Boat motor pics....I found what killed it

[Nitrousbird]

We pulled my boat motor apart today. Yeah, she needs rebuilt. When it died, it was low on oil pressure, started knocking, and smoke started coming out of the carb. It's a 3.0L Mercrusier = Inline 4, boat only GM block, pushrod motor.

 

Here is the #3 piston:

http://www.cofba.org/users/nitrousbird/Boat/Motor/Damaged%20Piston%20close.JPG

 

There is a complete hole in it at the very edge....explains the smoke. There is also a chip of the piston skirt missing too.

 

Here is something I found weird on the crank:

http://www.cofba.org/users/nitrousbird/Boat/Motor/Bad%20Crank%20Machining.JPG

Looks like whenever they were balancing the crank, they didn't get the hole straight, going through the side of it. Well, I was able to flake metal off of that crack.....not good.

Found a big piece of casting flash on it as well.

 

But I do like the gear drive setup it comes w/:

http://www.cofba.org/users/nitrousbird/Boat/Motor/Gear%20drive%20setup.JPG

That's a pretty cool setup. The cam gear is some composite material, probably to keep things quiet in there. I wasn't expecting to see anything like that; does make it easier to disassemble.

 

Couple others pics

 

The cylinders wall all look good, found no water in the oil. All of the bearings looked good too; small hot spot on one of the rod bearings, but nothing to worry about. Of course it will get all new bearings, new pistons, new rods, probably new crank. Need to get a valve job on the head too, as chunk of the damaged piston hit the valves and damaged them. The #4 piston showed a small amount of damage as well.

[Dave1647545494]

probably shares parts with the 2.5 iron duke car engine it uses the same kind of gear drive might be worth checking to see if any of the parts interchange

[Guest boostedmx6]

you might find that unless the still make parts it would be cheaper to small block it nd in the end be more fun

[Nitrousbird]

A small block in my boat = death. Even if I hacked the engine bay up enough to fit one, the weight would kill the balance of the boat, and my outdrive wouldn't take that kind of power. I've have to upgrade to the Bravo series....very expensive to do.

 

The only upgrade motor that would make any sense on my boat would be a 4.3L. The only problem is the cost of converting the 4.3L I have here would be more than just rebuilding my current motor.

 

4.3L exhaust manifolds alone would cost me about $600. Gotta do custom motor mount, most likely different bellhousing, flywheel, starter, alternator, convert boat to having an electric fuel pump or convert motor to a carb setup w/ mechanical pump, flame arrestor, exhaust riser, and some other stuff I probably don't know about. Boat-specific items are always more expensive than comparable automotive items too. The SBC kits (haven't seen a 4.3L kit) to convert an automotive engine for boating use sell for about $1800.