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  1. #1
    Petty Officer 2nd Class Chevyboy454's Avatar
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    Default I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Bought another boat and it's got a 2.5l inboard. I've always owned outboards so this is relatively new to me. Sure looks like the engine in my old S-10. Can I just get a 2.5l from an S-10 and swap it out??

    Thanks Rick.

  2. #2
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Nope, they aren't even close to being the same engine. For one, your boat engine has the intake and exhaust ports all on one side of the head. Your S-10 did not.

  3. #3
    Petty Officer 2nd Class Chevyboy454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    I understand the head is different, I suppose I should have worded it better. I mean usage of just the block and transfer all the other stuff over?

    Cheers Rick.

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    Commander RogersJetboat454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Quote Originally Posted by Chevyboy454 View Post
    I understand the head is different, I suppose I should have worded it better. I mean usage of just the block and transfer all the other stuff over?

    Cheers Rick.
    Engine in the boat is a Chevy/GM industrial engine
    Engine in the S10 is a Pontiac cross flow/tech 4/ "Iron Duke"

    Please read:
    http://en.wikipedia.org/wiki/Chevrol...ylinder_engine
    http://en.wikipedia.org/wiki/GM_Iron_Duke_engine
    1976 Rogers Custom Boats 18' "Bonneville" W/ Chevy 454/ Berkeley 12JC

    Care Taker of 1976 Glastron V-184 Crestflight W/ Volvo 170B/280 I.O.
    & 1969 Starcraft W/ 1956 Evinrude 7.5hp Fleetwin.

  5. #5
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    No, the marine engine is not based on a auto/truck engine. The marine engine is based on an industrial engine.

  6. #6
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    No, but the 2.5L 120HP is literally a dime a dozen. Just get a rotted boat and pull the motor.
    1988 Four Winns Sundowner 235, 5.7-4V 260HP OMC Cobra
    1977 Glastron V-184 Crestflite, 165HP Inline Six Mercruiser 1
    1978 Sea Ray SRV-195 Closed Bow, 165HP Inline Six Mercruiser 1, Awaiting Engine Transplant.

  7. #7
    Petty Officer 2nd Class Chevyboy454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Bummer, found a 2.5l in perfect running order in an S10 for 100 bucks, guess I won't be buying that one. Rotted boat is an option I'll have to look at, down side is what to do with the hull afterword..

    Thanks Folks!
    Cheers Rick.

  8. #8
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Are you sure it's blown?

    What are the symptoms -- could just be a gasket or something -- these engines usually rot out before they wear out or blow out --

    Sorry, you can't use an S-10 block -- it's totally different technology..
    The boat 2.5 is the "stovepipe" design whereas the truck version is the "iron duke" design..
    The head deck on the boat engine will not match up to the block deck on the truck engine..
    The push rods are in slightly different locations and move at a different angle..
    The cam is an automotive cam and the marine cam from your boat block won't fit..


    Now that said, if you can find an old '60's chevy II nova with a 2.5 (or 3.0) 4 cylinder, THAT engine would work -- just swap your marine cam in (I'd recommend using the lifters from your marine block as well since they are worn in to your marine cam -- keep them in the same positions), install brass freeze plugs, and swap your oil pickup tube and oil pan onto it.. DO NOT use automotive alternator, starter, fuel pump, or carburetor....

    Hope this helps...
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    Holy Crap! Even my weed-eater laughs at me now!
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  9. #9
    Petty Officer 2nd Class Chevyboy454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Don't know what the symptoms are as I finally picked it up last night. Guy doesn't have a clue whats wrong with it other then his tech said it was blown. I'm going to see whats up tonight with it. Bugger part is I was given one of those old 2.5's long ago and turfed it, went with a 350 in my Nova. I'll keep you posted.

    Cheers Rick.

  10. #10
    Petty Officer 2nd Class Chevyboy454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Update: Well the engine is whopped. She is seized up. I can get her to tun a little with a bar in each direction but it locks up. Feels kind of like a thrown rod or something along those lines. As for a free boat with an inboard that works (I've been on the used sites all summer lookin for a bigger boat) There is nothing around here. Even if it has any sort of part on it that looks useable people expect to get paid. Oh well Guess I'm in the market for a good used 2.5 or 3.0. Anyone got a spare one kicking around for relatively cheap lol. On the bright side there is 3/4 of a tank o gas in it!

    Cheers Rick.

