Tig welding cast iron?

Jason_alex · Sat Mar 15, 2014 7:16 pm

Hey guys I have a few questions about tig welding cast iron. I have seen that it can be done, now my question is how hard is it to do. and can it be done on a cylinder head? I have a 4.0 Jeep I6 head that has a crack that separates oil and coolant. Just to verify this over the valve cover not in the combustion chamber.

Can I get anyone's thoughts on this? Has any one done cylinder head repair with tig or stick? Or am I way off in left field on this one?

Thanks,
Jason

Sat Mar 15, 2014 7:32 pm

Since it's not in the combustion chamber, it's a safer bet to braze it, whether with TIG or oxy/fuel. There's less prep, and less danger of "growing" the crack or having it re-crack as it cools.

There are several here with more experience in brazing on cast than I have, and I'dd defer to them to advise you how to proceed.

Steve S

Jason_alex · Sat Mar 15, 2014 8:16 pm

Good To Know Hope To Find Dome Good Info, I Am Goint To Do A Stroker Build And Dont Want All That Porting To Go To Waist If It Dose Crack.

Superiorwelding · Sat Mar 15, 2014 10:42 pm

Jason,
Yes your cast head can be "repaired" using GTAW method. It is not very hard to do. I have limited experience but have done several rapairs now using silicon bronze as my filler. Here is one part I repaired, you can get my setting from there
http://forum.weldingtipsandtricks.com/v ... f=5&t=4479
One thing I am not sure of right now is if silicon bronze will withstand the temps your head will see. Will look it up soon.
Something I would recommend is first lighting up in your cast part to just head it up and bake off the oil that will be present on it. You can also use a torch as well. Do not melt the base material just hear it up enough to melt the silicon bronze. A picture would help me out better on advising if you need to grind out material as well.
There are other methods to repair your head as well, hopefully someone else will give you other ideas.

Also here is a product that I have not used but looks promising.
http://ezweldtigwire.com/
-Jonathan

Braehill · Sun Mar 16, 2014 1:06 am

Jason,
First thing you might want to think about is the fact that a head for a 4.0 Jeep is very common and readily available without cracks. Used, they are very cheap and I would go that route if I was going to go through porting and relieving a head. Do you really want to spend all the time and money building a stroker and spin a rod bearing because your weld failed?

So the simple answer is yes you can weld it, should you weld it, no.

Just an opinion from a person with 40 years working on cars and trucks, but again, just my opinion.

Len

Jason_alex · Sun Mar 16, 2014 1:22 am

I have 2 of the heads right now, one is good one is bad I plan on porting the good one but if it dose end up cracking and leaking antifreeze into the oil I want to know I at least have a chance at fixing it.

power · Sun Mar 16, 2014 9:32 pm

Jason, I have welded a bunch of cast. I am no expert but have had great luck using this method. After I have prepped everything to be welded. I warm the part up slow by a pan heater or space heater not hot just warm to the touch. I use 3/32 red tung, 20-25 gas psi, gas lense. 309l stainless steel filler take it very slow cast does not like to be rushed.. I posted a pic a week ago on some cast I recently done.

power · Sun Mar 16, 2014 9:37 pm

A picture.

Jason_alex · Sun Mar 16, 2014 9:50 pm

Can I ask why you used stainless rather than nickle?

Arizona SA200 · Mon Mar 17, 2014 7:54 pm

If there is any question as to what the base metal is comprised of 309L is my go to filler. Its very versatile. Welding of cast has been done this way a lot. With your situation i would go with silicon bronze, for two reasons. Oil passage and water jacket temps should not exceed its melting temp and the cleanliness if the material would make it difficult to use 309l. I'm sure you will get other opinions but this is mine.

Superiorwelding · Mon Mar 17, 2014 10:39 pm

Superiorwelding wrote:Jason,
One thing I am not sure of right now is if silicon bronze will withstand the temps your head will see. Will look it up soon.

I looked up the specs for silicon bronze according to Crown. The melting point is 1866* and your coolant should be around 240-250* max of actual temperature. This is assuming that this passage in not very close to the combustion chamber.
I agree that this is probably the best filler for the application for the same reasons that Arizona said.
-Jonathan

Jason_alex · Tue Mar 18, 2014 9:43 am

Sounds great guys I am going to start porting soon, I have heard that bronze dose not bond very well to cast iron, is this a old timer blowing smoke then again he was using brazing.

Alumike · Thu Mar 20, 2014 12:04 am

The first question to ask with any failuer is "why?". I don't remember ever seeing this head crack on top. Only in the chambers and across the deck. Cracking across the top is generally 2 reasons. 1 the head was overheated and warped, putting the top into a tension or stretching condition. 2 is the constant compressing of the valve springs, causing the top of the head to "oil can", causing a fatigue crack. I would not weld on a cast head. I would instead use Lock-n-Stitch. I have used this method to make plenty of this type of repairs. Not on this head, but the 4.0 Fords and 2.5 GMs liked to crack on the top. I would also be sure to have the entire head magna fluxed. If the top is cracked I would bet that there are other cracks. These heads crack so frequently that good used are hard to find. I know of at least 2 companies that make aftermarket castings. I have recommended Lock-n-Stitch before. I do not work for them, but have used their products for 20 years. I know that this method is much better than welding in most cases.

Mike