Hey guys, I'm hoping you can shed some light on this issue I'm having.

To make a long story short, we had to salvage a dowel pin from our old 408 iron block to use in our new 418 ls3. In the process of hammering it out of the block, the block cracked and a chunk literally broke off of it. The part of the block that broke is the kickout where the starter bolts up to. It is pretty thick stuff, and I know cast iron is hard to weld properly.

From what I've been told a good stick welder is all that will really work. Is this correct information? What do you guys recommend doing to repair the block? I might try seeing if machine shops in the area can take care of it, but they are all so backed up now its crazy.

Any help/insight/ideas at all will be much appreciated. Thanks!

-Ross

 

It can be done by a good welder with a TIG too...it requires very special attention and some special techniques. I've personally have welded on an axle centersection (cast iron) before and it's holidng up fine in that car despite seeing a lot of abuse...I've seen other welds to cast iron fail as the material cooled from the weld before any stress was put on the part because the person welding it didn't know the proper techniques. Find a very qualified welding shop and they should be able to do it for you.

 

you can weld it with a regular mig welder too, you need to take a torch and get ir real hot...like glowing hot, and then weld it like normal , i dont know how the rest of the block will respond to getting a corner that hot, but ive welded cast several times like this. once you start welding make sure you put some good stuff on it.

 

Thanks for the replies guys. I will have to consult with some welders here locally it seems. I have a 110v MIG and I doubt it has the guts to get this done. I'm just gonna have to bite the bullet and get someone else to do the repair it looks like. If anyone else has any insight to this, keep it going.

Thanks,

Ross

 

You need to heat it up HOT, up to about 1200-1300*. Supposedly your not supposed to get it to 1400 then its very crack prone, but ive heated it up to red hot before with no issues. Then weld it with nickel rod, TIG with multiple small passes. Or Arc weld with the same....nickel rod. Then after you weld it keep heating it and slowly stop heating it, slowly bringing the temp back down. You want it to cool very slow, and all cool at once. If the area around where you welded cools before the weld it will most likely crack. That is why you do it slowly.

 

Here is some good info on cast:
http://www.ehow.com/how_2164565_weld-cast-iron.html

http://www.lincolnelectric.com/knowl...ronpreheat.asp

 

Thanks 94z, good info there. I think I found the Lincoln one in a google search a couple days ago. Being an engine block, I'm thinking the "cool" method is the best option. It would be hard to get the whole block 500+ degrees. I might could get the broken spot that hot, but from what I have been reading, that is not really ideal.

I was able to do some more research today, and found several places where people were talking about using "Certanium 889 SP" welding rods. Apparently these rods are designed specifically for welding cast iron, and they are supposed to work really well on just about any variety of "cast iron". Has anyone had any experience with them?

 

I weld for a living mostly pipeline and oilfield/gasfield stuff, but we do repairs like this weekly. Use a high nickel rod if you can find it where you live. 7018 is what we use for the most part and it seems to work very well on thicker cast iron. You want to heat it until it is about 500 or hotter just don;t let it start melting or sparking then you contaminated the metal and that bad. The block needs to be bare or you will likely mess many things up. Get insulation that is fireproof also. When you are done welding it heat it back up to around 800 and wrap it in the insulation and keep it in a warmer environment if possible such as a garage. When you heat it don't concentrate your heat to much let it heat the area slowly so that it is hot all the way through and not just the surface. Grind the piece so that you can get good penetration. After you make your initial passes grind them down a ways and that will help get the impurity out. When you are welding it, it will weld much different than you are used to. It will kind of sparkle and weld funny, just weld it like you always do. It also depends on the quality of the cast. Anything i can do to help let me know.

 

Thanks for the info cdwood! I'm still not sure if I will weld it myself, mainly because I do not have access to a good stick welder, just MIG. Plus, I would feel better getting someone who is more qualified to do it than me. I just weld from time to time as the need arises. I want this done right and I'm afraid I might mess it up even more if I go off trying to weld it not knowing exactly what I am doing.

 

listen to this guy. i weld for a living too and this cant be explained any better.

 

One word...Preheat.

 

after you preheat and weld it, try to get some lime and sit it in, that will make it cool as slow as you need it to

 

I use lock and stich for cast iron repair on heads and block. It looks factory after the repair and I have only done about 6 blocks though. http://www.locknstitch.com/
There is no heating up of the metal and it is easy to work with.

 

Thanks for all of the input guys, it has been a great help. I am gonna preheat for sure if I end up doing the welding. I might have a line on someone who can do it for me though who has welded cast iron before. The last resort would be welding it myself.