What is this part on my 1957 35hp

[wildmaninal]

I haven't been able to figure this part (that is pictured) out, or what function it does. Reason I was concerned about it is because there wasn't any hose hooked to it and I ran the motor without it hooked because I forgot to hook it up. The only reason I know where the hose hooked to is because I have a parts motor that still has it hooked up. I figure it is a pump or regulator but what kind. I haven't tested this part, wouldn't know where to start.

Would this cause my motor not to run at the full throttle?

 

[1946Zephyr]

Re: What is this part on my 1957 35hp

That is a kill switch, designed to kill the spark on one of your cyclinders, to prevent a runaway condition. Typically, they're wired to number 1 point set.

A runaway condition usually occures if the engine is over reved without any load. This usually will happen if your shear pin on your prop should suddenly give away or you happen to give it too much throttle while in a docked position. Typically, the Armeture Plate will have safety stops, set for each gear to allow the engine to be reved only so high. Each step is cut a certain dept to allow the engine to go up to a certain rpms, in each gear. As you'll see on forward gear, the stopping plate, will allow the throttle to go into the full open position.
Unfortunately, those don't work all the time and occasionally over reving is possible, while sitting in neutral position. So, the bigger motors, typically 25 hp and bigger will have those. I don't recall seeing them on the 18's, but it doesn't mean they won't be present there.

Sometimes though, if you experience loss of spark on one cylinder, it's best to unhook the wire from it, before you tear down your ignition system and replace stuff. You just never know where anything electrical can fail.

It is good to see to it that this kill switch is in good working order though. The thought of shearing a flywheel off and sending off into your lap can spoil your day. JohnyRudes have heavy flywheels and they runaway easily.

As far as WOT issues, check your throttle linkage and make sure it is opening the carb up all the way. Poor adjustment is a common problem.

Leon

 

[freddyray21]

Re: What is this part on my 1957 35hp

Just as said it is a vacuum cutoff switch to prevent a runaway. If you have not checked both coils do so as they are always bad in the older ones unless they have been replaced. probably your issue with the wot.

 

[tashasdaddy]

Re: What is this part on my 1957 35hp

 

[1946Zephyr]

Re: What is this part on my 1957 35hp

Yea, these coils love to arc out on the armeture plates.

Looks like that did a good job of that end yet they still deliver a spark.

 

[tashasdaddy]

Re: What is this part on my 1957 35hp

no, those are coils that a wire got crossed, and they received 12 volts direct, to them. it sort of frieds them.

 

[wildmaninal]

Re: What is this part on my 1957 35hp

Both coils are in mint condition, there not new but they give out a good spark. Seems like I did lose spark on the one cylinder at one point before I even took the boat out to test it, I finally got the points reajusted and got the fire back. I guess I need to check to see if I lost fire by chance, what it is I stripped out one of the bolts that holds the points tight, so I had to resort to something else to tighten them down it may be failing again. I did do some adjustments to the carb linkage yesterday, I also am going to try to have somebody in the boat with me to adjust the carbs as putter along. I honestly didn't run it very long on the lake, my brother was in a rush to get home, he was kind enough to help me launch the old boat. I just don't think it was hitting WOT. I did clean the carb and replace the o rings if I remember right.

 

[jay_merrill]

Re: What is this part on my 1957 35hp

It is, indeed, a vacuum switch. Here's what a 1968 Johnson 33hp service manual (OEM version) has to say about it.

"If the throttle is suddenly closed while the motor is operating in neutral, crankcase suction may become abnormally high. This high suction (vacuum) will cause eratic functioning of the carburetor, allowing the motor speed to increase. The function of the cut-out switch is to short out the breaker point for the lower cylinder momentarily when crancase suction increases, preventing the bottom spark plug from firing and thus reducing motor speed. The safety switch completes the cutout switch circuit and prevents it from operating at full throttle."

I recommend that you get a factory service manual for your motor, if you can find one, for more information on this part. Try here at iboats for a manual, but there are also other sources.

 

[F_R]

Re: What is this part on my 1957 35hp

The vacuum cut-out switch won't work at all unless it is grounded. It is supposed to be grounded through the mercury switch on the throttle gear. If you just ground it without going through the mercury switch, it may cause misfiring at certain speeds, usually just under full throttle. The starter solenoid coil is also grounded through the same mercury switch by connecting to the same nut on the vacuum cut-out switch. The mercury switch limits both of those items to operating only at low throttle settings.

 

[wildmaninal]

Re: What is this part on my 1957 35hp

Thanks Jay, FR and the crew who chimed in. So it could cause a misfire if this isn't wired properly. I'll half to run a ground wire down to the solenoid as you mentioned FR. I only have one ground coming from the soleniod to the starter. I take it that I hook it to the same ground on the soleniod that goes out to the battery.

 

[F_R]

Re: What is this part on my 1957 35hp

No, it is grounded through the mercury switch. The mercury switch also grounds the solenoid. The common connection point is the vacuum switch housing.

Somebody may have long ago replaced your solenoid with a car solenoid and burned up the mercury switch. I knew I shouldn't have mentioned it.

 

[wildmaninal]

Re: What is this part on my 1957 35hp

The mercury switch also cuts the motor off once you idle down to a certain point right? Or is it just the fact that the carb is adjusted to where it is so low of and idle that the motor will shut off?

What I'm getting at is the motor will shut off when you bring the throttle down to idle. So if the mercury switch is supposed to be the reason the motor shuts down the switch is still good then.

I couldn't even tell ya what style soleniod I have on it now but I know it came off of an old boat which still had it's original fuse block where the soleniod is mounted, which it looked like it had never been removed.

The motor I'm actually talking about use to be a standard addition motor so it didn't have a starter until I recently mounted one on there. The motor in the picture is not the motor I'm working with, it is now and has been the parts motor for the motor in subject and was the easiest motor for me to get to at the time to take a picture the part in subject.

 

[F_R]

Re: What is this part on my 1957 35hp

No, the mercury switch function is strictly limited to what I listed. As you guessed, it just stalls when you get it down too slow to keep running.

 

[jay_merrill]

Re: What is this part on my 1957 35hp

The key difference between the two types of solenoids is that the automotive solenoid grounds through the base, while the outboard solenoid does not. Just because the solenoid that you are using came out of a boat, does not mean it is an outboard solenoid. The correct solenoid for you motor should ground through one of the two, smaller center posts on it - one is for the solenoid actuation circuit, and the other is the ground.

 

[wildmaninal]

Re: What is this part on my 1957 35hp

Here is a picture of the solenoid.

I failed to mention that the boat I got this solenoid off of had the same year motor and same hp as the motor in subject on this thread. I eventually sold that motor, a 1957 35hp Johnson, I wish I still had it even though it wasn't running when I sold it.

So I take the small ground wire from the solenoid and run it to the vacuum switch, I take the negative wire from the mercury switch and run it to the same spot that as FR showed on his diagram which the smalll negative wire from the solenoid is going to mount.

 

[wildmaninal]

Re: What is this part on my 1957 35hp

bump

 

[F_R]

Re: What is this part on my 1957 35hp

yes