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Hammerhead Rebuild


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I have an 05 Sunscape with the Hammerhead.  I was having problems with the water pump wobbling and breaking.  Turns out to be a bent crank, so we are looking at a rebuild.  My question to you guys is it worth the extra money to go with marine internal components vs. automotive? (crank, rings, bearings...)

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I was unaware that there was such a thing as a marine crank or rings or bearings.   In general the things that make a marine engine special is the headgaskets, waterpump, alternator, starter, distributor, exhaust manifolds and cam (sort of).  The better quality marine thermostats are brass instead of tin.

And then the blocks should have brass core plugs rather than steel.  

Edited by oldjeep
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6 hours ago, oldjeep said:

I was unaware that there was such a thing as a marine crank or rings or bearings.   In general the things that make a marine engine special is the headgaskets, waterpump, alternator, starter, distributor, exhaust manifolds and cam (sort of).  The better quality marine thermostats are brass instead of tin.

And then the blocks should have brass core plugs rather than steel.  

I wasn’t either.  My mechanic (who isn’t doing the rebuild, but having it done) said mercruiser internals are about twice expensive as getting from a performance supplier like Summit.  He wasn’t aware of any difference but was just trying to determine if worth the extra cash for mercruiser parts.

 

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Way back in my past I was told by a mercruiser tech that they built their own cranks and cams.  I'm also thinking he told me that they have a different firing order, too. It was a long time ago....

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Crank will be a standard automotive unit assuming the engine in question has same rotation as automotive version.  Correct Craft used a reverse rotation engine in the past hence a unique crank and cam.  The camshaft is a specific marine grind in most cases, I recall the Hammerhead using a ZZ4 cam which is an automotive one and easily sourced.  Specifically to your post - crank, bearings, rings are automotive.  Marine head gaskets have stainless firing rings.  Root cause for a bent crank?  Check or replace the harmonic balancer if a question. 

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Michigan boarder
32 minutes ago, Woodski said:

Root cause for a bent crank?  Check or replace the harmonic balancer if a question. 

That was my thought too (the first part).

@SkiingPT my engine was built by an automotive guy that sourced automotive component manufacturers, definitely nothing specific to marine for the short block except for the freeze plugs.

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53 minutes ago, Woodski said:

Crank will be a standard automotive unit assuming the engine in question has same rotation as automotive version.  Correct Craft used a reverse rotation engine in the past hence a unique crank and cam.  The camshaft is a specific marine grind in most cases, I recall the Hammerhead using a ZZ4 cam which is an automotive one and easily sourced.  Specifically to your post - crank, bearings, rings are automotive.  Marine head gaskets have stainless firing rings.  Root cause for a bent crank?  Check or replace the harmonic balancer if a question. 

GM provides (provided) reverse rotation 5.7 long blocks as well.  Pretty standard to run a standard and reverse rotation motor in boats with 2 engines.

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