Neutral Safety switch

D

drfeno

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Jun 19, 2008
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30284
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I have a 1981 Silverton 31c which is in generally good shape. I got out for the first time this season, and my Port motor was giving me issues starting. If I play with the port transmission lever, it changes the behavior, so I assume its something with the neutral switch. The other Odd behavior was that when I did get the port engine started, and I went to start the starboard motor, the port engine stalled. I then restarted the port engine. It also happened once in reverse, where the starboard engine was running and attempting to start the port engine stalled the starboard engine.

The first thing I'll look at is of course the switch, and double check and clean all connections and grounds, check battery voltage.

My starting batteries are in parallel with each other, I'm not sure if this is standard for 2 motors or not, but I guess its possible that if one of the batteries is bad, it could be dragging down the good one.

I didn't have time to look at it in detail this past weekend, but I'm trying to research the best way to troubleshoot it when I can.

Thanks, Dave
 
Your engine are electrically connected together , that bad
each engine must have its own battery system They are never combined except in an emergency to get an engine started
2 engines, 1 or 2 batteries EACH, 2 battery switches
 
What do you mean by ‘giving me issues starting” ? If it’s not cranking at all, and not even a click, when you hit the switch/turn the key - you can look at the neutral safety switch - else it’s some other issue.

How many total batteries do you have? Just these two, or a third “house” battery? Wiring in parallel is not a great practice, but if you have three batteries, only two chargers ( alternators) it’s one way to get it done.
 
Thanks for the replies,

The port engine does crank, eventually, while I play with the transmission lever. It started last week, when I went to start the engine, and upon turning the key, it cranked for a second and quit. I played with the lever a little, and it affected the way it cranked. I typically make sure the lever is in the neutral detent before attempting to start it. That's why I think its got something to do with the switch.

As far as the electrical hook up, Its been set up this way since I bought it in 2008. I'm not saying that its OK, just that its been fine. I'll probably look into separating the starting batteries.

I have 3 banks of batteries, 2 starting batteries in parallel with each other make up 1 bank. The house bank is 1 battery, and I also have a forward battery that runs the windlass and bow thruster. each bank is separated by a VSR that only provides charging current when the voltage is above 13.5 or so. This happens when the boat is running (alternators), or on shore power. I have a battery charger that is connected to only the starting batteries, and they are connected to the other 2 banks by the VSR's for charging only.

I'm going down this weekend to look at it. my plan is to locate the neutral switch on the port engine and temporarily jumper it out. If the issue goes away, then its somehow the switch. If it persists, I'll keep looking. Either way, I'll recheck and clean all connections and make sure I didn't hook something up wrong. I take my batteries home with me each winter and reinstall them in the spring.

Thanks, Dave
 
You are on the right track, I was going to suggest bypassing the safety switch. Or just swap switches, and if other motor now has the problem, you know what you need to replace.

Hopefully you have the switches that are on the transmission, and not part of the shifter control? Much easier if they are.

There is no right way to design this - as long as all batteries have a way to charge, ideally one that isolates them from the rest while charging, it depends how you use your power, if you have a generator, etc. while there is no “right” way, plenty of wrong ways.

I had a boat that was wired with two starting batteries in parallel, with on/off switches for each motor. Both alternators fed back to the same bank - which makes no sense and prevented the batteries from ever getting a good charge when underway. Would have been better to only run one alternator probably.

And the battery to start the generator, and run the house, only would charge when the gen was running, or on the shore power charger was hot. Previous owner had it that way for 20 years, and swore he never had a problem. But he was in the marina every night plugged in, so I suppose it was fine for him.

I find it best to have each motor starting from its own battery, with the alternator charging that battery. But it’s not usually done that way. If you anchor out a lot, and draw down your house batteries, having both motors start from one bank, with the alternator of one motor dedicated to the charging of the house bank makes sense too.

How old are your batteries? They don’t last forever, even the good ones, especially the cheap ones.
 
The starting batteries are probably 2-3 years old. I have a load tester, and I test each battery each year before putting them back in the boat. All the batteries passed this year, they had resting voltage of about 12.65 volts even when I began to look at them this spring.

My thoughts were always that having the motors start while you are out is quite important, so I figured, having the power of 2 batteries doing the starting would give me double the chance of getting started. Also, once one motor was running, the starting bank was being charged, and you would then have that much more power to start the 2nd motor. Electricity is a funny thing, and it may not work that way at all.

most of our boating involves anchoring out, whether its for an afternoon, or 2 or 3 overnights. I don't have a built in generator, but I do have a Honda eu2000 that I use to make hot water and charge the batteries if we're out for more than a couple of days.

