find a pto on the engine or a battery powered pump to move the seawater through the heat ex-changer.

If needed, aftermarket heat exchangers are available in a plethora of configurations.

Almost certainly the same thru-hulls for raw water and engine exhaust can be used for any updating or changing of the existing cooling system, but perhaps it might be prudent to identify what you have before planning for changes.

There is an about equal chance that the existing system is adequate, or could be made adequate with minor changes.


The 'tractor engine' term is being thrown around alot, and may be as source of confusion as well as being inaccurate.

A more informative appellation might be an 'agricultural implement or small generator engine', as, for a 28' boat, a 2 or 3 cylinder, 12-20 hp diesel is what is likely to have been installed, and while big heavy tractor engines that were, and in some instances still are, a major supporting part of the drive train, design and engineering advances, as well as economic 'necessities', have made it more likely, especially in smaller hp applications, for a modular construction approach. It is, after all, how Kubota and others can use the same basic engine in a lawn mower, a generator, a sailboat, a mini-excavator, a reefer, or yes, a tractor.

Unless something is rather out-of-the-ordinary, for a small sailboat diesel, the sea water supply would typically be through a 1/2 - 3/4" hose, with a maximum flow rate of about 2-3 gpm, exhausting through a 1.5 - 2" exhaust hose and water-lift muffler. On small Kubotas, the PTO is usually on the front of the engine, gear driven and in ag applications drives a hydraulic pump. Life as a seawater pump drive is easy street...

And Kubota engines are generally top-of-the-line in all respects, though, as with most manufacturers, ancillary systems can be a little less reliable... for those manufacturers in second-tier markets, like marinizers or lawnmower makers, this can be doubly problematic.

I've got a 2 cylinder from the mid 60's and a 4 cylinder turbo from the mid 00's, and after (mostly) working the ancillary's (of course) bugs out (electrical and hydraulic), they're both trouble free; very good machines indeed.