Marinized Kubota Engine . . . What Are the Differences ?

[Snowpetrel]

My Nanni 4.110He is a standard Kubota Vh 1100 block with a heat exchanger and exhaust manifold cooler added, it also has a remote oil cooler adddd to make way for a bigger alternator, and a Impeller pump driven of the cam shaft added. Asside from these, the bellhousing gearbox and engine mounting system its seems to be identical to the kubota base engine. Saying this it would be a bit of work to custom fit all this stuff. The nanni conversion seems like a good one.

For what its worth my last boat had a isuzu 3kr1 industrial motor, it used keel cooling (skeg cooling) and had a dry exhaust and uncooled exhaust manifold. This has to be the simplest way to convert a non marine motor. The dry exhaust is hader to live with than a wet exhaust, but the keel cooling was very nice.

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[colemj]

Originally Posted by brownoarsman

I was told, but can't confirm, that universal's marinization of kubota blocks was limited to the wet exhaust manifold, the water pump (jobbed out to Sherwood), and the freeze plugs.

What more would you expect in a marinization (I assume you are including a heat exchanger in the manifold)?

Mark

[brownoarsman]

Originally Posted by colemj

What more would you expect in a marinization (I assume you are including a heat exchanger in the manifold)?



Mark

Well, not for mine (RWC rather than FWC) but for the others in the portfolio, yes. I've also heard that some marinizations involve teardowns of the engine and replacements of bolts and other parts with bronze components. But I have no idea about that.


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[a64pilot]

What would be the difference in freeze plugs?


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[brownoarsman]

I think the factory ones are thin mild steel, and subject to corrosion that will then cause a leak in the cooling system. Replacing them with corrosion-resistant plugs eliminates this weakness. Again - can't confirm, just what I was told by a fellow who suggested I just swap the marinized parts on my Universal 5411 to a used Z500 Kubota engine rather than mess around with trying to get the head off.

[Jim Cate]

I've also heard that some marinizations involve teardowns of the engine and replacements of bolts and other parts with bronze components.

I've never seen nor even heard of such a conversion. Sounds like internet talk to me!

Jim

[RaymondR]

I marinized a Kubuto V2203 about five years ago.

I started off with a heat exchanger/water cooled manifold and abandoned it for raw water cooling.

I knocked all the freeze plugs out of the block in order to install threaded inserts into which to screw anodes.

During a hull refit in 2013 I installed keel cooling tubes and am in the process of converting to keel cooling at the moment.

I bought the engine new having a bit of mad money at the time however if I was doing it again in normal circumstances would use a Japanese auto diesel engine instead of the Kubuto. These things run forever and parts are very cheap.

The V2203 is giving good service but being a long stroke, low reving engine tends to be a bit noisy and puts a lot of vibration into the hull when idling.

[Cottontop]

Originally Posted by colemj

What more would you expect in a marinization (I assume you are including a heat exchanger in the manifold)?

Mark

Link to a John Deere guy talking about what needs to be done.

Diesel Marinization - what it takes

[jimbunyard]

Originally Posted by Cottontop

Link to a John Deere guy talking about what needs to be done.

Diesel Marinization - what it takes

Interesting article. Probably the most salient point (for most on this forum) is saved for last:

"The best marine engines utilize heavy-duty industrial base engines, typically used in agriculture and construction industries. These engines all have replaceable wet liners and very robust construction that allows very long life (typically 40,000+ hours) and economical rebuilds - this is vitally important to commercial customers who will accumulate over 8000 hours per year of running time if their application runs 24/7. <That type of construction is completely unimportant and needlessly expensive in a pleasure boat application that is lucky to run over 200 hours a year.>" (my italics)

[Cottontop]

Originally Posted by jimbunyard

Interesting article. Probably the most salient point (for most on this forum) is saved for last:

"The best marine engines utilize heavy-duty industrial base engines, typically used in agriculture and construction industries. These engines all have replaceable wet liners and very robust construction that allows very long life (typically 40,000+ hours) and economical rebuilds - this is vitally important to commercial customers who will accumulate over 8000 hours per year of running time if their application runs 24/7. <That type of construction is completely unimportant and needlessly expensive in a pleasure boat application that is lucky to run over 200 hours a year.>" (my italics)

He talks about modifications to electrical components, also.

[brownoarsman]

Originally Posted by Jim Cate

I've never seen nor even heard of such a conversion. Sounds like internet talk to me!

Jim

I think you're probably right, Jim. Though I'm pretty sure I read it on CF, so it must be true!

Here's a result of a quick google search that discusses some additional marinization detail: http://www.boatdesign.net/forums/diy...ation-650.html
Apparently, sometimes the head gasket is changed on automobile conversions too, not sure how that applies to tractor diesels. Once I get my engine out, I plan to replace the head gasket with the kubota stock one, so I'll let you know how it works out in about thirty years when it fails again!


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[Jim Cate]

I can see that if one was going to raw water cooling, a steel shim type head gasket might have corrosion issues. If one plans FWC, the coolant that the gasket is exposed to is the same as in the automotive application, so there should be no problem.

Jim

[brownoarsman]

That makes sense, Jim. Thanks for the knowledge-and just more reasons I'm kicking myself for buying a boat with a raw water cooled engine!


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[RaymondR]

Steel and cast iron are both in the -0.60 to -0.71 Volt range in the galvanic series so it appears that there should not be much of a corrosion potential with steel foil type head gaskets. I seem to recall the old Yanmar had a copper foil type gasket and copper is -0.30 to -0.57 Volt which is more of a potential difference and I did not have any problem with it.

The biggest problem I had was removing the alloy timing case cover from the raw water path through the engine. I used an interference fit nylon bushing expanded in the cast iron block to do this but I don't know how long this will last before it starts leaking.

I was going to replace the original water pump housing when I convert to keel cooling but am now considering leaving the existing arrangement and fitting another small impeller pump onto the female threaded input shaft on the back of the gear box to supply raw water for the exhaust system.

The alternative is go to a dry exhaust system which removes another source of possible sea water leakage in the steel boat and completely removes the exhaust manifold engine back flooding hazard.

If I've pressed the right keys the two images show the front of the engine and the home made water cooled exhaust manifold.

I used cupro nickel tube and fittings and silver soldered all the piping because I don't like hoses running everywhere. I used t's instead of elbows and the plugs on the t's are anodes.

The water cooled manifold is manufactured from a piece of 2" x 2" steel SHS with SS sleeves for the manifold bolts and a piece of 3" x 2" SS RHS sleeved over the 2" x 2" black steel exhaust tube. The whole thing was manufactured with hand tools and a drill press on the boat.

I'll dig about and see if I can find some photos of the aborted manifold as they show the fabricated bell housing with the dual starter motor arrangement.

To answer the original enquiry, not only can you turn pretty well any engine into a marine engine, you can do it on the boat with a few hand and portable power tools. The result may not look as tidy as the shop version but there is a good chance it will work and the most enjoyable and satisfying boating is that which includes lots of your own inputs.

Ah decisions, decisions, decisions.

[RaymondR]

Foundem, the three images show:

the bare engine stripped of the bell housing before I started the conversion,

a port side view showing the abandoned water cooled manifold/heat exchanger, and

the starboard side view showing the second starter motor.

The bell housing was fabricated from 10mm alloy plate with alloy sleeves thru bolted. This was then enclosed by welding flat bar in between the alloy sleeves.