I/O questions

[horndog]

I am looking at a 1978 boat with a 3.0 mecruiser I/O in it. Its 120hp and had a few questions<br /><br />1. What do I look for as far as any known problems?<br /><br />2. How relable are these motors/sterns?<br /><br />3. Is this motor a 2-cycle or 4?<br /><br />4. what kind of maintenance does this thing need?<br /><br />This is a freshwater boat and only will be used in freshwater<br /><br />Thanks!

 

[Bondo]

Re: I/O questions

A 1978 Should Be equiped with the 181cid, 3.0l, 140hp, 4cyl., 4-stroke/cycle....<br />And the Mod.1, or pre-Alpha outdrive...... <br />It's a Solid, Proven power package... Parts are Very Common, Easy to find,+ Inexpensive(in a relative way)..... that pretty much covers 1,2,+ 3....<br />4... Go to ebay,+ find a copy of the Merc. factory manuals for your motor/outdrive.... they're listed All the time.. You'll learn More than you'll ever need to know......

 

[horndog]

Re: I/O questions

thanks bondo! thank goodness I didn't buy that gallon of 2-cycle oil!<br /><br />When I go take a look at it I can get better specs<br /><br />I will find a factory manual!

 

[horndog]

Re: I/O questions

I am hearing conflicting horsepower ratings: dealer tells me 120hp and you say 140hp, so I look around on the web and see that maybe both were offered then? <br /><br />I am confused? Its not that big of a deal, but it would be interesting to find out<br /><br />Where can I find more info on the web about the horsepower ratings? I did numerous searches for 1978 3.0 on the web and nothing tells me the horsepower ratings

 

[crazyray]

Re: I/O questions

a 120 hp would have been an 2.5 L an 3.0 L would have been an 140 hp for that yr

 

[horndog]

Re: I/O questions

may I ask where you are getting this information from?<br /><br />thanks

 

[Tacklewasher]

Re: I/O questions

crazyray is correct.<br /><br />I have a mid 70's OMC that says 140 on the leg and the valve cover. Had it rebuilt and was looking for other parts (gaskets etc) and kept running into parts not fitting. Asked the rebuilder what he thought I had and was told a 2.5l, 120HP. Armed with that knowledge, I get the right parts.<br /><br />It also shows the two engine sizes and hp in the manual and OMC booklet that came with the boat.<br /><br />For the most part, the parts are interchangeable. The exhaust is different (which is where I had problems) but not much else.

 

[Bondo]

Re: I/O questions

There were two(2) 4 cylinder, 4 cycle, 4 stroke Chevy based engines used by Merc. ... <br />the 153cid/ 2.5l,+ the 181cid/ 3.0l...<br />the 181cid/ 3.0l survives today.. <br />the 153cid/ 2.5l has been extinct for a long time....<br /><br />"may I ask where you are getting this information from?"<br /><br />Just a few things I've picked up.....<br />If you bought a manual, You'd know this too....<br />Most manuals cover Both of these motors in the Same book, Because they are Very Similar.....<br />About the Only time you can Tell Which?? engine you have is,When you're trying to buy Parts.....

 

[horndog]

Re: I/O questions

the boat is not in my possession yet, so I have not bought a manual. I will double check when I take it for a sea trial in the next week or so. <br /><br />dealer still thinks its a 120hp 3.0l, but maybe he is confusing the 3.0l with the 2.5l hp rating

 

[Bondo]

Re: I/O questions

I understand..... My point is, It Doesn't Matter, Till you try to buy Parts....<br />You'll Never FEEL the Difference.....

 

[horndog]

Re: I/O questions

gotcha.. I probably won't do the repairs on it, call me lazy, rather send it someone that knows what they are doing

 

[horndog]

Re: I/O questions

I found out it is a 2.5L