Yanmar Key position ?

[MrBee]

I'm pretty new to Diesel engines.
A few times while motoring, due to the bad location of the Engine control panel one of us in the cockpit have bumped the key, while the engine was running, and turned it off. When I noticed this I turned it back on and assume that no harm is being done but wanted to know for sure.
thanks
Brian

 

[Guest]

Key

Hi Brian, the key on our boat seems only to activate the engine hour meter and related instruments on the panel. I frequently turn the ignition key off as I approach our slip, a dock or mooring.

Terry Cox

 

[bob12312]

Same thing has happened to me a few times.

Engine and charging system suffered no ill affects. I'll bet all is fine for you also

I now am sure to use a loose key with no other things connected to it (other keys, ring, floatie etc). This reduces the chance of accidentaly knocking it into the off position while the engine is on, which you should never do

 

[Ed Schenck]

If you have a tachometer then turning off the key can be disconcerting. On my boat the engine will seemingly be running fine but with wacky RPMs. And as mentioned the instrument lights will not work.

 

[Allan12210]

Audible alert

Possibly the most important function of the key position is that the audible alert won't sound if it ithe key is turned off. Yes, you can run the engine with no problem with the key off, but if you lose oil pressure, overheat or the alternator takes a dive, you won't be notified audibly. Could be expensive.

 

[bob12312]

As I recall turning key off while diesel engine is running can result in charging

running can result in charging system damage. I'll have to research it again.

 

[txtowman]

it can blow the diodes in the alternator if it is internally regulated.

 

[Allan12210]

Ignition switch is not connnected to the alternator. It brings voltage from the batteries to the various instument panel accessories like lights, buzzers, tachometer. It also allows for voltage through the start button to ground to close the starter motor relay to kick the starter motor. It provides nothing to sustain engine operation as there are no spark plugs, coil, points (i.e., gasoline engine). If the alternator is wired through the battery selector switch, that is where there could be a problem. If the slelector switch is changed while the engine is running, there is risk of blowing the diodes. Some selector switches have protection by running the field circuit across another set of contacts. Those will break first, then the batteries will switch and the field can reconnect without damage.

 

[MrBee]

I do understand about the Battery selector switch, Just wondered about the Key. This is an original install from 1991 motor. I thought it only feeds power to the lights, buzzers and starter so didn't think it was a big deal, EXCEPT as stated that the Warning lights and buzzers would not come on.

Thanks
Brian

PS On my list of projects is to make a box to install in the Cockpit side that will house the Engine control panel and be Recessed with a cover. Some times it hurts the Ankle a little when you step on or bang against the key.

 

[Warren Milberg]

Here is a suggestion to see if you may be putting the diodes in your alternator at risk by turning the ignition key off when the engine is running: With the engine off, put your main selector switch on Battery 1. Turn you cabin lights on. Watching your lights, now switch to Battery 2. If the lights don't flicker when you pass from Batt I to Batt 2, you are probably in safe territory. If they do flicker, you may have the older "make or break" main switch that could damage your alternator by either turning the key off or switching batteries while the engine is running.

 

[fredr]

The ignition "on" position does supply current on these units to the alt field post on the alt.
One way to check a charging system to see where the problem can be, is to be sure that with the key in the "on" position, there is current going to the field connection on the alt. because it is not a one wire self exciting alt.
It normanlly will not hurt anything but I would not continue to push my luck. You are just removing the field current and the alt will stop charging.
As others have said, turning off the battery switch on the other hand can destroy a voltage regulator and or diodes in the alt.

fred

 

[Stu Jackson]

I'll say it again and will continue to repeat it until

you guys get it and start saying it too:

IT ALL DEPENDS ON HOW IT'S WIRED!!!


You need to do some detective work on YOUR boat (not mine, not Warren's not Sam's) YOUR boat, and find out how it's wired.

Your alternator could be wired to your 1-2-B switch, another switching arrangement or directly to your house bank (the preferred way, in which case the switch woudn't affect your alternator).

All MY key switch does is turn the regulator off and on, as well as the engine hour meter which is integral with my tach. I can trun my cockpit key switch off AND I can turn my 1-2-B switch off WITH THE ENGINE RUNNING !!! and my alternator will be just fine. I'll bet you can't, but I don't know for sure.

