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Thread: Repowering question

  1. #1
    Member hntr's Avatar
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    Default Repowering question

    I have to replace my 2001 5.7 liter mercruiser. I've been looking around and am comparing marine engines locally and online to automotive engines from NAPA, Autozone Etc. Would I actually be saving money by going with an automotive engine and then buying the parts to make it suitable for marine usage? Or should I just but the marine long block and be done with it?

  2. #2
    Sponsor potbuilder's Avatar
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    Quote Originally Posted by hntr View Post
    I have to replace my 2001 5.7 liter mercruiser. I've been looking around and am comparing marine engines locally and online to automotive engines from NAPA, Autozone Etc. Would I actually be saving money by going with an automotive engine and then buying the parts to make it suitable for marine usage? Or should I just but the marine long block and be done with it?
    check these out
    http://www.engines1.com/gm_marine_crate_engines.html

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    Go with a marine engine. The cams are different and set up for the power curve for boats since they operate at a higher output level regularly. How many hours on your engine? If you're handy, a rebuild might be the way to go. If it's heavily rusted on the outside, that's another story. A machine shop can do the heads and if not too many hours, the bottom end might just need bearings, a new oil pump, timing chain and rings. Inspecting the insides will tell if it's rebuildable. I've done three and spent about one grand on everything each time since the cylinders and major components were still within tolerances even with 1500-1700 hours on them. It's been a few years and prices have gone up but still cheaper than new. Good luck!

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    Premium Member kasilofchrisn's Avatar
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    If you buy a new Mercruiser before December 31st they are throwing in 2 extra years of free warranty.
    I have to repower mine and I had Marine services in Homer order it for me and they are going to do the install.
    That will give me 3 years of factory warranty should anything go wrong.
    "The closer I get to nature the farther I am from idiots"

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  5. #5
    Member hntr's Avatar
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    One side of the engine had saltwater leaking in trough a cracked manifold. A friend scoped it and it is rusted and pitted and a compression test showed around 100 psi. So if I can get a automotive crate engine for 1500 and put in a 200 dollar cam as opposed to a 3000 marine long block it sounds like I'd be way ahead if friends can help with the labor. Is the cam the only difference?

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    Marine engines come with brass or bronze freeze plugs and the head and intake manifold gaskets are also set up to prevent electrolysis problems but as long as you're fresh water cooled, you should be OK. Some marinizers also change out the oil pan but don't know if that's due to the installation angle for proper lubrication. The Mercruiser I had was aluminum, better for a wet bilge. Hope this helps but you should check around some more and hopefully others will chime in here to help out.

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    Member Sobie2's Avatar
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    Go ahead and buy the cheaper automotive engine and let us all know how it works out. This will give us a difinitive answer on this topic which shows up every year.

    But if you can buy from Mercruiser on a payment plan and can afford the payments ($150/mo) then that'd be my answer.

    My general boating advice is don't look at the total big number "Why that cost $10,000" instead break it down monthly, it doesn't hurt so much that way.

    Sobie2

  8. #8

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    Quote Originally Posted by Sobie2 View Post

    My general boating advice is don't look at the total big number "Why that cost $10,000" instead break it down monthly, it doesn't hurt so much that way.

    Sobie2
    I realize that's how most folks do it these days. I guess I'm old fashioned and like to pay up front, with cash. Really helps the bottom line in the long run to not have those payments to make, with interest too! (grin)

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    Default Stay with marine

    We have watched a number of automotive engines die because thay are not ballanced the same as a marine engine.This is a key factor .All the rotating gear in a marine engine is taken out and ballanced together perfectly , some guys even have their engines blue printed but that' doesn't make any long term difference . Boat motors normally tollerate 4-5,000+ RPM, wide open throttle .automotive engines don't go much over 3,000.Boat motors ar equivelant to a truck climbing a hill with no end in sight, where as automotive engines have the advvantage of going down the other side, or coasting on the flat once in a while. Very different applications . On some situations where the engine suffered freezing and block dammage we have taken an automotive engine BLOCK and transfirred the ballanced marine rotating gear to it successfully many times for customers.

  10. #10
    Premium Member kasilofchrisn's Avatar
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    Quote Originally Posted by 270ti View Post
    I realize that's how most folks do it these days. I guess I'm old fashioned and like to pay up front, with cash. Really helps the bottom line in the long run to not have those payments to make, with interest too! (grin)
    Thats what I am doing with mine. I figure if I cannot afford to fix my toy should I really have it?
    I know that will open a big can of worms with some people but I like to live debt free as much as possible.
    I put down $6,000 on my new motor and will pay the rest after install for a total of about $8,000.
    It sucks to be out that kind of $$$ from my savings but I love my saltwater fishing and my wife agrees we need a saltwater boat.
    My last motor I believe was an automotive conversion. It just didn't last long and I really am not a mechanic so can't explain why but the posts by others sound plausible.
    This time around I am looking forward to having that factory warranty. I feel that after the last motor issues I had I would rather spend the $$$ for the factory motor with warranty than try to save a few $$$.
    Do shop around for your motor though. I have found Marine services in Homer beat the Soldotna shop on prices hands down on parts. In fact Marine Services sold me my last prop for less that the Soldotna shop could buy the exact same prop for at their cost not including dealer mark up.
    "The closer I get to nature the farther I am from idiots"

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  11. #11
    Member L. G.'s Avatar
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    Quote Originally Posted by Sobie2 View Post
    My general boating advice is don't look at the total big number "Why that cost $10,000" instead break it down monthly, it doesn't hurt so much that way.

    Sobie2
    That is an excellent way of looking at things.

    When you look and cost of ownership and maintenance vs cost of operation of a motor over, say, a 10 year, 1,000 hour life cycle, you'll find that the fuel bill trumps by a large margin.

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