Welding tips..need to fix my manifold in a hurry!

[RyanRs]

I have a cheapish Mig gas / gasless welder that i am slowly learning to weld with, however i am still a long way off being a confident 'DIY' welder.
Now, i have an issue with my 304 stainless exhaust manifold constantly cracking. The manifold was made by Rogue years ago and this part is fine -it is however the wastegate takeoff pipe that i made myself that keeps cracking. The metal i have used is also 304 stainless and once i cut it to size/shape, i had it professionally tigged, however, it keeps cracking on the outsides of the welds, mainly where the custom pipe meets the rogue manifold.

I need this sorted before the 4th of sept as im due in for mapping.I dont care if its a bodge as i can sort the issue properly afterwards, i just want the thing sealed up for its tuning session!

I have "repaired" the cracks to the bottom of the pipe and a couple to the top, however after a couple of hours blasting around the crack that was on the top has re-appeared. Luckily i dont need to remove the manifold to weld it up this time as its easily accessible from the top.

Could anyone give me any tips as to how i can sort this crack out with my mig welder, so its good enough for tuning on the 4th? I have a good idea with wire feed speed, voltages etc but i guess its technique that i lack. Would it be a good idea to run the engine for 5 minutes prior to welding so the manifold is hot?

Also, any idea why the 304 tube that i have used is cracking however the 304 manifold is fine?

Thanks for the help!

[Lee8ballauto]

You would be wasting your time with a cheap gas/gas less mig tbh pay someone to do it properly for you or replace the section that's cracking. When you weld it can weaken the metal around it due to the heat that's generated afaik.

[John145]

Go on youtube and just search for mig welding tuition etc. Also note stainless requires a different method than mild steel so ensure you research it properly! Good luck!

[John145]

Don't bother running the engine before welding, and it'd be easier for you to remove the exhaust is possible. Much better than setting fire to yourself welding upside down! (speaking from experience here... although this is welding mild steel and not stainless)

[T.F.S.]

Picture of manifold?

[Nic]

Is the pipe supporting the weight of the wastegate? some pics would help.

[RyanRs]

Na, its not supporting the weight, its braced up also. Its a top mount and the crack is along the top of the wastegate take off pipe so would be easier to leave it on the engine when fixing it as its in a nice position -no upside down welding needed -done that also, not nice! lol.

I think it may be down to fast heat cycling where its effectively a pocket where the gasses build up against the wastegate causing a massive heat build up and then once the WG opens i can only imagine it cools quick quickly? Obv gasses passing through the mani flow straight through the turbo so no buildup until the high end of the rev range..

ill find a pic.

[LimeyMk1]

Can you get gasless welding wire for stainless? I'm not sure if you can.

[RyanRs]

Do you have to use the gas with stainless then? i thought gas was only there to make it easier and give a better weld?!

[bobhatton]

Do you have to use the gas with stainless then? i thought gas was only there to make it easier and give a better weld?!

Yes, it gives it a better weld.

So much metal for sale now comes from China and is crap so the part you added may be this crap metal.

You need the right wire type for the metal you are welding and Argon shielding gas together with a back purge gas or it will crack all the time

[Peter Gidden]

I think it may be down to fast heat cycling where its effectively a pocket where the gasses build up against the wastegate causing a massive heat build up and then once the WG opens i can only imagine it cools quick quickly? Obv gasses passing through the mani flow straight through the turbo so no buildup until the high end of the rev range..

More likely to be crap welding.

[RyanRs]

Pete, true - but it was originally welded up by a professional, the guy is a personal friend of mine and is an experienced metal fabrication welder. All the pieces were tigg'ed and all the welds were very neat and even. Im thinking it may be cheap crap metal as bob says as after all i did source it off ebay.

I am thinking that perhaps the best way to attack this would be to Jig the wastegate v-band flange in place, then cut the old pipework out and weld in fresh new pipe?

[bobhatton]

Pete, true - but it was originally welded up by a professional, the guy is a personal friend of mine and is an experienced metal fabrication welder. All the pieces were tigg'ed and all the welds were very neat and even. Im thinking it may be cheap crap metal as bob says as after all i did source it off ebay.

