Welding cast iron

[Unclefista]

I need to plug some holes in a cast iron exhaust manifold.

I'm using a Mondeo exhaust manifold on my car and I've removed the air injectors (they pump air into the manifold when the engine is cold to aid combustion and warm the cat) there's 5 of 'em, and I'm now left with some 11mm threaded holes to plug up.

I've tried to buy bolts from my local (usually excellent) Nut and bolt place and they say they're a none-standard thread and they can't get any, I'd like to drill the thread out, bung them up with some steel bar and just plug them with MIG, but I have no idea about welding cast.

Is it possible ? I have a 151te on CO2, does anyone have any ideas ?

I'm a bit stumped, and it'll get a bit hot for Araldite

TIA

 

[morph]

why not drill and tap it out to M12?

 

[Unclefista]

Yeah, I suppose I could, but that'd mean shelling out for a drill and tap, and I already have a welder

Seriously though, if it turns out I can't weld it, I'll probably end up doing what you suggest

 

[weldequip]

Forget the CO2, you'll need pure Argon & MIG brazing wire; all possible & I think there is a section on it in the tutorial section.
weldequip

 

[BillJ]

Forget the CO2, you'll need pure Argon & MIG brazing wire

Might be cheaper to buy a drill and tap?

 

[weldequip]

Might be cheaper to buy a drill and tap?

.

Not a question of price... what's best to do the job properly, a manifold needs to be right.
weldequip

 

[weldequip]

Actually, just read over the thread again & a drill & tap is probably the best option.
weldequip

 

[BillJ]

Not a question of price... what's best to do the job properly, a manifold needs to be right.

Personally, I'd be much happier screwing in plugs made from something ferrous. I don't know what exhaust gas temperatures we're talking about on Unclefista's car but on my cars the manifold can glow quite nicely and I'm not sure how well the rather dissimilar metals would get on under those conditions. They might be fine and I'm no expert welder but I'd consider screwing in plugs the safest option if that's how it was constructed in the first place.


My slightly flippant remark was more to do with the reputed cost of MIG brazing wire and the comparatively low cost of a drill and tap.

 

[weldequip]

It can be obtained on small reels relatively inexpensivly BillJ but I think you may be right with the plug/drill -tap method.
weldequip

 

[BillJ]

It can be obtained on small reels relatively inexpensivly BillJ

Now that's interesting. I might try to find an excuse to try it some day, then

I hope it's easier than aluminium

 

[snowcat]

I would personaly forget useing mig on cast work heres a couple of links to cast welds one by lorenzo one by myself http://www.mig-welding.co.uk/forum/showthread.php?t=1930
http://www.mig-welding.co.uk/forum/showthread.php?t=2021&highlight=cast+manifold

 

[Unclefista]

Right, thanks for the advice chaps, looks like I'll be drilling and tapping heat-cycled cast then, oh joy

Cheers, Tony

 

[andrewg1323]

This EGR Removal i assume? i think people just weld over the holes, theres a guide on www.rs2000-16v.com i thinks

 

[Endacy]

What did you unscrew from the holes? Whatever it was put it back and block THAT up. It might even be plain old steel don't forget.

 

[Lippyp]

Rather than buying a drill and tap why not take it to a local engineering company and get them to do it, should cost beer money to do that. I recently had a place tig weld my ally air con pipe up for a tenner.

 

[aametalmaster]

I would try to drill and tap the manifold or obtain studs to screw in if thats possible.

As far as the SilBronze mig wire i have 40 some pounds of it in .023 and i can't get it to weld cast iron, i think the wire dia is too small even with a little preheat from a torch. .030 or .035 may work better for cast iron. I bought mine for sheetmetal work so the .023 is fine for that...Bob

 

[Unclefista]

What did you unscrew from the holes? Whatever it was put it back and block THAT up. It might even be plain old steel don't forget.

I just love lateral thinking, cheers Endacy

That solution never even crossed my mind, which is why I can only find 4 of the 5 fittings I removed (I might need a trip to the scrappy for the fifth one). They're mild steel hollow bolts, easiest thing in the world to screw in and weld up.

I feel a bit embarassed now

Thanks everyone, many different minds thinking over the same problem solves even the worst of 'em, that's the beauty of forums (and their members obviously ).

 

[Wozzaaah]

Hehe, sometimes we just can't see the woods for the trees!