cracked motor block

[katbird]

Hello all<br />I have a 1989 Maxum with a 305 c.i. engine. this boat was given to me by a friend. the motor runs fine and idles great. but it has a crack in the side of the block about 4" long where water was left in the engine in the winter. has anyone tried JB Weld to fix a problem like this. i'm trying to fix it without pulling the motor to weld it. this motor only has 118 hours on it and it still looks new.<br />thanks for any input.

 

[rodbolt]

Re: cracked motor block

hello<br /> if that is the only crack and its leaking only to the outside and the manifolds and risers did not crack as well its an easy patch. grind a groove along the crack. drill a 1/8th hole at each end and use JB weld or marine tech or red hand. many an engine has been patched like that. sometimes ya get lucky and it only cracks on the block sides.<br /> good luck and keep posting<br /> PS this repair may only last a few years so watch it.

 

[Bondo]

Re: cracked motor block

Ayah......<br />What rodbolt says.......<br />Other areas that SBCs crack are inside the lifter valley,+ you might want to check All the core plugs(freeze plugs).......<br />I'd find it hard to believe that 1 or more core plugs haven't been dislodged........<br /><br />BTW,<br />Welding is Rarely a viable solution..... By the time you get it where it Can be welded, you're better off Replacing the Block........

 

[deputydawg]

Re: cracked motor block

Try what Rodbolt says. The reason to grind a groove along the crack is give more surface area for the epoxy. By making a valley along the crack and sloping the sides into a V, this is done. Drilling the holes will give the crack a stopping point.<br />After this run it to see if there is any water intrusion into the cylinders or oil. If not you should be good to go. If this doesn't work, your not out a whole lot. Like Bondo says by the time you pull the engine and strip it down to weld it, you just as well get a new block. <br />Maybe check with your welding shop and see, they may be able to weld it in place without removing the engine depending on where the crack is.

 

[achris]

Re: cracked motor block

I've seem a techique called 'stitching' used. Once the area is cleaned up a series of small holes is drilled and steel plugs are driven in and then peened over at the top (much like cherry rivets). I had an old 165 block fixed like this and it worked for years.<br /><br />Chris.............

 

[Bondo]

Re: cracked motor block

I've seem a techique called 'stitching' used.

I've seen this done, But with a slightly different Twist............. <br />The holes are threaded with a tap that has under-cut threads...<br />Then tapered screws are installed..... Each 1 Intruding on it's neighbor..... Then ground, or machined flat.....<br /><br />If we were talking about a "Rare Casting"...... Maybe..........<br /><br />But, A SBC Block is Cheaper........

 

[Dunaruna]

Re: cracked motor block

I've used 'Goss chem-i-weld' with great success but it only works in a closed system. The manufacturer goes to great lengths to say that its a short term fix only but I've run it in engines for years without problems. I've only used it for minor cracks though - may not work on a 4" crack. <br /><br />Aldo

 

[waterone1@aol.com]

Re: cracked motor block

It's almost winter, this is an economical engine to put together, wouldn't you rather have the peice of mind next spring that the engine is 100% and not likely to fail ? Whatever you decide to do, please be safe and cautious if you plan on doing any grinding, welding, etc. in an engine compartment next to the gas tank,batteries, etc.

 

[Don S]

Re: cracked motor block

So, let me get this straight. You want to use some wonder mud on a known cracked engine block so you can go boating for fun and enjoyment on the cheap, while hoping some good samaritan will tow your sorry butt back to the dock, which will ruin part of their boating time, because you are too tight too fix it the right way. Is that it???<br />Boats are not some old junk car you can park on the side of the road and walk home from when it breaks down you know. And usually things like that will last until the most dangerous time to go bad, such as bad weather, medical problem, etc.

