Installing 115hp Merc - any tips?

[bexi]

Hey guys i've bought a 2nd hand 1983 Mercury 115hp blue band to replace my 1977 model one.
My friend and i are going to remove current engine and replace with our new motor this weekend coming.
anyone got any tips we should be aware of?

 

[AMD Rules]

Re: Installing 115hp Merc - any tips?

My quick thoughts...

- use safe lifting techniques. Those motors weigh in excess of 300lbs, and the last thing you want is to end up with your toe between the skeg and the ground.

- it is quite likely that you need to insert the steering cable into the pivot bracket -before- you final mount the new motor.

- use recommended methods to fill any unused holes left from the old motor (trim?).

- Stainless steel bolts and hardware only.

- Be sure to seal up the holes around the bolts. Remember the lower bolts are underwater at rest. I use 3M 4200 but others may have thier own preferences. I make sure there is a lot in the whole through the transom and more on the surface inside & out. Wipe up excess after tightening the bolts.

- Antiventialtion plate above the prop should line up with the bottom of the hull (on most boats) or just slightly higher.

- Make sure battery connections are clean tight. Suggest you replace any battery terminal wingnuts with permanent nuts & lockwashers. Be extra careful not to reverse the polarity... the electricals are sensitive to polarity especially the rectifier.

- Check to make sure the motor will full turn left/right and trim full up and down without risk of binding on any wires/cables.

 

[Chris1956]

Re: Installing 115hp Merc - any tips?

Bexi, Check the mounting holes. Somewhere along the line Merc standardized them. The '77 has the old style 3/8" bolt holes (six bolts if you have PTT), plus a transom clamp. The newer style is 4 1/2" bolts, and no transom clamp. If the boat wiring harness fits, it should work OK. The controls will work OK as well. PTT will likely be different. Steering and control cables will be compatable

 

[bexi]

Re: Installing 115hp Merc - any tips?

so i may need to drill the holes a bit bigger for the 1/2" bolts?

what should i use to fill in old unused holes?

 

[Chris1956]

Re: Installing 115hp Merc - any tips?

If the newer motor has the 1/2" holes, the old holes are in the wrong place. Fill 'em with marine silicone.

 

[bexi]

Re: Installing 115hp Merc - any tips?

i'm pretty sure the bolts on my '77 model are half inch.

is this not possible on a '77 model?

if they are half inch, does this mean the new motor has same mounts?

 

[Chris1956]

Re: Installing 115hp Merc - any tips?

The bolt holes on the two may be the same, or may be different.

The bolt holes on my '77 Merc 1500 were 3/8", and different than the standard bolt holes of the more modern motors.

Yours may have been altered.

 

[jimmbo]

Re: Installing 115hp Merc - any tips?

The 1983 engine will bolt on just fine. 1984 was the year Merc switched to the OMC bolt pattern on the inlines.