My friend has an inivida exhaust system on his sti. The up pipe section keeps cracking. The first time it cracked he brought it to me to fix it and now it cracked again. anyone know why it keeps cracking? is it my welding or is it the material, such as the metal being a low grade type? Its been awhile since i welded and just need some input on how to go about this. I am thinking about grinding the welds down completely and rewelding it, but do i have to grind the whole weld down or just the section where it cracked? There is no flex section in this exhaust system, so i am thinking that having one will help reduce alot of the stress for this uppipe.




thanks,
Brent

 

Cut off the flange/pipe, and weld on a brand new flange and piece of pipe.

 

I work on primarily Subarus, and I can tell you that almost all of the aftermarket uppipes out there are prone to cracking. You should replace it with a good piece that has a flex in it, like the GrimmSpeed one. You may notice on install that it doesn't line up perfectly with the lower manifold piece as well once the two brackets on the top are bolted in.

 

yeah i can try that, not sure if my friend is wanting to spend money on materials, ill have to ask.

here are some update pictures i took after wire wheeling it.






now this isnt a crack, its an indention from something. thought it was at first when it was dirty. hard to take good picture of it. Thought it could still lead to cracking maybe i guess.

 

thanks for saying that, makes me feel better about my welding, hehe. I have no idea about how it lines up. My friend took it off and brought this to me. However i did tell him in the past that he should get a flex pipe, but i guess he never did.

edit: When he first brought me this up pipe when it crack before, only one side cracked. However he wanted me to reweld the other side, but i told him i dont think it should be done, but he still wanted me to do it, and i guess thats why that one side cracked.

 

update pictures again.

whats marked are the only problems with this side


This is the other side with the markings on it.


here is the inside of this side of the pipe crack.

again, the outside.

 

You should really just jig it up and cut out a section of that tube and replace it. Those cracks will just keep coming back if you try to patch it up. I would surface the back of the flange on a mill or sander and try to replace at least an inch of the tube. Downest is right, it's a spot that has a lot of mechanical and thermal stress on it. I have insalled a ton of subaru exhaust parts too and they often don't fit correctly. Make sure your friend is using the brace back to the engine, like the stock setup had.

 

The only solid uppipe I would use is the factory non-catted one from an 06+ WRX or 04+ STi.

 

thanks for your input.

I do agree with you that what you said is proper, but even if i did all that, isnt it still going to crack? if it really has that much stress in that section, then what he really needs is a flex section in there.

 

I mean his welds look good, I'd imagine he knows what hes doing. you need to completely grind out the crack before you re weld it. If you just go over it, it will crack over and over

 

Well, honestly, the weld looks pulsed over, like it was possibly a bad weld made pretty. It also appears to have been pretty underfilled, as it looks pretty concave versus flat.

Crack repairs aren't that simple either. The repairs I've done, I've drilled the crack ends to absolutely terminate the crack, then use a dremel or other such device to open and bevel it to ensure maximum penetration. I then clean and clean, and clean some more. Then I do a really high fill solid weld starting way before the crack and end way after.

 

more filler, heat, speed. try welding the inside of the pipe as well.