Thanks,

Dave
 
That’s one way to look at it, when both motors are connected, having motor 1 running provides amperage to help start motor 2. But by the same token, when you start cranking motor 2, you risk stealing amps from motor 1. I also was concerned about having two alternators feeding back to one power source. I could be wrong, but my thinking was that they would fool,each other into thinking the batteries were charged, when in reality they were not. That’s why I redid my boat, to separate the starting batteries and alternators. But if yours has been working for you for past 12 years, hard to advise changing anything,

Although the version I have is a little older, I consider this book the Bible for marine electrical starting/ charging systems . https://www.amazon.com/Boatowners-Mechanical-Electrical-Manual-4/dp/0071790330/ref=dp_ob_title_bk
 
Thanks,

Since it never has seemed to be a problem, I never really thought about it much, but I probably will look into separating the motors electrically. Doing some research since this happened, it seems like the thing to do. I'll investigate the starting issue, and then look into mapping out to separate the starting batteries.

Another issue I've had has been that one motor uses more fuel than the other motor, They each pull from a separate tank, so its obvious when we get gas. I wonder if due to them being connected electrically, one alternator is taking all the load and creating more parasitic drag on that motor causing it to use more fuel. We'll see. Thanks for all the info.

Dave
 
A quick thought about different fuel flow rates:

One HP is ( roughly ) 750 watts. So, yes, if the alternators were producing different quantities od power, you would have different loads on the engine. But, even at oh, say, 3kw ( BIG load ) you are still "only" demanding 4 HP from your engine.

A bigger suspect in different fuel demand would be slight mismatches in the two props and/or transmissions. Which can account for far more than the 4HP ( or less ) caused bu uneven alternator demand. Even a slight mismatch will result in a one percent difference. In fact I would expect such a mismatch. Most dual prop systems have such a mismatch, and while it is "parasitic", most folks don't even motice fairly large differences.

Of course you could be right, but my money is on prop differences.
 
Dave- My boat has 2 LH & RH MPI gas I/B's with 2 100 gal independent/dedicated tanks, and it has an active RPM Accusync system I use most all the time other than when slow maneuvering. The props are scanned each winter to ensure they are to ISO 1 spec and matched. As a result , usually when I refill the 2 tanks take within about 1-2, gallons of each other, sometimes even closer match.

At the beginning of the season or if I have had work done on the boat and subsequently notice a definitely discrepancy in the gallons each tank will take to fill, the 1st thing I check is the crossover valve between tanks. I always leave it closed but others tend to open it and that always causes uneven usage on my boat.

If your boat tanks have that crossover , is it by any chance open ?
 
Thanks all,

Yeah, I also have my doubts about that much parasitic drag from an alternator. Its probably a prop issue. I've never had the props looked at in detail, and its too late for that this season. Of course I could have it hauled, but its not enough of an issue that it can't wait until fall.

I do have a crossover line between the tanks, but it is closed. 2 seasons ago I had to use it when I had a clogged anti-siphon valve on one tank while underway. That season I was leaving it open in case I had a similar issue on the other tank. Last season it was closed, and has remained closed since then.

Just curious, how much does it cost to have your props scanned and fixed if necessary? I know it can and will vary, I'm just looking for an order of magnitude. My props are 3 blade, I believe 19" bronze on a 31 foot vessel.

Thanks,

Dave
 
What motors? Jumping the neutral start safety switch (ie, CLOSING the circuit) should prevent the motors from starting in most applications. If this is a Merc A or B setup you’re looking for a micro switch on or near the shift plate that’s normally open when it’s in neutral. They do go bad, but this would be a good time to check two potential contributing factors - shift cable adjustment, and load test those batteries. If they’re showing 13 some odd volts at capacity, that’s no bueno. Should be getting 14.4VDC topped up, but even that doesn’t mean the battery is still “good”. Put it on a load tester and draw at least 150 amps and see what the needle does. A little flick to 14. , 13.5 and holding is nothing to lose sleep over, but if it keeps dropping, then get new batteries.

If jiggling the handle does it, I’d start with the neutral switch too, but make sure that it is the switch and not a cable misadjustment or loose shift plate hardware. The lever between the roller and switch body has a real short throw. Leave it to you whether or not you want to “adjust” that thin and easy to bend lever.
 
