Yanmar Engine revs to 4000 RPM

[sazarac]

Originally Posted by NoTies

I wish people would stop blethering about the prop. IF the engine is in fact developing over 4000rpm in neutral and it's not as faulty tach setting then the engine will be developing more power (until it disintegrates) therefore of course it will rev higher in gear as well. Forget the prop, forget the shaft, forget the reduction, forget everything except having the tach calibration checked in the first instance.

The prop is irrelevant. Until the tach is checked. Then if the tach is correct the governor is malfunctioning.

[mtarcher]

Hi BlueChicago... I am having an issue loading up the PDF given to me (from Mastry) about pulse setting parameters for the B20 panel. Pm and I will email it to you. Otherwise, you might contact Carl Schwimmer at Mastry for the info.
Sandy

[BlueChicago]

Originally Posted by mtarcher

Hi BlueChicago... I am having an issue loading up the PDF given to me (from Mastry) about pulse setting parameters for the B20 panel. Pm and I will email it to you. Otherwise, you might contact Carl Schwimmer at Mastry for the info.
Sandy

Hi Sandy,


I really appreciate the offer. No worries. It appears that the Yanmar Operation Manual that came with the engine has the settings details.


Cheers,


-BC

[jakkum]

Originally Posted by Cpt Pat

As an aside, diesel engine runaway is what caused the initial explosions leading to the Deepwater Horizon disaster. A gas "blowout" caused the platform to be enveloped in methane gas. The diesel AC generators aspirated the gas and used it as fuel. Even with the diesel fuel cutoff by the engine speed regulators, the engines continued to run on the methane without fuel-regulated speed control. In a situation like that, the only way to stop a diesel engine is to cut off its intake air. If you watch the movie, you can see this catastrophic process progressing, but it is never explained. You can view that 1:50 into this clip:

Note: the output voltage from a generator is proportional to its rotational speed. That's why the lights exploded.


I sometimes wonder if vessels have been lost at sea because of either propane leaks reaching the engine, or outgassing of methane from the bottom; leading to "dynamic disassembly" of a running diesel on board. It's too bad the engine shutdown on many diesel-powered boats shuts off the fuel flow instead of the intake air. At least that would give the crew some chance of manually shutting down a runaway diesel engine. This is one case where a gasoline engine can be safer: you can shut it down simply by turning off the ignition.


The Deeepwater Horizon accident was especially inexcusable because the runaway would have been so easy to detect and prevent. Diesel engines driving an AC generator run at one constant RPM, and anything over that value could have activated an intake air cutoff. It's not like methane-aspiration was unforeseeable on an oil platform.


There's more here: https://www.aiche.org/ccps/conferenc...away-explosion

A diesel engine can also run away when the piston rings are a bit worn and there is too much lub oil in the engine. I have had that twice and could stop it by putting it in astern. You will see it is lub oil because it causes an enormous cloud of smoke.
In this case I would advice to try the engine carefully in neutral. If it goes well over 3250, most likely the tachometer is wrong. And if the engine reaches the same speed in forward. . , most likely the overnor is ok.
Anyway, first thing is the tachometer check.

[Viajero]

Most diesel runaways are the result of the engine burning its own lube oil. The best way I’ve found to stop a runaway is to have a Co2 fire extinguisher handy to fire into the air intake.

[jakkum]

Originally Posted by Viajero

Most diesel runaways are the result of the engine burning its own lube oil. The best way I’ve found to stop a runaway is to have a Co2 fire extinguisher handy to fire into the air intake.

you are absolutely right, bit if the engone is downbelow and I am at the helm, putting it on gear is just a bit easier than running for a co2 extinguisher and bring the lump below to see the conrods already sticking out.
On neutral, thongs like that could happen so please put it in gear. Just in, no extra!
Most of the time it will slow down rnough to stop it picking up too much luboil

[Icarus]

Originally Posted by BlueChicago

I purchased a new Gori 2 blade folding propeller this past spring. Along with other necessary specifications, I provided the distributor with my engine model (Yanmar 3JH5E), and transmission (KM35P @ a 2.36 ratio). The distributor indicated the diameter and pitch needed, and I ordered it.

I had never pushed the engine with the new prop until later in the season when heading back for winter haulout. At that point, I noticed that I could push the engine to 4000 RPM (as displayed on the tach).