I DO NOT know how your boat is wired, nor do any of the people on this board. 'Cuz you don't know and if you do haven't told us. Sure, there are 'traditional" wiring methods, but who knows what you or your PO may have done. We don't if you don't.

So before you even think about listening to what they're saying, go find out how your boat is wired, then tell us and then we can help.

Because without that, as kindhearted as they may be, they're only guessing, which isn't very helpful to your diodes if they're wrong.

 

[fredr]

Because Allan and others here are very knowlegeable, I checked the wiring diagram to be sure I did not give miss information. On the 1, 2 and 3 GM Yanmars they use a Hitachi alt. It has a Battery wire the bolts on and an "L" shaped connector with 2 wires, one of wich is the field wire that receives current when the key is in the "ON" position.
BTW a 1986 Nissan Stanza wagon uses the exact same alt except for 2 things. The Nissan alt is a 70 amp, and it takes a slightly different length belt on my 3GM.
Oh yes, the third difference is a reman cost $124 from Napa or Carquest. Mine has lasted 5 years so far.

fred

 

[Stu Jackson]

Huh? The ONLY part of that last post that made any sense or is germane to this discussion is the wiring part. The alternator, it appears is case grounded, meaning it doesn't have a separate ground wire, and the key switch energizes the internal regulator.

Accordingly, turning the key switch off only turns off the regulator and therefore alternator charging.

fredr's earleir comments:

1. It normanlly will not hurt anything but I would not continue to push my luck.
--nonsense, it's either OK or not. What the heck does luck have to do with?
2. You are just removing the field current and the alt will stop charging.
-- that seems right

BUT - stop guessing, and stop listening to us.

GO FIND OUT on YOUR BOAT!

 

[fredr]

I agree Stu, I added a second comment thinking about your very point.
If it is a Hitachi AND has original wiring, the field wire comes from the key switch.
This just turns the alt on and off.
So with the key switch off, using a meter or test light, there should be current on ONE wire on the alt which feeds the battery and it "hot", supposedly, when ever the battery switch is on.
Turning the key switch on should provide current to a SECOND wire.
And, keeping Stu's comments in mind, some systems run the field current wire through a normally open oil pressure switch so if the engine stops running the field current is removed.
I have not seen many one wire self exciting alts but they are out there.
Also, Stu's point regarding the battery switch, I have seen alot of folks turn them on and off with the engine running, and have no damage, and I also witnessed an expensive 3 step regulator get destroyed by doing it.

fred

 

[fredr]

Gee Stu, I am sorry to upset you, I added BTW just for info.
I will let you do all the posting from now on.

My apologies.

fred

 

[RichH]

it can blow the diodes in the alternator if it is internally regulated.

ABSOLUTELY CORRECT. If the key switch doesnt make a 'clean break', and there is any 'electrical noise' from the switching you can most certainly 'fry' the alternators diodes ... and also any 'smart' external regulator if so equipped.

.... and especially if the 'brown' wire is connected to the switch.

 

[Stu Jackson]

Gee Stu, I am sorry to upset you, I added BTW just for info.

I'm not upset, I'm, first, responding to what you wrote, not what you may have had in mind, and second, trying to get Mr Bee to figure out his boat and not listen to "maybe" speculation. That's all.

Write away, fred, but adding stuff later to make your post say something different may not be the way to do it.

 

[MrBee]

I do know i have to figure out how MY boat is wired. I was just trying to get an idea of the possobilities. I do have an older 1-2-both -off switch, and know that it should not be turned off with the engine running. When I get time I will look into the way it is wired, probably over the winter. For now I will try not to let it get turned off by accident. I also know that I have an engine bank, (one Battery) and a house Bank, also one battery.

Brian

 

[Stu Jackson]

Brian, if the whole issue is the crew hitting the key

and since you want to spend winter time checking the wiring, is there a creative way you could cover the key, or maybe have another key copy made and severely reduce the size of the key "head" leaving enough area to turn it so people don't keep hitting it? Hard to tell without a picture. Our key does get in the way and we have to be careful not to hit it when the engine is on. When the engine is off, we take the key out and hang it on the engine stop handle. The original key the PO gave use was so bent.... What worked for us was to put a BIG colorful key float on it, but we still do hit it. Heck, how about squishing a key float onto the head of the key, then they'd hit the float not the key itself. Just brainstorming.