Replacing mid 80's Mariner with "newer" Mercury?

[inboardnut]

First time poster here....

I have an older 20' pontoon boat with a mid 80's Mariner 50. I purchased a bass boat with ( I think an 2001) Mercury 50. I am planning to replace the Mariner with the newer oil injected Merc.


Note: I bought the Mercury from an estate and hasnt been run for approx. 4 years.

What "problems" could I encounter? A few things I'm concerned about:

1)The Mariner has external tilt pump and cylinders. Is the Mercs tilt is internal? Any problems here?

2)I want to replace the older Mariner controls to the one from the Merc.
Are cables compatible?
What about wiring?
Any other issues?

3) Planning to install new impeller in the Merc. Probably pull and clean the carbs.
anything else to be concerned with before trying to start it?


4) What about prop pitches? I'm not sure what either currently have on them.

Any other suggestions?
Thanks!!!!.

[boats.net]

If Merc is a power trim model then trim would be inside transom bracket.
Probably need to replace main harness and key switch, controls and cables may be ok but some Mariner models did use diferent cables and throttle was a pull to open.
Carb and fuel pump cleaning, impeller and lower unit oil should do it.
Prop pitch should be same as Mariner prop.

[inboardnut]

Thanks for the input! Been around boats a long time, but always had straight inboard ski boats so working with an outboard is a new experience.

We did get the motor mounted on the pod. Very nice to get rid of the external trim pump! I did take the controls out of the donor boat and re-located them on the pontoon.

We did get the new motor running before removing it form the donor, but it didn't want to idle.(I'm guessing carb cleaning is in order) Since the motor hadn't been run for a few years, I think I'm going to take it to a Merc dealer to clean the carbs and check out everything out to make sure it is dependable.

By chance, are props interchangeable between the two motors?
Thanks again!

[boats.net]

Prop may work if both have same diameter gearcase, probably will exchange washers as well.