1974 R-1 140 Outdrive Shift Cable and Kill Switch Adjustment

[bbook83]

After pulling the outdrive for gear seals and water pump replacement, upon re-assembly and start up I followed AChris’ sticky on adjustment. All started out well, but then the engine shut off while going into reverse on the muffs. After a few more tries, it started shifting into reverse without dying. However, I can see that the cam still has the switch depressed when in reverse, but it does not shut off the engine. It also does not affect the engine when in neutral and I depress the exposed switch manually.

I had some problems last season with the shifter not disengaging from both reverse and forward. I am starting to wonder whether operation of the kill switch was sporadic then. I don’t know if it is still possible to get a switch, but I will try to find one. I know this one is the original, as I bought the boat new. Yes, I am old.

My questions relate to reading on this board that a kill switch will not work on muffs running on the trailer. Is that true? If so, why? I also am concerned that with a working kill switch, the engine will die because the position of the activation cam will depress the switch. Pictures of the linkage and switch are attached. The last one is while shifted into reverse. It doesn’t appear that moving the linkage post up further will change the cam position enough. Are there other adjustments that can be made? You can see in the pictures there is a bolt with a slotted hole and another below it. Can the shutoff cam be adjusted there?

 

[achris]

That's not the interrupt switch, that's the reverse lockout switch for the trim system (so you can't trim up/out while in reverse)...

 

[achris]

...My questions relate to reading on this board that a kill switch will not work on muffs running on the trailer. Is that true?

Yes.

If so, why?

Because the switch will only activate when there is a load on the cable attempting to restrict it's movement. That load is caused by the undercuts on the dog clutch (inside the gear housing), and they are only going to create a load if they themselves are loaded, and that's done by the prop trying to push water. No water, no load.

However, there is one time when you are on the water when the interrupt switch won't activate, and that's when you are still moving forward (or backwards) as fast or faster than the prop would be pushing you. The drive is effectively in overrun. Same as a diff in a car. That removes the load on the undercuts, and thus the load on the cable, no need to interrupt when shifting to neutral.

Chris.....

 

[bbook83]

Well, that is embarrassing. The attached picture is of the interrupt switch, correct? If I depress the switch while running on the muffs, if it is working, will it kill the engine? Other than that test, it appears I will need to be out on the water to test the interrupt. If there is a problem with the switch, would that potentially explain the problem of not disengaging last year? FYI, the switch is no longer available. It looks like a few still out there on the likes of eBay at prices as big as $250.

 

[DarrinT]

I have the same problem with my 73 Islander 140 merc
Bin through 2 of those switches
The fix from Merc is an ugly contraption that costs $150 clamps onto the engine beside the carb/intake that I hated and pulled off when I repowered.
Once upon a time there was a way of modifying an easily available switch that looked the same but to use in this application needed a fabbed backing plate and a strategic hole drilled through it and was posted to the Mercruiser forum.
Unfortunately the link to the pics no longer exists and I got stupid and never downloaded them.
I'm going to refit my boat and make an attempt to reproduce it from memory/Mcguyvering.
For 3-4 yrs I've been shutting off the engine to switch for-rev gears.
Very entertaining for the on lookers when manuvering in harbour and you better have yur engine tuned so she start immediately!!!

 

[DarrinT]

This is the switch that was used to modify

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octopart.com

This was the old link to the method of modification

1998 Mercury 150efi Offshore Ideal RPMs?

I have a 1998 Mercury 150efi offshore on my 21' Striper Cuddy. The motor runs perfect, idles perfect, and starts just like a car everytime. It has plenty of power for my boat. I was wondering what the ideal RPMs are to run this motor. On my most recent trip I ran it at 3500rpms and I was going...

forums.iboats.com

The link now goes elsewhere drat.

 

[bbook83]

Thanks for the link to the potential alternate switch. Does anybody know if just a simple continuity test is sufficient to test the switch?

 

[1960 Starflite]

Thanks for the link to the potential alternate switch. Does anybody know if just a simple continuity test is sufficient to test the switch?

All the switch does is ground the + side of the coil to make the engine stumble for a second so the dog-tooth gears can release. Take the wire off of the coil, put a muti-meter test lead on the wire, attach the other lead to a good ground. Set the meter to Ohm scale, operate the switch, meter should show full ground.