 

[bajuski]

Re: cracked motor block

Ron,<br />Don't be afraid to try the JB Weld. I bought a boat that had an 8 inch nasty looking gash from freezing but it didn't leak as much as you would think. The guy used it as it was for 2 years and he would just bilge the water. As long as you're not getting water in the oil and not fouling plugs you should be ok.<br />I cleaned the crack with a wire brush and used the JB Weld that is 2 part epoxy that you knead in your hand.It is easier to apply, it won't run. I worked as much as I could into the crack and overlapped about 1/2 inch on each side of the crack. It's been on for 3 1/2 years and still no leaks. Autozone carries the epoxy. Engine water leak on a boat is a little different than a car because you have an endless supply of coolant.

 

[katbird]

Re: cracked motor block

Thanks for all the input . like I say the motor runs great and not much water leaks out of the block even after the engine heats up.i've done a lot of welding in my time and welding cast is harder than people think. you have to preheat the metal to a dark cherry red then weld and then cover with a insulated blanket to cool very slowly. I also think the JB Weld will work .I've even thought about drilling and tapping small holes and fabricate a small plate with a rubber gasket to fit over the crack. anyway i have all winter to decide. im also ripping out the floor which is soft and i dread getting to that part. <br />thanks again .

 

[KaGee]

Re: cracked motor block

Don..<br /><br />Ya never beat around the bush... and that's what I like about your posts.

 

[katbird]

Re: cracked motor block

I bet Don walks around with a black eye and missing half his teeth with his insults. face to face men dont talk to me like that.

 

[Don S]

Re: cracked motor block

Sorry Ron, you mean face to face men can't tell you the truth without getting beat up? Guess that says a lot about your character doesn't it.

 

[akriverrat]

Re: cracked motor block

don, most of the members of this forum are never out of sight of another boater. most of them think 50 degree water is cold. most of them don,t have heaters and/or windshield defrosters in their boats. and for most a beach is sand, not solid sharp rock. they don,t know where you,re coming from. they are the same people who, last summer' asked "how high above sea level are we?" and "do you accept american money?" they think seattle gets a lot of rain! you won,t win this one.

 

[katbird]

Re: cracked motor block

Dons just being out of touch with other boaters. All he knows is hear say from other boaters and I dont pay any attention to his arrogant answers. He offers no help just like in my post ,the other guys have tried it before and that was what I was looking for. i've tried it on car engines and it worked and was just looking for someone else that tried it with marine engines. Thats one reason I like this boat because i've rebuilt engines all my life and can tell anything just by listening to the motor. I can rebuild a 350 ci blind folded cause i've done it so many times.I guess that you have to live in Alaska to get to Dons level.AND I will JB Weld it if I can. As for as changing blocks now that would be a mistake.To take another crank out and put it into a different block and different pistons in a different block without replacing all new bearings and having everything checked with a micrometer like Don wanted .Now that would be a mess when the motor blew in case of an emergency.Well anyway I appreciate all of the input on my motor block and I will use my air file and gring a V in the block and JB Weld it or should I say WONDER MUD. <br />Thanks Guys

 

[tommays]

Re: cracked motor block

i think that your leak will be fixed but i just mention that even here on long island were its pretty mellow for most of the season we get at least 4 to 6 break downs every season that end in somebody dead usally in one the ocean inlets were the boat ends up capsized after it fails<br /><br />tommays

 

[deputydawg]

Re: cracked motor block

Normally I would say never ever JB weld a block. It might work, migh not. But in this case the cooling circuit is not under high pressure like a car is. Heat might break down the JB weld.<br />I too find Don s a little abrasive at times, but I see where he is coming from. He probably does not boat on lakes like I do. Here there is no salt water, it is all old sand pits or flood control dams. The marina where I go boating has a tow boat in the water at all times, and will be out within 20 minutes to pull someone in. They carry cell phones on their boat so we can always call them. The cost of the tow is 15 dollars unless you are broke, then it is free will donations. He is also a professional marine mechanic the way it sounds. Those guys never believe in a cheap easy fix no matter how good it turns out. I know, I used to be one for Ford.<br />I will say thought that he and many others here know their stuff! Before I got my manuel I learned more than I could ever say just by asking here!