Can you hand-crank a Yanmar 15 hp?

[apogee1mars]

Originally Posted by Chris12345

I have often read that advice, but doubt that it really is a good idea: A small diesel cooling water pump pumps next to nothing, but this setup is a surefire way of clogging the pump with debris and loosing the engine when you are already dealing with water in the boat.

You sound like you know what your talking about. "Surefire way" is it? Hmmm. I guess all those commercial guys out on the water for months at at a time should have read the book. So just how many GPM does a small diesel pump?
How many GPM is worthless discharge in the advent of a breach. Have you ever pulled a hatch and observed the crystal clear seawater filling the hull, watching your batteries go under as your auxiliary power is partially submerged? I am guessing not. I hope it never happens to anybody, but unfortunately it does happen.

[fryewe]

My Yanmar 2QM15 came with a great hand crank, obviously homemade, but well designed. I decided to try it, put the crank on the end of the camshaft where the T for the crank fits, and gave her a turn. She turned over but didn't start. I decided to give it a second turnover, and gave it a rip. Didn't keep the shaft of the crank in line with the cam shaft, and I neatly snapped off the end of the crankshaft. It snapped right where the pin went through the hole in the shaft to form the T. Been like that for 28 years now. Haven't had the need to manually start it. Wish I hadn't tested it. If I still had a T on my camshaft, I would use a battery pack as described earlier in this thread.

By the way, don't use a socket on an engine fitting to try to start it. That's a sure way to break an arm. A proper starting crank is slotted so that the the end fitting releases from the engine as the engine's speed exceeds the handcrank speed.

[Chris12345]

We are not talking about a small diesel pump. A small diesel pump does thousands of gallons per hour.

It is the COOLING water pump of a small diesel, the one that is responsible for the splosh-splosh-splosh sound of the exhaust. I would guess a quarter cup per splosh, below 200 gph. Maybe a bit more at higher revs, but still lame compared to ONE $20 bilge pump, which does 500gph. If you want to be more scientific than splosh math, just look at the hose diameters. Hose barb inner diameter, to be precise. The result is the same.

However, the main point is no that the cooling pump is a Mickey Mouse pump, but that it is important: With the setup you recommend, one is likely to loose the engine at the worst time, i.e. when there is water in the boat, because all kinds o stuff will be floating around to clog the pump. And that I know, surefire, from experience.
Not from sinking a boat, just from thoroughly hosing the inside of one down with a garden hose:
The "seawater filling the hull" is not "crystal clear", because it brings up whatever it finds under the floor boards and behind the inner liner of the floor. (Which was the reason for the hosing)

LONG before "your batteries go under" you have hundreds of gallons of water in the boat, by the time "your auxiliary power is partially submerged" we are talking thousands of gallons. These numbers I know, surefire, from simple calculations. Floor area times height of battery top is a good enough approximation, if you care to check that.
I you need to "pull a hatch" to notice THAT much water in the boat, uh-oh.

In that situation, yes, the few gph from the cooling water pump are worthless. But loosing the engine, and thus power to run your electric pumps, just because the cooling water pump chews up an old napkin, a few Cheetos, and one pea, would be a major bummer, wouldn't it?

Oh, and your "commercial guys out on the water for months at at a time " don't hang out there on 27 foot sailboats with 13hp diesels. Their cooling water pumps probably won't die when fed a napkin.

Btw., I wonder what they are doing out there that long? Lighthouse wardens? A container ship goes around the world once or twice in that kind of time.

But still, nice rhetoric.

Originally Posted by apogee1mars

You sound like you know what your talking about. "Surefire way" is it? Hmmm. I guess all those commercial guys out on the water for months at at a time should have read the book. So just how many GPM does a small diesel pump?
How many GPM is worthless discharge in the advent of a breach. Have you ever pulled a hatch and observed the crystal clear seawater filling the hull, watching your batteries go under as your auxiliary power is partially submerged? I am guessing not. I hope it never happens to anybody, but unfortunately it does happen.

[CrazyRu]

I tried to hand crank my yanmar 2qm15. The dumb thing has very small flywheel. It is not possible to build up enough inertia to crank it through the compression cycle when decompression lever released. On another side, we hand cranked friend's volvo engine successfully, not sure about model, the one with huge flywheel up front.
And engine's water pump is useless as bilge pump, as Chris already said. And I know it from personal experience with crystal clear water and rest of the rhetoric.

[INMA]

Hand cranking any engine is a skill best explained in person by an experienced operator.

The Yanmars that I have seen had a chain drive high on the front of the engine to allow the operator to stay high and clear of things. As mentioned the crank handle has a drive set with the back relieved so that when the engine starts the handle automatically disengages. I suspect the Yanmar with the chain had a sprag clutch to avoid the engine driving the crank handle.

I have not used a crank handle on a small diesel, I have seen 100 HP Gardner diesels started when I was a lad and have started stationary diesels with cranks (not sure of the power). Lanz Buldog tractors had an efficient manual starting system where the operator rocked the engine backwards and forwards till they could get it over top dead centre where it would start.

The best advise I can give to anyone manually cranking an engine is to keep your thumb on the same side of the handle as your fingers so that a handle flying won't damage your thumb. Never let your face go near the path of the handle.

Don't fight a crank handle, be smooth and avoid shock loads because it will only hurt your hand, arm and shoulder.

Like kick starting a motorbike or pull starting a chainsaw, the skill is in doing smoothly and getting as much speed as possible at top dead centre.

Decompressors are best let off while some of the pressure is out of the compression stroke so the person cranking does not have to push against full pressure, on the next rotation the inertia helps and with luck a cylinder will ignite.