3.0 and 2.5 questions

hello all<br /><br />i have a 3.0 merc with a cracked block, it is from a 1985 boat, i was wondering if it is possible to put a 2.5 in it's place if i cannot locate a block within a reasonable price, and if anyone would know what differences i might come across between the two, <br />also does any one know what years the 3.0 stayed with a 2 piece rear seal i am looking at a 1994 block and wondering if it will work for me, and i have been told, that the 3.0 had different head designs in it's time so i am not even sure if my head will fit on the 1994 block. any information would be very helpfull.<br /><br />Thanks.

Re: 3.0 and 2.5 questions

Fickett:<br /><br />You've asked a lot of different questions - it would be helpful to know the pertinent engine model details about your current motor, as well as the '94 motor your considering. Believe me, the more experienced (read: professional) guys on this forum are going to require this info in order to effectively answer your questions.<br /><br />With regard to your question about substituting a "2.5 in it's place", are you thinking about just a 2.5L block and using your current heads (which I'm pretty sure won't work), or an entire 2.5L engine swap? That would most likely necessitate an outdrive swap, too, as the 2.5L is an older Mercruiser setup, and you're better off moving toward newer (not new, per se, just newer) equipment if you're going to start swapping out major pieces. There are several sources of complete longblocks on the internet for less than $2,000. Check out this site: http://rebuilt.net/Inboard_Marine_Engines.htm and Dogpile or Google for others.<br /><br />I'm not sure about the rear seal, but I think that GM started producing the 3.0 with the 1-piece rear seal in 90 or 91.<br /><br />Mercruiser made two versions of the 3.0 from 90-94: the 3.0L is a 115hp variant utilizing the 3.0 liter block and 2.5L heads, while the 3.0LX (135hp) used the same block and 3.0L heads. The '94 motor you're looking at will be one or the other.<br /><br />Here's a link (courtesy of Don S) that will give you some information on engine identification and block/head combos:<br /> http://www.boatfix.com/merc/Bullet/97/97_06.pdf

Re: 3.0 and 2.5 questions

Hi Fickett,........ Welcome to the forums here at iboats.com.......<br /><br />Where abouts in the land of Maineiacs are you hailing from,.??...<br />I was born,+ raised in Old Town.......<br />

i was wondering if it is possible to put a 2.5 in it's place

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Ayuh,..... That's Possible....Complete Engines anyway,.. The Blocks are Not the Exact Same, Internally........Externally they Are the Same.......<br />The only Visual Difference I know of is;<br />The 3.0l has a Harmonic Balancer mounted to the front of the Crankshaft,.. The 2.5l has Only a Pulley.......<br />

also does any one know what years the 3.0 stayed with a 2 piece rear seal

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I'm Not Sure of the Years,....<br />But,.....<br />The Differences Are Adaptable using a Retrofit Coupler.........Sierra makes such an adapter coupler.......<br />

that the 3.0 had different head designs in it's time so i am not even sure if my head will fit on the 1994 block.

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Ayuh,.... There's Alot More different Heads than most of the fellows here even Know About,......<br />They'll All interchange,... Just some Flow better than others..........<br />BTW,..... Your 85 head is 1 of the Better heads..... <br /><br />I've got this 1 sitting on My shop floor,+ It's Looking for a New Home........<br />It's out of an 84 boat,+ was running Great with removed,....<br /><br /> <br /> <br /> <br />I'd love to let it go for about 1/2 the # that Dave says a New Long Block goes for.......<br />'Course,..... This is a Complete Plug & Play crate motor........