140 to 120 Mercruiser Engine Swap

[smiles16]

Hello All,

I am new to the forums so please excuse me if I am am posting in the wrong place.

Anyway, I have a Mid-80's Sea Sprite I/O I am bringing back to life. I also have an early 70's Sea Ray that will be donating parts.
I bought the Sea Sprite from a friend for $500 knowing the head was cracked on its 140 Merc. The Alpha One looks to be in great shape so no worries there as of yet. I bought the old Sea Ray for $600 from my marine mechanic friend because it had a known to be good Mercruiser 120 and alpha one in it. Please don't beat me up too much I know I am downsizing in HP, but I have read these would be easy swaps.

Now that you have the story, I have two loaded questions....

Does anyone know the steps and procedure to pulling and installing these engines? (I read about gimbal bearings and engine alignment? :noidea
-AND-
Is there anything I should replace for precautionary reasons while I have the motor out of the boat? (Bellows, hoses, etc.)

This is my first I/O boat so I am as fresh as it gets, but I am mechanically inclined. Help?

 

[Rick Stephens]

I don't see any big deal to your swap. Go through everything, especially at the transom plate while the motor is out. You can access the transom plate easily, so then is the time to inspect everything. If the water intake hose is hard, this is a good time to replace it. Ditto on checking the lower shift cable. It is the number 1 most commonly replaced part after the impeller in the drive.

Rick

 

[smiles16]

Thanks Rick. Please tell me if I am correct.

So all I have to do is shift into forward gear, remove lower (6 bolts), undo all connections, and remove 3 motor mount bolts. Then slide forward and out and install in reverse order.

???

 

[Fishermark]

There are two bolts in the back and then the front mount. It is better to leave the front mount attached to the engine and simply remove the bolts holding the front mount in place. Depending upon your boat, they will usually be either a couple of lag bolts, or maybe a couple of bolts with nuts. Either way, that makes four bolts to remove.

 

[Rick Stephens]

If you haven't run the replacement motor - they are REALLY easy to run sitting on the floor. Lots easier to check everything outside of your motor bay than inside. Hook up water, fuel, attach a battery and fire it up. I use a spare merc wiring harness, but you only need connect positive to starter and to the + side of the coil to run.

https://youtu.be/HMag9SbwpD4

 

[Bondo]

Then slide forward and out and install in reverse order.

Nope,.... The 1st, 'n last motions are straight up off the rear mounts, 'n straight back down on 'em,.....

That's why ya pull the drive 1st,....