The engine is relatively new, and currently has about 200 hours on it.

I'm embarrassed to say that I can't remember what the maximum engine speed was when the old prop was still on the boat. I want to say about 3000 at full throttle (I replaced it because the original, pitted, cracked prop would have cost more than half that of a new one - and no guarantees)

Assuming that the tach is accurate, my questions are:

Should I be concerned about revving the engine this high?
Do I have the incorrect prop, or could the issue be related to something else?



Thanks


-BC

Looks to me your prop is the wrong seize. You haven't supplied the prop dimention, makes it hard to give an accurate answer.
There are prop/engine/ tables available so you can look it up yourself.

[Icarus]

Originally Posted by sazarac

The prop is irrelevant. Until the tach is checked. Then if the tach is correct the governor is malfunctioning.

Not quite

[RaymondR]

Not familiar with that model of Yanmar but if it's pre common rail fuel system there is usually an adjustment for rev limiting which has a locking wire which has a lead seal on it. If the locking wire or seal is missing it's possible that someone has been messing about with the max rev setting.

[LargeMarge]

Did I read that right? 4,000rpm? Garsh, that RPM seems high. Can you verify your tachometer is accurate?

Diesel engines are chuggers. Their long-stroke connecting-rods efficiently work in their torque range at far-lower engine speed than you report. Does your operator manual specify your effective engine speed? I imagine it is probably in the neighborhood of 1,200 to 2,200rpm. Lower RPM usually equates to engine longevity; higher RPM can be appropriate for hot-rodders with more money than supervision.

Good grief, spinning four-grand, your GPH must be through the roof!

[Wotname]

Originally Posted by Icarus

Not quite

I really thought all posters had by now accepted that the prop size is irrelevant to the OP's issue

While it is highly likely the OP has a faulty tacho, a faulty governor could also allow for his engine to reach 4,000 rpm.

There is absolutely no way the prop cause be causing the high rpm if the tacho and governor are serviceable (i.e. working as designed).

If you still believe the prop is the issue, please explain how prop selection can override the engine governor.

[Sailmonkey]

Originally Posted by Icarus

Not quite

Oh please do tell.....

[peter57]

Originally Posted by Icarus

Not quite

The Prop at this moment is totally irrelevant to the OP as without the prop even installed a 3JH5 should only rev to 3000rpm or out of gear.

[B4A]

What was the solution to this issue?

[RaymondR]

Originally Posted by Cpt Pat

As an aside, diesel engine runaway is what caused the initial explosions leading to the Deepwater Horizon disaster. A gas "blowout" caused the platform to be enveloped in methane gas. The diesel AC generators aspirated the gas and used it as fuel. Even with the diesel fuel cutoff by the engine speed regulators, the engines continued to run on the methane without fuel-regulated speed control. In a situation like that, the only way to stop a diesel engine is to cut off its intake air. If you watch the movie, you can see this catastrophic process progressing, but it is never explained. You can view that 1:50 into this clip:

Note: the output voltage from a generator is proportional to its rotational speed. That's why the lights exploded.


I sometimes wonder if vessels have been lost at sea because of either propane leaks reaching the engine, or outgassing of methane from the bottom; leading to "dynamic disassembly" of a running diesel on board. It's too bad the engine shutdown on many diesel-powered boats shuts off the fuel flow instead of the intake air. At least that would give the crew some chance of manually shutting down a runaway diesel engine. This is one case where a gasoline engine can be safer: you can shut it down simply by turning off the ignition.


The Deeepwater Horizon accident was especially inexcusable because the runaway would have been so easy to detect and prevent. Diesel engines driving an AC generator run at one constant RPM, and anything over that value could have activated an intake air cutoff. It's not like methane-aspiration was unforeseeable on an oil platform.


There's more here: https://www.aiche.org/ccps/conferenc...away-explosion

Drilling rigs are designed within a set of "zoning" rules which are defined by the possibilities and probabilities of combustible gas/air mixtures being present during drilling operations.

Normally the closer to the source ie. the wellhead the more strict the rules regarding ignition sources are.

Occasionally, usually during pressure control incidents where the systems designed to remove gas have either not been activated or are deficient, the expulsion of gas from the well is of a magnitude where combustible gas/air mixtures can extend beyond the at-risk zones and encounter ignition sources as appears the case in the Deepwater Horizon incident.