How difficult is a motor swap? (Newbie)

newcomlr

Petty Officer 2nd Class
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Jul 5, 2012
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125
Looking to buy first boat ever! A pontoon and on a budget. Found a reasonably priced 1980's Sun Tracker 24 foot. Has a (I assume) same era 40 hp 2 stroke Mariner outboard. I believe the boat specs say max is 75hp.

I'll be using the boat almost exclusively on a small lake, so the 40hp may be enough...i don't know until I've used it. Being a newbie, I was just thinking if I ever decide I want to replace the motor (or if it goes caput) I just find another motor suitable for a pontoon (shaft length, appropriate HP, etc.).

The lady at the boat dealer mentioned that motor swaps aren't that easy, and that if I was to say, replace the 40HP Mariner, with a 75HP four stroke non-Mariner, then I would have to replace controls all the way to the helm and possibly re-wire. She said I would probably have to find another Mariner of the same era to have a chance of not having to replace controls and wiring.

Is that true? Suddenly didn't sound like a DIY job, or an inexpensive proposition. I'm pretty good mechanically and an all-round can fix anything guy, but never worked on a boat before.

Thanks in advance for any guidance!
 

MH Hawker

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Jul 13, 2011
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Re: How difficult is a motor swap? (Newbie)

Outboard motor swaps on a toons are very simple, I changed mine out in about 4 hours by my self. Depending on what your swapping around yes you may have to also change out the controller, and if you do get another motor get the controller with it. I changed from a Nissan to a mariner on mine. So yes i had to change out the controller that added 30 minutes.

A 40 hp on a 24 footer should push you around at around 15 to 18 mph and thats a decent speed.

Sounds like a stealership. She has mixed in a good bit of truth and lies, if you have to change controllers , its all plug n play and most controllers will fit the same brand of motors, mariner and mercury will interchange, boats have 2 electrical systems one for the motor and one for ever thing else, so doing a motor swap is simple.

Sounds like she is trying to sell you a new motor to me, thier lots of decent used motors around. I would ask her what the compression numbers on the existing motor and when the last time the water pump was changed and if the lower unit would pass a pressure test, and watch her face real carfull.
 

BatDaddy1887

Chief Petty Officer
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Jan 18, 2009
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463
Re: How difficult is a motor swap? (Newbie)

You would need an engine hoist or perhaps the marina can use their fork lift with operator for a small fee. Then, you would need the correct cables for the new engine...hopefully they will come with. Then, steering cable needs to be re-attached to the new engine.
 

Tony T.

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Jun 5, 2007
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178
Re: How difficult is a motor swap? (Newbie)

I did this not to long ago, found a 1995 21ft Suntracker with a bad motor, It had a 95 70HP Force (by Mercury Marine) motor. I had a 1985 75hp Mariner outboard. Long story short everything plug and played right together except the power tilt and trim which wasn't to hard to figure out. Being that's a 24 footer your looking at it should handle right up to 115hp or 120hp maybe more. My 21 ft says maximum 90hp on the data plate.

ON EDIT: I used a cherry picker to do the swap on mine, no problems.

Tony
 
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Boss Hawg

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Apr 9, 2009
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1,433
Re: How difficult is a motor swap? (Newbie)

Pretty ez with the right equipment (as with any project)
I changed a 115hp to a 110hp on mine by my self in a day (long one) using a stick steer Bobcat - Not the ideal unit but its what i had available-
 

Jeep Man

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2,803
Re: How difficult is a motor swap? (Newbie)

I've installed two 60 hp Merc motors by myself without a lift of any kind.(first one was stolen) It's all in the planning. That aside, a Mariner is a Mercury with a different paint scheme. All the controls will interchange. Most Force motors will hook up easily as well, but that's not a direction you want to go in. If you switch to another brand, such as Honda, Evinrude, Yamaha, etc., It will be more difficult as the ignition, tach, etc., may need to change as well.
 

newcomlr

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Re: How difficult is a motor swap? (Newbie)

All great feedback! That helps a lot. I've pulled car motors before, but didn't think about the standard rental engine hoist probably isn't tall enough for a boat motor. I don't have the exact model of the motor, but the nadaguide.com site suggests the dry weight is less 200 pounds so I've got ways around that.

I'm hoping the Mariner motor that's on the boat works out. The boat will be on a small lake 99% of the time. I live in a private lake community, and the motors aren't allowed to be too noisy.

@MHawker, thanks for the extra tips on questions to ask the dealer about the motor. I doubt they will know much about it since they took the boat in on trade, but I think they have serviced it in the past some. The boat is on their dry lot, so I can't take it out for a spin, so I'll have to settle for just hearing it run. Another newb question...I assume they put a barrel of water under it to run the motor? any tips on what to look for (or do? or listen for?) in that environment.

@Boss Hawg (and anyone else who served): Thank you for your service to our country!
 

MH Hawker

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Re: How difficult is a motor swap? (Newbie)

Yes hearing it run is ok, but have them do a compression test. Wont take all of 10 minutes and have them drop the lower gear oil and inspect it. It should be dark or look like 90 W, milky white ( white is water contamanation) to honey color can be a sign water is getting in, if its been used on the lake it can be a bit honey colored from air mixed in but not if its sat several days. Again its a very simple thing to do and it will tell you if you are going to have to make expensive repairs.

On a set of muffs you cant tell if the water pump needs to be changed, the hose pressure will make it look ok or if the carbs need a rebuild or how much of the rings it has left. A on the water test is the very best way.

More than likely its fine 2 strokes last for ever if treated right. And Mariners are good motors and most parts can still be found.

Snickers I use a chain rachet and a old oak tree to change motors.
 

jergeo

Cadet
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Jul 5, 2012
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Re: How difficult is a motor swap? (Newbie)

Beings it is a dealer tell them you want a test drive before you buy it. You may not be able to drive it yourself but you will see how it runs and handles.
 

rogerwa

Commander
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Nov 29, 2000
Messages
2,339
Re: How difficult is a motor swap? (Newbie)

I've done one with an engine hoist.. Worked well.. Switching controls isn't that bad. If you have pulled auto engines, you can do this..
 

newcomlr

Petty Officer 2nd Class
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Jul 5, 2012
Messages
125
Re: How difficult is a motor swap? (Newbie)

Well, the boat I was looking at sold before I could get back to. Toons seem to sell fast here.

Looking at another on Sunday. newer Playbouy model with a 70 hp. Fingers crossed.
 

MH Hawker

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Re: How difficult is a motor swap? (Newbie)

Its that time of the year.
 

BatDaddy1887

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Jan 18, 2009
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Re: How difficult is a motor swap? (Newbie)

The boat will be on a small lake 99% of the time. I live in a private lake community, and the motors aren't allowed to be too noisy.

I've heard that 4-stroke engines are much quieter than 2-strokes.........
 

newcomlr

Petty Officer 2nd Class
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Jul 5, 2012
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Re: How difficult is a motor swap? (Newbie)

Update: Didn't like the Playbouy boat that much and it would need the deck replaced.

Just bought a 25' Party Barge with all aluminum deck and a newer motor and nice trailer! Paid a bit more, but should be set for a while!
 
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