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Monsoon engine block


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I just found out my engine block has an internal crack in it. I thought it might be just external, but I started the motor and have a milky way Latte where my oil used to be. Looks like I am replacing the block. I have a 98 Sunsetter VLX with the monsoon motor. I only have about 320 hrs on the boat so I am hoping to just replace the block and reuse my existing parts. Anyone have any connections on getting a stock 5.7L block or perhaps a salvageable monsoon motor? All info would be much appreciated as boating season is almost here.

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I'm certain someone will correct me if I'm wrong, but I am sure that a "vortec" 350, as would come from a '96 to 2000 Chevy/GMC pickup, Suburban, etc. would have the same block (and maybe the same heads). You could get a rebuildable core motor from the wrecking yard (or maybe the machine shop that will be doing the work) & use the block & trade the other components for part of the bill. Since this block is "miles & condition unknown", I would have it rebored & buy new pistons to match the new bore size. I would probably have the crank polished/ground & buy new main/rod bearings also. The rest of your boats original components can probably be reused. You might ask the machinist about "freshening up" the heads while they are off, that shouldn't cost very much. Don't let anyone convince you that you have to have "special boat parts", it's just a Chevy engine, however they usually use brass freeze plugs & the head gaskets are sometimes offered in "marine" versions that are made of materials that are a bit more corrosion resistant.

Sorry about your luck & hope your back on the water soon.

Edited by Hman442
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Are you sure it is a crack, and not just a bad head gasket.. it'd do the same thing.

Don't start flailin around on the block, there are lot of blocks out there that are very similar... get in touch with Indmar and ask

... but I'd do some other checking first. A cracked block in unlikely, and relativly rare, unless you had some freezing issue. I vote for bad head gasket, or cracked head.

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Before you do a rebuild, check around for deals on long blocks. As posted above, the block itself is nothing different between the 5.7 vortec chevy truck. The "marinizing" comes in the rebuild kit - gaskets, plugs, etc. Are your heads cracked too? One of mine was. There may be differences in the heads between marine and non-marine, but if I remember right they were the same. But again as posted above, it will be hard to find a good block at a salvage yard that isn't already worn out some. IE, bore job required, and now you are back to not being able to use your internals anymore. I priced out a full rebuild on mine, and then ran across a company called Engines Direct (found them on ebay). I didn't buy off of e-bay, but I called them up and they shipped me a long block (heads included) for less than I could do the rebuild myself considering bore job, new pistons, head replacement, etc. Shipping was $99 unloaded and sitting on my garage floor. Something you might look into before tearing into it yourself. You do have to specify the "marine" version.

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The Monsoon is a GEN 1+ small block Chevy with standard Vortec Heads. It is a cast Iron block with 4-bolt main bearing caps. The Standard GM Vortec engine is a Gen 2 Small block chevy that has a cast iron block with 2 bolt mains.

You should be able to go to a wrecking yard and ask for a 350 chevy with 4 bolt mains and get a rebuildable engine for less than $200. They made these blocks from 1970s to the late 1990s You might have to bore and add new pistons to the block but that will only make it better. If you do the assembly yourself you should spend less than $1500. The vortec heads, intake manifold and injection system will bolt right on.

Strip the engine down and have the block and heads checked for cracks. Someone may be able to weld them if they are in a good spot.. I had a block that had 8 inch cracks in the external water jackets. They were able to stitch them up with set screws. It looked fugly but ran great. Biggrin.gif

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I heard marine heads have different valve seats.

I did lots of research on the head issue because there are two castings out there and I was concerned with the heads I had on both the new long block and the original Indmar engine. I too had heard that marine heads had hardened valve seats. I spoke with two reputable engine suppliers (both supply marine and auto engines) that both told me that all of the vortec heads had hardened seats. I can't verify that personally, but I was never able to come up with any concrete info that there were different heads on a marine vortec. I also did some internal digging at work (GM).

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The Monsoon is a GEN 1+ small block Chevy with standard Vortec Heads. It is a cast Iron block with 4-bolt main bearing caps. The Standard GM Vortec engine is a Gen 2 Small block chevy that has a cast iron block with 2 bolt mains.

Without a doubt my original monsoon was a 2 bolt block, and so was the replacement I put back in.

I dug up my receipt and the total cost for an assembled long block was $1599 shipped. This included the rest of the marine gasket set as well. All I had to do was put the intake, oil pan, and timing cover on (which is supposed to be replaced every time).

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The Monsoon is a GEN 1+ small block Chevy with standard Vortec Heads. It is a cast Iron block with 4-bolt main bearing caps. The Standard GM Vortec engine is a Gen 2 Small block chevy that has a cast iron block with 2 bolt mains.

Without a doubt my original monsoon was a 2 bolt block, and so was the replacement I put back in.

I dug up my receipt and the total cost for an assembled long block was $1599 shipped. This included the rest of the marine gasket set as well. All I had to do was put the intake, oil pan, and timing cover on (which is supposed to be replaced every time).

After 1999 they stopped making the Cast Iron 4 Bolt main Block so later engines are 2 bolt. The Vortec Heads and intake will bolt on to either block. If I was rebuilding I would definitely get a 4-bolt block. If you are going to put the money into machining you might as well start with a strong one Biggrin.gif

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