Steering pumps

I would hope, as most hang on devices, that the hang-on (PTO) devices back seal would leak out a weep hole and not into the engine.
Gear driven water pumps, fuel pumps and stabilizer hydraulic pumps that I have dealt with are built this way.
Now, this may not say much dealing with old Detroit and Cummins equipment. But worth a double check.
My hang-on Tu-Flo air compressor uses engine oil so it does return its excess oil back into the engine.

Ouch. I can understand your concern.

I do like your electric conversion ideas.
Are there any electric pumps already available instead of a fab'd assembly?

Oh, I remember a hydraulic pump mounted on the backside of a belt driven alternator.
Could be a thought here.

My old 12v92’s had direct drive steering pumps on each engine. When I repowered I was looking for ways to reduce hoses and clutter but I still wanted power steering when running on only one engine, regardless of which engine. I found the SeaStar 24v HPU steering system with integral autopilot pump. I don’t know this is an option for you or not?

https://www.seatechmarineproducts.com/seastar-dc2000-dc-power-steering-unit-24v-autopilot-motor.html

I had this exact thing happen. We kept losing steering fluid. I thought it was the coolers and they looked a little crusty so changed them. It ended up being the engine driven steering pump which did in fact lose probably 1.5 quarts into the motor. It did no damage. It was a C18. In all honesty, a quart or so of hydraulic fluid diluted into 20+ gallons of motor oil isn't going to do a **** thing to the motor.

In the very unlikely event the power steering pump leaks, you'll know where the fluid is going long before you lose 7 gallons in an engine.

Well, better into your engines rather than mine, anyway!

@Pascal: couldn't you connect the pumps to the g/box PTOs instead? Or are they already used for something else?
I like the idea of powering them with electrical motors, anyhow.
Should also allow a better control of rotation speed, btw.

Can your MTU guys reflect on how many times it has really happened? Do your MTU techs have access to the MTU support cloud that could also keeps these stats?
Maybe the big MTU support cloud has an option in the works.
I can see a intermediate adapter that could offer an external weep hole an seal off the engine? Maybe a whole other pump.
Going to electric motors still sound cool but the rework with new hoses and a location to mount the new assembly ads to the challenge (expense).

Knot knowing the agreement you have with the owners and da check book, When these issues came up for our managed boats, I would gather all info and let the owners make the final decision.
The first question asked back by the owners was; What is the factory config and why do you differ from them??
I'm on your side with these concerns but you have commented twice,, Maybe I m just overthinking this. Maybe we are..

Oh, Like my piggy back idea behind a belt driven alternator, Some Trac stabilizer pumps behind the clutch, offers a piggy back for an extra PTO.
Or, Can your stabilizer pump offer some fluid pressure to the steering system?

I read that also, dual gen-sets and the mechanic (engineer) could not transfer over quick enough.
The NTSB also blamed poor maintenance on that failed gen-set a couple thousand hours earlier. Go Figure.
Never been on a 15000HP push Tug. Never knew their steering relied on 3 phase electric pump motors.
I would question that design but for what I know, it probably is how it is done,, period...

And you want to go dual voltage electric?

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All considered, maybe you are indeed overthinking it, but considering that those puppies are worth enough money to buy a nice boat, I'd rather overthink than ignore the possibility.

Also because, when engine dealers (be them MTU, Cat, MAN... whatever), tell you that they never saw a particular failure, but they also recognize it is possible, more often than not it means that they actually DID see it happen, and were instructed by the HQs to never mention it...