4.3L Vortec mercruiser cracked block - swap with automotive engine block?

Discussion in 'DIY Marinizing' started by mmanning63, Jun 19, 2010.

  1. Frosty

    Frosty Previous Member

    Did you know that there is 2 engines. One is a 2 valve head the other is a 4.

    Head configuration and valve operation is chalk and cheese,This is why they can increase HP through such a range. Both engines are covered in my manual.

    315 is max constant marine rating is less.

    The pumps have pre and post turbo boost diaphragms and is very externally adjustable with double stage injectors.

    Who told you they were beefed Up?
     
  2. whitepointer23

    whitepointer23 Previous Member

    no i didn't know that, i have learn't something new. i have experience with the 1hz engine in landcruisers but i haven't seen the 4 valve engine.
     
  3. broke_not
    Joined: Jun 2008
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    Location: North Dakota

    broke_not Junior Member

    I think that's only where a small part of the confusion comes from. A much larger issue, is the use of terms like "special". A simple search of this forum's marinizing threads will illustrate that. The word 'special" is tossed around as if it has some meaning, and it's done a whole lot of the time by people that supposedly work on marine stuff for a living.

    If you're a marine tech, don't use 'special" unless you can provide details as to what that means. If you're a marine tech, prove a component is "special" by posting up an easily-researched part number. I've heard more hooey and hogwash from marine mechanics that probably any other type of wrench-turner that exists.

    And if the OP indicates that he or she already has a boat with an engine that has an issue, there's no need to tell them how expensive a starter/alternator/carburetor/fuel lines/whatever costs...because they already have those bits. And the often-mentioned camshaft? Puleeze. If someone is capable of removing/installing an engine, then swapping out a cam and lifters is nothing.

    This isn't simply about being cheap or wanting to create a dangerous or unreliable situation by bolting on stuff that is inappropriate for a given application. It should be about an exchange of accurate information. Nobody can tell me, (or anyone else for that matter), how much a used engine or individual component will cost them. No 'expert" in the field can determine from afar via their computer whether or not a swap is worthwhile unless the person making the original post says right up front that they're clueless, not mechanically-inclined, and will have to trust a seller's word that a used engine is sound....and then has to load it up and haul it somewhere and pay someone to add necessary bits and pieces and then drop it in.

    It's almost as if marine techs everywhere are afraid that the proverbial cat will be let out of the bag if accurate information gets out, because then the oh-so-easy unbolting and bolting up of a few basic parts becomes "do-able" for a DIY-er.....no "boat engine" magic wand required.

    I'm not trying to convince anyone that buying and swapping in a used engine will create an "as-new" situation, but here's the thing: The last boat engine swap I did, was done because the engine wasn't winterized and the block cracked as a result. Now if the freezing/cracking had NOT occurred, that same boat would still be on the water today with its, (egad!!), seven-year-old "used engine" installed. The owner would be using it happily and having no issues whatsoever. Instead, the block got cracked because of an oversight before laying the boat up for the winter. So he has a couple of avenues he can pursue: He can spend a lot of dough and buy a new or re-man engine and have a "better" powertrain than he had before....OR....he can spend a LOT less money and buy a used engine in approximately the same condition as the one he had was in before it was ruined. He can swap a few parts easily, and be back on the water....same as he was before. If we are making the INCORRECT assumption that a used engine is *automatically* tired and worn out just because it's used, then any engine in a car/truck/boat THAT'S CURRENTLY IN USE is also "tired and worn out"....despite the performance and reliability we see from it telling us otherwise.

    So there you go.

    ;)
     
  4. lilrobobx
    Joined: Aug 2011
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    Location: Hope Mills, NC

    lilrobobx Junior Member

    I say im gonna I agree there...i have yet to see or witness proof that there are major differences in the engines...ALTHOUGH, there are a few upgrades or what not that i would personally do to an auto engine before putting it in a boat, RUN the correct spark plugs with the correct gap, make sure the timing is correct, put a good oil pump in it HV standard presssure, if its an engine from a car...put a good cam in it (RV/Towing cam) nevermind the head gaskets, cause i ordered a set of auto and marine gaskets so now...i don't give a **** what any of the so-called marine mechanics say....they are the same damn thing...oh yeah...and put some good oil in it....all of which I tried the wrong and right way...and learned....and i have proof in my garage...looks like a 4.3l v6 cemetary.
     
