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Discussion Starter · #1 ·
The weld around my wastegate keeps cracking. I only got maybe 10 passes out it before it cracked again. I had a whole new section tig welded in. Is the wastegate mounted in the wrong location on the outside of the bend, or is it being tigged incorrectly? The other wastegate has never cracked.
 

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Are you the welder? The quality of the weld has room for improvement.

Ignoring the poor quality of the weld, it could be due to an improper filler wire. You could try something like ER70S-6, ER70S-2 or ER80S-D2 might be too brittle. I really think it's the welder though, once a crack starts there's no stopping it. It's sometimes hard to tell but it looks like it's failure due to a poor weld. It shouldn't look sooty and scorched like that.

I feel bad if the welder just generally has shakey hands but it's also a high possibility they just don't have experience with the torch.
 

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Clean it really really well. Till it is like shiny clean. Make a pass with Stainless 309 wire and then make a follow up pass makining a large fillet with some silicone Bronze brazing wire. The silicone bronze will mix with the 309 and soften the weld enough to help aviod or postpone the cracking. I would wonder if your wastegate is to small however.
 

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Not to say that I'm not going to try using silicone bronze but everything I read about it says that it's weak and will cause cracking. Look at that weld on the wastegate flange at the bottom of the pic :(
 

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Discussion Starter · #5 ·
No it was a buddy who welded it up for me. Yeah, the weld didn't look the greatest to me either. I am not sure what rod he used. We also replaced everything in that area last time around.
 

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I doubt it's the rod. They should never crack if the weld was good.

It could be some or all of the following.

Poor shielding
Poor cleaning
Burning & lack of penetration (extremely inconsistent)
Poor post flow over the weld
Quenching the weld, did he spray water on the parts to cool it down??
 

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Discussion Starter · #7 ·
The bottom weld was from who ever fabricated everything originally. The setup has been on the car since 2002. That wastegate is the only one to ever give me any trouble. I have 2 innovative racegates so it should be enough. Thanks for the input. Time to head up to SPD Exhaust again.
 

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Discussion Starter · #8 ·
No, no water to cool it down. It was not back purged (I think thats what you call it).
 

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Stainless cracks like that becuase the material shrinks so much when it cools. the silicone bronze helps that problem by giving it some wiggle room. I have a honda header I had made 6 yrs ago with about 150,000 miles on it and it has never cracked at the silicone bronze weld.

Not to say that I'm not going to try using silicone bronze but everything I read about it says that it's weak and will cause cracking. Look at that weld on the wastegate flange at the bottom of the pic :(
 

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And let's remember that if you are using a wire brush to help clean the base metals, that with stainless and aluminum ( I know it is not what is being welded, just something to remember) use that brush for that metal only, so the brush does not brush in contaminates, which like stated above can kill TIG welds.
 

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JP once you get it all redone again get it tacked then bring it by my shop and I'll finish weld it if you can't get Mr. Zimmy to do it for ya.
 

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Im seeing a few issues with the weld.

1: based on the size of the weld i am going to assume the fit-up was not tight, so the welder (your friend) used filler rod to fill the larger gap.

2: Way to much heat being used which is evident from the grey color of the weld

3: Inconsistent heat. Not exactly an estetic looking weld.

4: If this is stainless, then the fact that it was not back purged is deffinetly going to cause issues.

CraigS
 

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One thing that hasnt been mentioned is the weight of that wastegate. Is it supported else where? Sure the welds are not the best, but when the area gets hot , its already thin there as it comes off the bend.
 

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One thing that hasnt been mentioned is the weight of that wastegate. Is it supported else where? Sure the welds are not the best, but when the area gets hot , its already thin there as it comes off the bend.
In most cases I would agree, but it appears that there is some kind of gusset that is welded in there. right below the bolt.

CraigS
 

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How many times has this material been welded on????????

Stainless work hardens with welding...then it cracks... over and over and over and over.........

It may just be time to have it replaced...you said the other side has never broken....was it ever repaired???????
 

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it breaks because it's not supported and there is no slip joint on it.
this is the support..

slip joint,although it's wrapped and difficult to pick out...
 

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Although the welding could use some improvement, the old innovative race gates are HEAVY. You must support them. If you are dumping the wastegate back into the downpipe you should add a slip fit or flex bellow. That wastegate mounted in that spot will not last with even the best welding, unless you properly support it.
 

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looks like a bad weld on dirty stainless.that thing needs to be spotless and then start welding, it also looks as if the weld is standing ontop of the material and not bonded properly.Aslo if it doesnot have a good gusset, it needs one installed.
 
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