Welding a 470 block

[lawns123]

One of my 470s has a crack in the block around the #1 piston sleeve. I would like to know if I take the sleeve out, weld the crack, rebore the cylinder and sleeve it, is there a chance that the weld will not work. We just bought this 26' Sea Ray used. I was told from some mechanics that the block was scrap, and a welder friend said it could be welded. Dont know what to do and dont want to spend $3800 on a new one.

 

[Wart T]

Re: Welding a 470 block

So what have you got to lose? Weld it and see what happens. If it doesnt work you're out the cost of parts and welding AND the cost of another engine. That's the worst case scenario. Is that something you can handle? It's really up to you if you want to try it. If the welder believes he can fix it well I suppose he can. If it is a water jacket that is cracked, forget it.<br />I have never had a block welded that belonged to a customer. That's just asking for trouble. As a guy who's seen it all I advise not to repair it. BUT I have seen guys running blocks that were repaired with no apparent ill effects.

 

[DHPMARINE]

Re: Welding a 470 block

dave and dd..... I've seen these cracks before,if we are talking the same thing.If we are looking at the cylinder,with the head off...is the aluminum cracked as well as the steel surface the piston rings scuff against?I am resonably sure the steel liner is cast in as the block is made.<br />Which makes it not rebuild/replace -able<br />DHP

 

[whickety1]

Re: Welding a 470 block

I've just done a little research on welding cast iron, and founf that it can't really be done unless it is furnace heated to the right temp.<br />When a crack is welded without heating it up first, you will just make the crack bigger, and <br />make the material hard and brittle.<br />I just repaired 2 cracked cast iron water cooled exhaust manifolds with materials from a company called Lock N Stitch. <br />They have a number of types of specialized pins<br />that pull a crack back together, and seal it. <br />It can then be ground/machined down flat.<br />Check them out....Gary will send you a video instruction, and some examples. and is great to deal with. <br />BTW I took my 4.3 out on the lake last night for the first time, and the manifold performed like new. <br />-Whickety

 

[lawns123]

Re: Welding a 470 block

The steel cylinder is not cracked, just the aluminum. It actually looks like they tried to short fix the problem by only welding the top of the crack not the whole thing. The head gasket ring was still intact, It looks like the aluminum pulled away from the steel cylinder. You can actually put a small fingernail between the two. Thanks for the quik replys its much appreciated.