Here's the story:

I've taken the boat out 3 times since I bought it in June. The last time we took it out, we launched it early on Saturday morning. Ran it for about 15 minutes, up to roadrunner for some breakfast. Tried to fire it up after eating and no go. Had to float it back down to emerald cove and load it up. I checked to oil while floating and it was halfway up the dip and a milkshake.

Once we got the boat home did a compression test found #4 & # 6 at 40-45 psi. This is where my Mechanical and engine know-how hits a 50ft wall. Luckily a family friend has been helping me out. We pulled the heads thinking it is a head gasket. Upon inspecting the head gasket it appears that the head gasket was replaced fairly recently (past couple years). We then looked at the cylinder walls on #4 & #6 and they are scored and burnt.  We then looked at the cooling jackets for those cylinders and they were completely clogged with dirt and mud. It looks as though the previous owner had a similar issue and replaced the head gasket without checking the cooling jackets for any debris. Also after inspecting the head there appears to be a hairline fracture on on there as well.

So my dilemma is, do I want to rebuild this block or should I scrap it for a reman engine. This family friend has a distributor account from a company so i would be able to get the long block at cost. From what he has told me the price of the reman long block would be a couple hundred more than paying for the labor to have my old block rebuilt.

I am new boating and as stated before my mechanical ability is fairly limited to basic maintenance. From reading the forums you guys are some of the most knowledgeable experts in the industry. I will post some pics of the carnage tonight, after i go by the garage.

Any questions let me know I will try and answer. Thanks for any help.

454 BBC.

This is a re-post of what I told another boater with a failed engine... You can see the whole thread at the link below.

The problem is that most "crate" engines are automotive engines, with automotive tolerances.  You want an engine built with open cooling system marine tolerances.  I had my machine work done at a small shop in Yucaipa called Johnson's on 10th st.  His shop is well equipped and he knew exactly what I wanted when I told him is was for a jet boat.  It wasn't cheap, but it was reasonable for what I had him do.

For getting the engine out of the boat, find someone with a forklift to help you get it out and into the back of a truck.

Good luck

http://www.socaljetboats.com/engine-mechanical-electrical/i-heard-a-big-deep-heavy-boom-and-then-it-was-done-(454-blown)/msg209410/#msg209410