Welding exhuast manifold

[vin1489]

I need to weld up my drivers side factory exhuast manifold on my GN, same place were they all crack. I have a mig, but a friend told me that it has to be welded with stainless steel rod? I thought I would see what everyone else has done before I get started on it?

 

[Blazer406]

To weld it correctly.... you need a stainless filler.... back purge the manifold with nitrogen.... and TIG weld it.

However..... I cut me a small gusset to go inbetween #3 and #5 out of mild steel.... and welded the crack up and installed the gusset and welded it up with mild steel wire on a mig. It seems to be holding.....

FWIW... I also think the manifold is made of 400 series stainless...... like 409? Which is kinda oddball...

 

[87GNTTOP]

Welding

Just did mine. First step. Media blast header and especially the area of the weld.:wink:

You could Mig it. BUT THE CORRECT way is to TIG it. Give it a nice strong TIG weld over the crack.

For cosemetics, I then coated it with CAST BLAST. Came it out real nice and NO LEAKKS!

 

[turbo nasty]

FWIW I just tried mine and they were only welded once before. During attempted tig this time the metal kept spider cracking out from the weld area down in the y connection.

Everything was cleaned and stress relieved prior to. I said screw it and got the TA headers.

More than anything due to the fact the stock headers are going to crack again and the metal is heat cycle fatigued so bad.
I called several vendors about this and the bottom line was it may hold a month or 3 years but the metal is tired. TIG being the preffered method

Food for thought.

Good luck no matter what u do.

 

[phillyturbosix]

I had my mech make a bridge for that pos header! Gives it some much needed support! 2 years and looks like I put it on yesterday!

and all done...

 

[turbofabricator]

Your MIG welder will work just FINE. The manifold is made out of 509 stainless and will weld with mild steel wire just fine. I have even welded them with a gas welder before and it probably lasted longer than TIG welding them. The only way to keep it from cracking is to install a flex joint in the cross-over tube. Installing a gusset will just move the cracks to the edge of the gusset. The header is a poor desgn, and NOTHING will completely cease cracking. Even a header made out of Inconel (un-obtainium) will eventually crack if you are making good power. TIG welding the crack is better and if you back purge, use Argon 100%. Grinding all the surface imperfections works better than media blasting. The media can create more problems than it solves. (Carbide media is great though) Bolt the manifold to a cylinder head before you weld it. The pre-load will help prevent cracking.

 

[GNsnake]

Hey turbofabricator, did you mean 409 stainless? 500 series stainless steels are chrome alloys, not something you'd use make an exhaust system. Anyway 309 works great on 409 stainless also.

Chris

 

[87GNTTOP]

I guess I repaired my header all wrong? But that "509" stainless is really hoding up!

 

[turbofabricator]

Hey turbofabricator, did you mean 409 stainless? 500 series stainless steels are chrome alloys, not something you'd use make an exhaust system. Anyway 309 works great on 409 stainless also.

Chris

Yep........fingers working faster than my brain. (not too hard to do though):biggrin:

 

[GNsnake]

No disrespect man. I weld 409 and 410 stainless daily, just wanted to chime in with the 309 filler for the 409 stainless. A 70-S6 carbon steel mig wire will work fine too.

Chris