The Motors are Chrysler 318's in a 1981 boat. The transmissions are Borg Warner Velvet drives attached to Walter V-drives. The Neutral safety switch "closes" (allows current) when the transmissions are in neutral, and opens (no current) when they are in fwd or reverse. I only know from testing. I unhooked the wires going to the switch, and the starter was essentially disconnected (no response to turning the key). when I connected the 2 wires to each other (jumping out the suspect switch), the starter again worked.

This issue has led me to re-evaluate the wiring of the batteries on the vessel, and I'm in the process of separating the 2 motors from a common starting bank of batteries. I did find out this past weekend that my starboard alternator was dead. How long I'm not sure. I'm getting 2 new ones as they are pretty inexpensive ($70 or so).

I do load test my batteries each season when I'm preparing to re-install them. They did pass, at least on the load tester I have. I have to disagree on the battery voltage though, A fully charged resting 12 volt battery should be at about 12.7 volts. anything higher, and the battery is being charged by something, be it a battery charger or the alternators. If you just disconnect a charger, it may have a float charge of more than 12.7 for a while, but it will eventually settle back down.

Dave
 
quote:
Originally posted by drfeno

The Motors are Chrysler 318's in a 1981 boat. The transmissions are Borg Warner Velvet drives attached to Walter V-drives. The Neutral safety switch "closes" (allows current) when the transmissions are in neutral, and opens (no current) when they are in fwd or reverse. I only know from testing. I unhooked the wires going to the switch, and the starter was essentially disconnected (no response to turning the key). when I connected the 2 wires to each other (jumping out the suspect switch), the starter again worked.

This issue has led me to re-evaluate the wiring of the batteries on the vessel, and I'm in the process of separating the 2 motors from a common starting bank of batteries. I did find out this past weekend that my starboard alternator was dead. How long I'm not sure. I'm getting 2 new ones as they are pretty inexpensive ($70 or so).

I do load test my batteries each season when I'm preparing to re-install them. They did pass, at least on the load tester I have. I have to disagree on the battery voltage though, A fully charged resting 12 volt battery should be at about 12.7 volts. anything higher, and the battery is being charged by something, be it a battery charger or the alternators. If you just disconnect a charger, it may have a float charge of more than 12.7 for a while, but it will eventually settle back down.

Dave

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Good call on load testing the batts each season. It’s always surprising how many odd problems a weak battery or poor connections can cause. Ran into it myself with my little Yamaha F40BTLR this season. My go to is an el cheapo Harbor Freight 150 amp carbon pile tester (yes, Harbor Freight - don’t care so much what it reads, just that it reads steady). Catches fire again and/or drop it from a boat on stands, I’m not worried about it.

Velvet drives are generally pretty solid - I have enough experience with 73C’s I can pin down which back pains I still have from lugging them out of engine rooms on 44’s. We usually didn’t use the neutral start switches, but on the hulls that we did they weren’t known for failing suddenly. Check the actual resistance, not just continuity. While you’re right there, if your gears are anything like the 73’s, squirt some oil on the detent ball under the shift arm. Swipe a little dab off the dipstick and swipe it back there. That little spring and ball will appreciate it.

Making me nostalgic for my old boats! Couple alpine green Detroit’s and Velvet 73’s. Lose topside control and my Engineer could sit between a pair of screaming Jimmies and control the governors by hand (and go deaf doing it). Had one of those 6V-53’s run away at the dock once - terrifying experience when that much iron is trying to grenade.
 
Thanks everyone for all the good information.

It looks like the issue with my neutral switch led me to re-evaluate how the batteries and charging system was configured, and it resulted in an overall improvement. First of all, I discovered one of my alternators was not functioning, and one alternator was doing all the work. I'm not sure how long its been like that. I replaced the malfunctioning unit.

So now that the motors are no longer electrically connected, they certainly run better. I'm on the CT river, and this weekend we took a cruise from Chester down to Essex for the day. Its like a different boat. The throttles run at basically the same position for a given RPM, and it is WAY smoother. It seems faster too, but that may be an illusion due to running higher RPM with less vibration.

Time will tell if the fuel imbalance had anything to do with the battery/charging configuration. I will inquire about having my props scanned next off season and do it if its not crazy expensive.

Thanks,

Dave
 
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