Welding Tips and Tricks

Hey all, first time poster here. 5 year welder/fabricator. All self taught. Had a project come to me, it's an exhaust manifold, constructed of cast stainless steel. I've attempted twice now to weld a crack shut. I've cleaned "v"d, wire brushed it. The only thing I have not done is preheat the manifold as a whole. I did however run a low heat using the torch as just that surrounding the area of my weld a few inches. It's always cracks, or even worse it blows out. A pocket of something, craps it's way up the tungsten. Heat us my next thing. What I'm wondering is would welding this on A/C work? And can I still use stainless or a mild steel filler? Or any other useful advice from those with more torch time than I've got haha.

Thanks in advance

89fizzer wrote:Hey all, first time poster here. 5 year welder/fabricator. All self taught. Had a project come to me, it's an exhaust manifold, constructed of cast stainless steel. I've attempted twice now to weld a crack shut. I've cleaned "v"d, wire brushed it. The only thing I have not done is preheat the manifold as a whole. I did however run a low heat using the torch as just that surrounding the area of my weld a few inches. It's always cracks, or even worse it blows out. A pocket of something, craps it's way up the tungsten. Heat us my next thing. What I'm wondering is would welding this on A/C work? And can I still use stainless or a mild steel filler? Or any other useful advice from those with more torch time than I've got haha.

Thanks in advance

I turn down any cast repairs for the reasons you're reporting. Some people think that if you try to repair it and make it worse, you owe them a new part. You never said what filler you were using. 309L is what you should use.

89fizzer wrote:Hey all, first time poster here. 5 year welder/fabricator. All self taught. Had a project come to me, it's an exhaust manifold, constructed of cast stainless steel. I've attempted twice now to weld a crack shut. I've cleaned "v"d, wire brushed it. The only thing I have not done is preheat the manifold as a whole. I did however run a low heat using the torch as just that surrounding the area of my weld a few inches. It's always cracks, or even worse it blows out. A pocket of something, craps it's way up the tungsten. Heat us my next thing. What I'm wondering is would welding this on A/C work? And can I still use stainless or a mild steel filler? Or any other useful advice from those with more torch time than I've got haha.

Thanks in advance

Are you sure this is a stainless casting? I welded quite a few stainless castings and never have had one crack. Have you tried drilling the very ends of the cracks? You should not have to preheat stainless.
Sometimes you will run into sand pockets in casting, the only thing you can do with those is grind them out and re weld. Never use mild steel on stainless of any kind. You could possibly try 309 or 312, these have better elongation than 308, I would recommend drilling the ends of the cracks re v grooving and weld it up. Do you have a picture?

I'll second the 312. It'll give you a bit more wiggle room on unknown material. Supermissile Weld or another maintenance rod might be even better though. For any of those, if it isn't actually cast stainless and is something like nickel resist, you'll be much closer to the right fill composition.

You said you were getting cracking but where? Posting a picture would probably help btw. If it is just propagation of the existing crack then you need to follow ajlskater1's advice and drill the ends of the crack out. Usually with a bit width the thickness of the casting. It is pretty much the only way to stop a crack from propagating. You probably don't want to preheat but you may see some benefit in baking the entire piece and letting it cool slowly to burn off all the volatile crap. Solvent alone will never do it. Lastly, if it really is stainless, you need to be pretty aware of the distortion risks. If you can bolt it to something to keep it in line while you weld, you'll be better off. Also you might want to do short stretches of welding in and out fast and let it cool completely between passes. Back stitching after it is tacked up may be a good way to go.

-Sandow

I'll snap a picture of it when I get out to the shop today. It's stainless rod I've been using,don't remember the number though. As far as cracking goes, and drilling the end. Unfortunately that's almost an impossibility for the location of the crack. I "v"d with a hand file as deep as I could go, never did break through to the other side and i was at least 1/8" deep. The spot that I got a good cut into welded much better and cleaner until I touched the edge where all the oxides were, then it all went to crap. Sand pockets you say? That would make alot of sense.

can you get a die grinder like a Foredom tool in
there? if so make a divot at the cracks end.
might help.

Difficult to get that to show up in a pic. I know the weld looks atrocious. Believe me, that's not an example of my norm haha.

There's a shot from the other side. The filler wire is 308.

Is manifold magnetic?
(it looks like cast iron)

I would definitely drill the ends of the cracks before welding. Cracks tend to continue unless you drill the ends. If you're sure it's stainless that should be all you have to do and groove it out. Check to see if it's magnetic and also do a spark test if it is magnetic to figure a rough idea of how much carbon it has.

It is magnetic. Not as magnetic as say.. my weld table. A magnet takes more force to pull away from the table than the manifold.

It may be cast iron, but damn. I've welded cast iron before, they were stainless flange to cast iron though. In which case I just walked the clean stainless into my prepped cast iron. Which was a good valley and grinding away oxide metal about a half inch around it. And I've never had this much of an issue.

Is it just because it's a crack? On a piece of metal that has probably seen 600+ degrees on a daily basis? Heated and hardened?

What's the mainfold go on? 600 can be at idle. 1500 at peak boost.

If it is stainless, I think you should dig out the previous weld and crack with a burr and fill it with 309 or 312.
If there is a question whether it is staino or cast iron, you can always use Jody's hardness test by speed tacking an edge and filing it for identification.

Bsmith wrote:What's the mainfold go on? 600 can be at idle. 1500 at peak boost.

I believe a dodge neon? But don't quote me. Lol. You get what I'm getting at though? 1500 degreed for how long? Cooled, cycled like this how many times? Has to have an effect on the weld I feel.

89fizzer wrote:

Bsmith wrote:What's the mainfold go on? 600 can be at idle. 1500 at peak boost.

I believe a dodge neon? But don't quote me. Lol. You get what I'm getting at though? 1500 degreed for how long? Cooled, cycled like this how many times? Has to have an effect on the weld I feel.

13-14 seconds or more. That thing could cruise around 700-1000* depending on what charger it has. Some engines produce 2000* egts. Not sure if the neon does though

That looks like a SRT-4 Neon manifold. Will be cast steel. they are cheep to replace. I have a new one sitting in my shop missing the turbo. One thing I do is use arc welding rods when tig welding. I take the coating off and weld useing it for filler.

Yeah I was gonna ask how much your are charging him because a new one is 100.

If a neon saw 2000 degree EGT it would melt the pistons away...1700 is very high, I say norm around 600-700, on peak boost maybe 1500..truly over 1200EGT and you have to be careful.

Like others, if that is a $100 part it truly isn't worth fixing. Id also use 309 or 312...or something with more nickel in it.