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