  5. lilrobobx
    Joined: Aug 2011
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    Location: Hope Mills, NC

    lilrobobx Junior Member

    oh yeah...there is one detail i did notice while working on all those engines, all the marine engines are painted with a thicker, more glossy black finish versus the automobile engines satin finish. they even paint the plastic timing and valve covers....im guessing thats $2000 paint!
     
  6. Frosty

    Frosty Previous Member

    The real difference is when the engine is a raw water cooled marine engine,-- or sealed as US call them.

    I have not seen a raw water system for years and would frown on such a set up. I learn from these pages that they still exist in USA.

    If its a 'sealed' system the engine does'nt give damn where it is.

    The only other thing I would be concerened about is the "right " cam its must be able to stop reversion or your valves and even cylinders can suck sea water from the secondary cooling system back in.

    The offshore guys with high HO cams and dont care do not have the water exiting inside the exhaust. This would kill the motor real quick.
     
  7. powerabout
    Joined: Nov 2007
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    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    In the small block chevs the head gaskets are shim stainless and need to be in a raw water cooled engine.
    Try it with yours, leave them outside and see if the fire ring goes rusty?
    Unless GM has the same part number for their marine engine as the automotive one then you have your answer?
     
  8. Frosty

    Frosty Previous Member

    Yes it would go rusty --along with the head and the block.
     
  9. IMP-ish
    Joined: Jan 2011
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    Location: united states of america

    IMP-ish powerboater

    Raw water cooled chevy in a recreational boat lasts 5-10 seasons in salt before the block is a rust bucket instead of 10-20 in fresh water. Water pump, steering heat exchanger, and manifolds die before the block.
     
  10. lilrobobx
    Joined: Aug 2011
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    Location: Hope Mills, NC

    lilrobobx Junior Member

    i bought marine head gaskets...they are NOT stainless! They are FEL PRO MARINE
     
  11. lilrobobx
    Joined: Aug 2011
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    Location: Hope Mills, NC

    lilrobobx Junior Member

    Im not saying that none of them are but i took apart a MCM 4.3l, they were not stainless and i ordered new gaskets, they also were not stainless...so where do you get stainless 4.3l head gaskets?
     
  12. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    the depending on the gasket style the felpro have stainless fire ring hence they are more expensive than an auto one.
    The salesman should have known this
    Clearly when they are shim gaskets they are easy to indentify but if composite ones its harder so hence I mentioned prior leave them outside and one will rust and the other wont.
    I would say that probably half the replacement head gaskets I did over 15 years on sea water cooled engines were from people that used automotive head gaskets and they will eat out in a couple of months.

    http://www.marinepartssource.com/ne...EL-PRO&mfgno=17010&desc=GM V6 262 Head Gasket
    GM V6 262 Head Gasket
    FEL-PRO 17010

    Your Price: $44.26


    GM V6 262 Head Gasket
    Fits GM 262 cu. in. 4.3L V6 engines
    Sold individually 2 required per engine
    Marine grade
    Gasket core and combustion armor made of 300 series stainless steel, resists rust and corrosion in salt and fresh water
    ****
     
  13. Frosty

    Frosty Previous Member

    Why do you need a stainless fire ring. You don't get sea water in the cylinder.

    A shim gasket should not be fitted dry anyway. I use shilac or even grease (not silicone ****). so it would be sealed on the dozen or so holes passing water.

    I would be more worried about the water pump.
     
  14. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    It eats through from the water side via the gasket. Seen it dozens of times
    felpros were the worst for it.

    How do you seal the edge of the gasket that is in the water passage??

    Yes the water pump certainly needs to be a marine one for seawater
     

  15. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    I wish everybody would use stainless fire rings for both cars and boat engines. Not because it makes sense but I have a substantial amount of money invested in stainless steel industry stock and am presently loosing my savings faster than I can count.

    About head gaskets:
    The evil thing seawater does to all but the most expensive metals is corrode them. But any oxide takes more space than the metal itself, so the corrosion actually improves the sealing quality instead of weakening it.
    That being said, the fact remains that seawater does not only eat gaskets, it digests grey cast engine blocks and cylinder heads just as well. So it should not be allowed near your engine at all. With fresh water cooling the engine lives longer and uses far less fuel because it can be allowed to operate at higher temperatures.

    All you need it a heat exchanger (with lots of stainless steel), some hoses and a small raw water pump. And a stainless exhaust manifold of course!
     
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