95 Nautique Cracked Block

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   First post but have had a lot of luck troubleshooting with help from this site already. A little background: Boat is a 1995 ski Nautique 351w/1:23. Bought the boat not running with a seized motor (winterized and stored for 3 years but couldn’t turn over by hand when I looked at it originally). Over the 4-5 weeks getting it going, I found (mostly thru this site) the boat was originally EFI, and was swapped over to carb at some point before me owning the boat. 
Got the boat running (in driveway) and seemed fine, typical tune up, carb clean, new battery, new plugs etc. was done and everything checked out. Finally got the boat on the water and ran great…cold. Once it warmed up immediate miss/hesitation and I limped it back to the ramp. Got it home, ran it on the hose, and it basically oiled my driveway with the coolant water & oil mixture thru the exhaust. 

Photos to follow, but tear down showed a BURNED head gasket between cyl 2-3, to nothing-non existent missing gasket material and missing 1/8’ firing ring on each cyl…what looks like detonation damage between cylinders 2-3, and a vertical 1’’ crack down cyl 3. Head is also cracked at the mating surface between cylinders 2-3 with same detonation damage…Past the point of machining (obviously). SO, I end up getting a junkyard 351w long block from a ‘97 f250. Start the cleanup & swap over process and the cylinders still have nice cross hatching, stock bore etc..get the desired gt40p heads, and plan to upgrade the intake, which leads me to my question:

Am I crazy/an idiot to not touch this junkyard bottom end or eBay gt40 heads, assemble and just send this thing ? What I mean is NOT having any machine work done to either the heads or block, assemble as-is, and hope for the best. I feel like I know the answer to my question, but that drastically changes this “budget” boat I got myself into. For reference this boat will probably always be a 50 YD beauty, and I’m really on the fence on spending the $$ on a dialed engine. Has anyone not gone the top dog rebuild route and had any success ?

If not, looking for a good machine shop in Mass/NH area. 

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Paulski95 Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: August-09-2022 Location: Mass Status: Offline Points: 3	Post Options Post Reply Quote Paulski95 Report Post Thanks(0) Quote Reply Topic: 95 Nautique Cracked Block Posted: August-10-2022 at 7:16pm
	First post but have had a lot of luck troubleshooting with help from this site already. A little background: Boat is a 1995 ski Nautique 351w/1:23. Bought the boat not running with a seized motor (winterized and stored for 3 years but couldn’t turn over by hand when I looked at it originally). Over the 4-5 weeks getting it going, I found (mostly thru this site) the boat was originally EFI, and was swapped over to carb at some point before me owning the boat. Got the boat running (in driveway) and seemed fine, typical tune up, carb clean, new battery, new plugs etc. was done and everything checked out. Finally got the boat on the water and ran great…cold. Once it warmed up immediate miss/hesitation and I limped it back to the ramp. Got it home, ran it on the hose, and it basically oiled my driveway with the coolant water & oil mixture thru the exhaust. Photos to follow, but tear down showed a BURNED head gasket between cyl 2-3, to nothing-non existent missing gasket material and missing 1/8’ firing ring on each cyl…what looks like detonation damage between cylinders 2-3, and a vertical 1’’ crack down cyl 3. Head is also cracked at the mating surface between cylinders 2-3 with same detonation damage…Past the point of machining (obviously). SO, I end up getting a junkyard 351w long block from a ‘97 f250. Start the cleanup & swap over process and the cylinders still have nice cross hatching, stock bore etc..get the desired gt40p heads, and plan to upgrade the intake, which leads me to my question: Am I crazy/an idiot to not touch this junkyard bottom end or eBay gt40 heads, assemble and just send this thing ? What I mean is NOT having any machine work done to either the heads or block, assemble as-is, and hope for the best. I feel like I know the answer to my question, but that drastically changes this “budget” boat I got myself into. For reference this boat will probably always be a 50 YD beauty, and I’m really on the fence on spending the $$ on a dialed engine. Has anyone not gone the top dog rebuild route and had any success ? If not, looking for a good machine shop in Mass/NH area.

KENO Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11112	Post Options Post Reply Quote KENO Report Post Thanks(0) Quote Reply Posted: August-10-2022 at 8:15pm
	With the word "budget" thrown in there, I don't think you're an idiot or crazy, then again I don't know you either I have an engine that was built about the same as you described that just won't die. Just assemble it carefully, use the original boat oil pan and oil pump pickup and dipstick and transfer your marine parts to the new engine The timing cover is specific to your boat engine so you definitely want to reuse that Maybe put in a new rear main seal. It's a 1 piece and in your case a rear main seal for a 97 F250 will work fine You might want to put brass freeze plugs in the block and the heads, otherwise maybe 10 or 12 years down the road, one may rust out Bad winterization makes me wonder about the condition of your exhaust manifolds, since they can leak water into the engine or leak externally. Could you spend a lot more on the engine? Sure but you have a budget in mind and a plan in your head so I say ..................Go for it

Paulski95 Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: August-09-2022 Location: Mass Status: Offline Points: 3	Post Options Post Reply Quote Paulski95 Report Post Thanks(0) Quote Reply Posted: August-12-2022 at 11:12am
	Thanks. Have most of the marine specific stuff pulled, just need to remove the engine out of the boat. See the block damage and what the boat looked like the day I got it.

95 Nautique Cracked Block

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