  11. #11
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    You do have the outdrive removed because the drive can be siezed not the motor
    NO PERSONAL QUESTIONS, THIS IS WHAT THE FORUM IS FOR.

  12. #12
    Petty Officer 2nd Class Chevyboy454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    I plan on pulling it tomorrow to have a look. Just talked to the guy and he said there was a crack in the block that was repaired and his tech says must have leaked internal, hydro locked and bent a rod or something. Funny as the oil looks relatively clean with no debris. I'll know more tom.

    Cheers Rick.

  13. #13
    Petty Officer 2nd Class Chevyboy454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Thanks BT Doc!! You were correct. Engine is a runner, the repair to the cracked water jacket is leaking a bit but it does run. Seems a little hard to start but I suspect carb is gummed up. With the water on and plugs out I do not see any water in the cylinders, nor is there and evidence on the plugs of it not burning properly. Oil is clean and not milky so I suspect the engine will do me for a while. Now to find an electo shift OMC stringer drive. I am not fond of the electro shift setup but beggars cant be choosy!

    Cheers and thanks again! Rick.

  14. #14
    Commander RogersJetboat454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    This thread is posted as;
    I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Yet....
    Quote Originally Posted by Chevyboy454 View Post
    Now to find an electo shift OMC stringer drive. I am not fond of the electro shift setup but beggars cant be choosy!
    Somethings not adding up here!?
    Did the previous owner not know what he had?
    1976 Rogers Custom Boats 18' "Bonneville" W/ Chevy 454/ Berkeley 12JC

    Care Taker of 1976 Glastron V-184 Crestflight W/ Volvo 170B/280 I.O.
    & 1969 Starcraft W/ 1956 Evinrude 7.5hp Fleetwin.

  15. #15
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Just a guess, but maybe he reworded his post here to get more results. I posted my OMC problems on the OMC section and it takes 2-3 days to get a reply unlike 1-3 hours here........
    1988 Four Winns Sundowner 235, 5.7-4V 260HP OMC Cobra
    1977 Glastron V-184 Crestflite, 165HP Inline Six Mercruiser 1
    1978 Sea Ray SRV-195 Closed Bow, 165HP Inline Six Mercruiser 1, Awaiting Engine Transplant.

  16. #16
    Petty Officer 2nd Class Chevyboy454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    I'm going to assume he did not know the engine still ran. The way he explained it he has had nothing but grief from this boat this year and just wanted to be done with it. Too bad the crack in the block is still leaking. I'll have to pull the manifold and see what can be done there to stop the leak. Don't even know if I want to keep it yet, guess that all depends on how much the foot is going to cost me.

    Cheers Rick.

  17. #17
    Petty Officer 2nd Class Chevyboy454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Quote Originally Posted by Fordiesel69 View Post
    Just a guess, but maybe he reworded his post here to get more results. I posted my OMC problems on the OMC section and it takes 2-3 days to get a reply unlike 1-3 hours here........
    No I didn't reword the post, I was told by the original owner before I bought it it would need an engine, so before I even had a chance to look at it I asked if an S-10 engine would work. His "Marine tech" was wrong, turns out the outdrive was seized. I hadnt looked at it and assumed it was a Merc, didn't know it was OMC until I actually got it.

    Cheers Rick.

  18. #18
    Rear Admiral Fishermark's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    Quote Originally Posted by Chevyboy454 View Post
    didn't know it was OMC until I actually got it.
    Electric shift stringer at that!

  19. #19
    Petty Officer 2nd Class Chevyboy454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    I can assume this is not a good one? As I said before I/O is all new to me, I know the old Johnny/rude setup was a pain in the outboards so I am assuming the inboards are just as bad?

    Cheers Rick.

  20. #20
    Rear Admiral Fishermark's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    About as bad as it gets.

    Regardless of how good or bad they were when new - the real bad part now is finding a competent mechanic who can or will work on one for you. They haven't been used in decades - and the company is out of business. Plus the transom cutout is completely different so you cannot easily change to another type.

    Other than that... no problem!

  21. #21
    Petty Officer 2nd Class Chevyboy454's Avatar
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    Default Re: I/O Merc 2.5 Blown. Can I use a 2.5l block from an S10???

    That's Awesome! Guess I didn't get such a good deal on a boat after all. Anyone want to buy a 18 foot Sea Sprite REAL CHEAP! Pics Here -> http://forums.iboats.com/showthread....28#post3439828

    Maybe I should just stick to my outboard

    Thanks for all the info guys! Glad to be a part of this great community!
    Cheers Rick.

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