Switching outboards on my boat

charakel

Seaman
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Jul 10, 2013
Messages
69
Hello guys, I am in the process of switching outboard motors on my boat. I currently have a 75hp Chrysler and am replacing it with a 115hp Mercury. I don't have the motor yet, picking up tonight. New motor comes with wire harness and controls, tilt and trim. I am looking for and tips, tricks or procedures in rigging?? I have never swapped motors before and am kinda lost..... With that being said I know I have to remove existing controls and wiring. Is it possible to cut wires that come out of the dash and splice into with new harness from the mercury? Or do I have to dig into the dash and do some major rewiring? The 115hp Mercury is going on a Sea Sprite 16ft Deck Boat. Thanks for any provided information!!
 

Alumarine

Captain
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Feb 22, 2005
Messages
3,684
What year is the merc?
Depending on the control that comes with the merc the key might be in the control and the tach connection might be at the front of the control.

Could be very little wire cutting needed.
 

GA_Boater

Honorary Moderator Emeritus
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49,038
Echoing Marc;

You shouldn't have the need to cut or splice any wiring with the remote control that comes with the motor.

What gauges do you have?

You may need tach signal and power, but that often comes from a 3 or 4 pin connector in the front of the control with an adapter cable.
 

charakel

Seaman
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Jul 10, 2013
Messages
69
The merc is a 1975 inline 6. The controls and wiring look fairly simple. Got the Chrysler loose and ready for removal. That's the tough part as I have no winches or stands
 

roscoe

Supreme Mariner
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Oct 30, 2002
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21,657
Sure , may work, but not easily or safely.
Com alongs are not made for lifting, or for lowering. And trees certainly don't have wheels on them so you can move the engine away from the boat, or align the new motor on the transom.
 

Alumarine

Captain
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Feb 22, 2005
Messages
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Sure , may work, but not easily or safely.
Com alongs are not made for lifting, or for lowering. And trees certainly don't have wheels on them so you can move the engine away from the boat, or align the new motor on the transom.

I wasn't saying it was better, just an option.
 

charakel

Seaman
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Jul 10, 2013
Messages
69
I'll be renting an engine hoist this weekend.. My concern now is the whole wiring. I have all the harnesses except the trim and tilt switch plate. Can I use my existing trim toggle switch that is dash mounted?
 

Alumarine

Captain
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Feb 22, 2005
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Is there no trim switch in the merc control?

In any case it's straightforward to get the trim working.
You did get the power trim assembly with the motor?
 

charakel

Seaman
Joined
Jul 10, 2013
Messages
69
No, It is a 1975-76 model control that has a separate switch for the trim supposedly. I did get the trim assembly and the wire harness with the red boot plugin that goes to the control.
 

charakel

Seaman
Joined
Jul 10, 2013
Messages
69
Update... I got the old Chrysler off and the Merc on and bolted up. Hooked up gas and water hose and it fired right up... Yes, Marc c, I believe I can make the old trim switch work. I got everything laid out... Should I make a new thread of my upcoming questions or continue here?? This thread is solved! :) Thank you all for suggestions and help.
 

GA_Boater

Honorary Moderator Emeritus
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May 24, 2011
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49,038
It depends.

If the questions are continued about the trim wiring/motor switch, keep those here.

If the questions are for something else, start a new thread because those not familiar with your issues may skip over this thread.
 

charakel

Seaman
Joined
Jul 10, 2013
Messages
69
Hooking up trim lines to the cylinders? I can't see the port in which to attach the hoses to. Are they in the back of the cylinder? On my stand alone Trim assembly there are 4 hoses coming off. 2 for each cylinder??
 

Alumarine

Captain
Joined
Feb 22, 2005
Messages
3,684
Yes 2 for each cylinder.
There should be 2 small hoses and 2 larger hoses.
1 small (Up) and 1 large (Down) goes to each cylinder.

There should be corresponding ports on the cylinders.
When routing the hoses and attaching them to the cylinder make sure they won't bind as motor goes up or down.
 
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