boat motor block craced just below the heads on both sides?!

[aajay]

so i built a 350 .060 over for my boat a few months back (before winter). i have never had it to the lake yet, i broke it in just after i put the motor in. it has an open cooling system, i had the out drive in a huge bucket of water to run water through the cooling system while i broke it in. i just started working on the boat again now that its warm out, and i come to find out that one of the freeze plugs came out and i looked closer and the block is cracked on both sides. can anyone explain how this might have happened? i live in tucson arizona, it does get cold here but how do people in like michigan or colder places do it?!? i understand that its a freeze crack but why? its an open cooling system, doesnt the water have somewhere to go??

[birkey]

You are a rascal

[nascarfan7]

Once it starts freezing, the water trapped in the block actually has no place to go but expand in all the coolant passages. Up here in the north, drain and refill with antifreeze is the norm open or closed system. That includes all systems (water, potty, engine, ect.)

[topfuelrocket]

I replace aprox 10 to 15 marine engines a year, just from new boat owners, that have never been told that yes you have to winterize your boat.
then there are the guys that do drain there blocks but not all the water comes out so they reinstall the block drain plug & it cracks during winter
Before installing the drain plug you should flush out the block water jackets, alot of the time in a open cooling system sand can block off the drain passage and keep the water traped

[rfoll]

You might see my post "Another cracked block" from January. Looks familiar.

[wyrmrider]

time to practice stitch repair

[speedymatt]

time to practice stitch repair

better check the lifter valley too. chances are it is cracked in there too, having a machine shop in Ontario I see lots of it.

[bubbabbc]

time to practice stitch repair

Don't waste your time and money attempting to stitch repair a 350 block. Replace the block.

[rfoll]

I had very special, (for me), circumstances to do the lock n stitch repair. It worked fine and saved me a lot of time and money, but it still cost me about $200. The stitch pins are about $10 per inch of crack and you hope you don't break any of the custom tooling before you finish.

[Racing68]

time to practice stitch repair

better check the lifter valley too. chances are it is cracked in there too, having a machine shop in Ontario I see lots of it.

Check the heads and exhaust manifolds also if they are the wet type.

[rfoll]

I worked on a Chevy 350 boat motor a ferw years ago that had cracked the manifolds and the block. The owner had applied some kind of white sealer to the exterior surfaces and put the boat back in the water. When I tore it down it was full of a thick mixture of light brown sticky goo all the way up to the underside of the intake manifold. Nearly 10 gallons of the stuff. The block had split wide open right down the inner row of bolt and cooling holes next to the lifter valley. Curiously enough, the heads were fine.

[af2]

I worked on a Chevy 350 boat motor a ferw years ago that had cracked the manifolds and the block. The owner had applied some kind of white sealer to the exterior surfaces and put the boat back in the water. When I tore it down it was full of a thick mixture of light brown sticky goo all the way up to the underside of the intake manifold. Nearly 10 gallons of the stuff. The block had split wide open right down the inner row of bolt and cooling holes next to the lifter valley. Curiously enough, the heads were fine.

Bath and tub sealer???

[rfoll]

I am pretty sure that's what it was. It didn't leak on the outside nor on the cracked exhaust, but it sure filled up with rivervwater. ir must have been coming out of the valve cover vents.

[jake197000]

replace the block.

[BCjohnny]

Seven years old .... lol

Perhaps with all this AGW it's not an issue any more ?