OMC engine to Merc outdrive

[Estradatj]

Hello everyone,<br /><br />I just finished swapping the motor in my Mark twain T160. I replaced the original Mercruiser 140 inline 4-cylinder engine with an OMC 120 inline 4. I’m looking for advice on adapting the cooling and exhaust system on the OMC to the Merc.I have some ideas of my own but am a mechanic novice.<br /><br />One of the things that has me baffled is exactly how the cooling/exhaust system works. It appears that the water comes in and goes out through the same elbow on the back of the manifold. Is this a correct assumption? I can see that there is an inner and outer wall inside the manifold and the elbow has a smaller hose that Ts off from it before going connecting into the outdrive.

 

[Boomyal]

Re: OMC engine to Merc outdrive

Don't know how your model is for sure but my 800 series has a 3/4" hose coming up from a fitting on the intermediate housing to a tree atop the thermostat housing/elbow. From there the water went to the engine and back into the front of the exhaust manifolds and on out the rear of the manifolds to expel thru the outdrive. Yours is probably similar. The double walls in the rear manifold elbows are for the exaust and the expelled water to exit. Water in the outer ring and exhaust thru the center.

 

[JB]

Re: OMC engine to Merc outdrive

Moving to I/O

 

[Bondo]

Re: OMC engine to Merc outdrive

Use the Merc. Acc. off your old motor....It'll be a whole Lot easier.... <br />And Yes, Everything Should fit just Fine....

 

[Estradatj]

Re: OMC engine to Merc outdrive

I wish I could use the parts off of the old motor. Unfortunatly this is a boat that I drug away from a boat repair shop. They had taken a lot of the motor for spare parts. All I have is the cracked block, distributor, alternator, and a few other electronic components. Anything not bolted to the block was removed.<br /><br />Can't complain much though, the boat was free as long as I could haul it away. All other components on the boat seem to be in working order. Even the hydraulic trim works! <br /><br />I was thinking of just getting a really long high temperature hose and trying to rig it up between the OMC elbow and the Merc outdrive exhaust. Any reason this wouldnt work?<br /><br />There were two hoses on the OMC motor and Two hoses on the MERC out drive. One of the hoses is the same size on both and I suspect is the water intake. The other is close in size adn I think is the exhaust. The problem here is that elbow on the OMC and the exhaust on the MERC are very close together.<br /><br />Thanks for any and all replies!