So I moved from the bay area to Pittsburgh (1st mistake) for school. The snow/salt/potholes have not been nice to my 06STI with an ecutek, gruppe-s unequal length manifold and borla hush exhaust.

The flange connected to the up pipe broke totally away from the manifold at the collector weld (dissimilar metals, different expansion, and corrosion bad threesome).

After JB weld failed I had the OEM manifold put on so I could try to have the gruppe-S one welded or try JB weld again. I reset the ECU by pulling the battery/discharging the capacitors and then took it out for a drive after letting it idle for a bit.

It makes about the same amount of boost but now there is a whistle when vacuum is positive that increases in volume as more boost is built. It does not sound like the previous exhaust leak so I am guessing this is the excess boost being purged.

Does this sound feasible? Any other sugestions taking note of the fact I'm a broke student?

John

 

I got a set of gaskets from the subaru dealer. A local muffler shop welded the flange back on and installed it. All seems good.

 

Here is a pic of the flange with a scale

 

What exactly is your question?

 

You seriously tried to JB weld that flange back on? JB weld is just a epoxy resin. And your saying the flange and piping are dissimilar metals? Do you know what type of metals they are (304/316 SS, CS, MS?). I wouldn't think that a header like Gruppe-S would not have anything above or below 304SS and you would think they would use 304 throughout the flanges and piping. I could be wrong but I definitely don't see them having dissimilar metals on a flange to pipe. The welds on the other hand could have been welded with the wrong filler metal, or wrong preparation and that would cause those welds to crack and many other factors but it seems to be a trend with the Gruppe-S manifolds.

 

From the pictures, it looks like the flange was cut clean. If a weld cracks it doesn't make a clean break.....

But regardless of that, it sounds like the fillet didn't penetrate enough into the collector flange, and the heat/stress was too much for it to hold.

I doubt that the flange and pipe are different metals, and if they are it's 304 stainless pipe and a mild steel flange.

If they used ER70s filler wire welding mild steel on stainless, it would look like crap and likely crack. If they used ER308 filler wire welding stainless on mild steel, it would look ok and be kosher.

I hope the shop that welded the flange back didn't just wire feed it can call it good.

 

you should take it to your local exhaust shop and have them clean it up and weld it back together. should be like 20 bucks since its only a small project

 

Edited because everyone thinks my replies are a type of trolling!