Marinizing a Cat C3.3B DIT

[NSboatman]

Hey folks -


I have potential to pick up a nearly new Cat C3.3B, 74hp turbo diesel. Was in a skid steer that got rolled over; and is being written off. It runs fine and has no smoke, good pressure, easy starting etc. Seems like the engine wasn't hurt at all in the incident.


I'm looking at it as a potential replacement for my 40 y/o Perkins 4-154 (65hp); which is running beautifully but can't go forever. Parts for it are becoming a real bugger.


Anyway - I probably wouldn't choose a turbo, I'm more of a low-speed chug-along engine guy - but this kinda fell into my lap and it might be a good option.


What should I look for and research when considering a marinization of this skid steer mill? is it even a reasonable choice?


thanks all-



Question - I know enough about the perkins/kubota/yanmar/Deere engines to make educated guesses, but I know ZERO about Cats. Especially electronically controlled ones like this one (I think it's a 2019 or 2020).

[skipperpete]

The engine you’re looking at is a “Cat” branded Kubota 3307 and it shouldn’t be too hard to marinise it. You need a
1. heat exchanger/exhaust manifold
2.raw water pump
3. Flywheel housing adapter( probably)
4. Drive plate
5. Engine brackets
6. Maybe a shallow oil pan.
Maybe try “Beta” for a manifold, its possible that they did a marine version of this engine.
But the real issue is that skid steers have constant speed governors and drive hydraulic pumps so the engine speed remains constant like a generator regardless of load whereas yachts have variable speed governors. It will work but the throttle behaves a bit differently.
The electronic version might be re programmable back to variable speed, my 4wd has a constant speed governor setting in low range so its definitely a possibility.
You have a lot to do and spend to get this to work so drop off the oil pan and check the internals, it would be depressing to get it into the boat only to find that it had run upside down or had been otherwise damaged in the original incident.
Pete.

[NSboatman]

Thanks Pete- that’s great info. I wasn’t aware that it is actually a kubota. Really good to know. I’ll go and have a chat with the kubota folks and see if it can be programmed back to a variable speed unit. Thanks mate!

Oh- and def agree. Before I spend much I will be checking the bottom end. It was running when It flipped over so it did run oil starved for some period of time. Need to know that there’s no real damage there.

[NSboatman]

Pete- finally back at this after a month away (actually sailing, which was a lovely thing). I’ve finally gotten eyes on this engine now, and as usual, it’s not simple…. It is as you said- a kubota v3307- turbo’d and is a common rail electronic controlled engine. I would have preferred that it was a basic old mechanical injection diesel, but such is life. It also has a giant diesel particulate filter on the back end - which of course I’d get rid of- but there are a couple
Of sensors tied in to this unit that I’d have to deal with. I guess I need to speak with someone who could guide me on the re-programming of the ecu. Our local cat dealer isn’t interested in working woth me on this (not a big surprise) so I’m going to have to dig a bit deeper elsewhere. Any suggestions?

[skipperpete]

I think you’ll have difficulty getting into the walled garden that Caterpillar has around its electronic common rail systems (like MTU, Cummins, Detroit, Deere) but there is a ray of light....... the 4wd and power performance fanatics. These guys are way out in front with remapping, deleting functions and modifying CPU’s and you might even discover that it’s not the Cat electronics package, it could be Denso.
Before doing too much with the electronics you should invest a bit of time in checking out the internals of the engine........the structure of skidsteers is highly repairable so it’s possible this thing was written off by the insurer because they either know or suspect that the engine was damaged by the “run dry” event.
Pete.

[NSboatman]

All very good advice. I doubt though, that it is even cat electronics, since the ecu seems to have a kubota sticker and part no. That said, I’ve now had a couple of good conversations with local mechanics who are both saying don’t touch this engine. For 3 reasons- the roll over and runaway that most likely occurred probably damaged the turbo bearings and possibly the cam bearings as well as the main bearings, and that adds a couple grand to the repair tally; second the reprogramming of the ecu to run reliably in the boat can be done, but bypassing all the dpf functions and existing operating parameters is a hack and may not be stable in the long term- especially when combined with marinizing and the related bits required; and third; while I can certainly get a heat exchanger setup that will duplicate a radiator cooling system, the uncooled exhaust manifold and turbo housings will be very hot inside a confined engine room on a sailboat. I could get blankets for them, and also invest in better airflow in and out of the engine space; but it will be another difficulty in getting a reliable system in place.

…so I’m reconsidering this great deal! Maybe I should just rebuild my 4-154!

[Compass790]

I read this with interest,
Think the local mechanics warning you about the turbo were spot on. AFAIK they are very sensitive to any interruption to oil feed. Know of a couple of people who've knackered their turbos from just not running them down back when the run down wasnt in the ecu.

[skipperpete]

I love the 4-154 and its 3 sisters but they really should have put more thought into the raw water pump

[NSboatman]

I hear you on the water pump. Rebuilt it twice already. Next time I may say screw it entirely and put in an electric pump…