View Full Version : Cracked Block on 1996 Prostar

05-29-2008, 05:10 PM
I was just curious if anyone knows if there was a common spot on a 1996 Mastercraft Prostar with a GM 5.7L that the block usually cracks? Unfortunately I ran out of time in the fall and talked myself into the fact that my garage really doesn't get that cold... Its a shame because the engine only had 52 Hrs on it. Additionally, does anyone have any recommendations on where to get a new long block? (not rebuilt)

Thanks Shoe...

05-29-2008, 05:29 PM
Sorry to hear the news. That really is a shame with a 52 hour 1996 engine.:eek: My ski buddy thought the same thing about his garage a couple years ago and learned the hard way. Despite the rebuild, his boat has never been quite the same since. Hope yours turns out well and that you get that thing back in the water before sumer is over.:)

05-29-2008, 06:25 PM
Get the specs. from Indmar for the engine you have and check out the local salvage yards.

05-29-2008, 06:39 PM
If a rebuild isn't the same, something wasn't done right, no offense.

Is the crack on the outside, about half way between the head and oil pan? If there's no water in the oil, grind a groove and seal it with Marine Tex to see if it will hold. If it does, run it. If it doesn't, Jasper is one of the companies I have used with excellent results (as in, no problems). The don't just rebuild, they re-manufacture the engines and don't re-use many parts. Also, they have a 3 year- unlimited hours warranty on their marine remans, which is the longest in the business. You can buy a long block, but I would get a short block, instead. Anyway, you can get a motor from GM Performance parts that will equal or exceed what you have but they only have a 12 month warranty and specifically exclude marine use.

Because of the first-hand experience with them, the first call I would make after I found that my motor is toast would be to Jasper.

05-29-2008, 07:14 PM
I would second that recommendation for Jasper.

Don't forget to check them exhaust manifolds! Once in a while they are the only thing that cracks and the block goes undamaged...

Good luck!

05-29-2008, 08:54 PM
There are no leaks that I could see from the outside of the motor. There is water in the oil... Not to sound stupid, but would a cracked exhaust manifold put water into the oil?


05-29-2008, 09:00 PM
Not usually. It is possible that the freeze blew out a gasket but it would require a teardown to find it and clean up the water.

05-29-2008, 11:25 PM
I had a leaking manifold gasket (between the manifold and riser) in another boat that filled up the cylinder thru the exhaust valve. The water then leaked past the rings (?) and ended up in the oil. Fortunately it all ran into the block before I cranked it (or the exhaust valve stayed open while the piston was on the way up), therefore didn't hydrolock and only repair needed was an oil change and a new riser gasket. Lucky me!