I am thinking that perhaps the best way to attack this would be to Jig the wastegate v-band flange in place, then cut the old pipework out and weld in fresh new pipe?

Yes, and stop buying things off ebay

[RyanRs]

Pete, true - but it was originally welded up by a professional, the guy is a personal friend of mine and is an experienced metal fabrication welder. All the pieces were tigg'ed and all the welds were very neat and even. Im thinking it may be cheap crap metal as bob says as after all i did source it off ebay.

I am thinking that perhaps the best way to attack this would be to Jig the wastegate v-band flange in place, then cut the old pipework out and weld in fresh new pipe?

Yes, and stop buying things off ebay

Lool but it said 304 and 1.2mm wall thickness or something so i didn't see how i could go wrong?!!

[bobhatton]

Pete, true - but it was originally welded up by a professional, the guy is a personal friend of mine and is an experienced metal fabrication welder. All the pieces were tigg'ed and all the welds were very neat and even. Im thinking it may be cheap crap metal as bob says as after all i did source it off ebay.

I am thinking that perhaps the best way to attack this would be to Jig the wastegate v-band flange in place, then cut the old pipework out and weld in fresh new pipe?

Yes, and stop buying things off ebay

Lool but it said 304 and 1.2mm wall thickness or something so i didn't see how i could go wrong?!!

Now you are going to tell me you got your turbo off ebay too and was only £250.00

[bobhatton]

You need 321 (1.4541) steel and can get it from

Aalco Swanley
Units 6 & 7
The Interchange
Wested Lane
Swanley
Kent
BR8 8TE

Tel: 01322 610900

[RyanRs]

Nooo! My turbo is a genuine 'New' garrett from ATS and sent to FP for the HTA upgrade! I never cheap out on vital parts! Main reason i ordered the tube from ebay was because i was having trouble sourcing pipe from places other than there and also with having to wait 2~3 days at a time from fabricators to reply to emails -usually telling me they do not stock the size tube that i require!

I know 321 is the ideal grade to go for, but will it weld ok to the 304 manifold?

btw, do you happen to know what the inlet flange pipe diameter is of the MV-R tial ? its bigger than the exit pipe..

[bobhatton]

Yes it will weld ok, just use the right filler rod for the 321, but your welder will know that when he does the finel job.

[mk2mattw]

i am a self taught welder-have done loads now including making 2 exhaust systems from scratch-i got no qualifications in it jus practiced....ALOT!haha

Gasless welders are absolitely rubbish tbh,i have a cheap welder (cost £250) most of it is down to the wire feed, i roughened the wire feed wheel so it bites into th wire so it doesnt slip at all.(welds better than my friends one that cost twice the price!)

Tips for stainless welding

need argon/co2 or pure argon gas

make sure the shroud is nice and clean

make sure the copper insert/tip is in good condition (replace if not 99p each)

get the earthing clamp as close to where you are welding as possible and make sure what you are attaching it to is clean(roughen with sandpaper)

are you doing it outside?if so do it on a calm day as the gas will be blown away and it will spit like mad!

move the torch when arched in either a circular or semi circular motion

practice on a piece of scrap (same material and thickness) play around with the wire feed speed and temperature control until you get a nice bead with penetration (comes through the other side without it sinking or making a hole

hope this helps fella!

[Steve-O 2007]

i am a self taught welder-have done loads now including making 2 exhaust systems from scratch-i got no qualifications in it jus practiced....ALOT!haha

Gasless welders are absolitely rubbish tbh,i have a cheap welder (cost £250) most of it is down to the wire feed, i roughened the wire feed wheel so it bites into th wire so it doesnt slip at all.(welds better than my friends one that cost twice the price!)

Tips for stainless welding

need argon/co2 or pure argon gas

make sure the shroud is nice and clean

make sure the copper insert/tip is in good condition (replace if not 99p each)

get the earthing clamp as close to where you are welding as possible and make sure what you are attaching it to is clean(roughen with sandpaper)

are you doing it outside?if so do it on a calm day as the gas will be blown away and it will spit like mad!

move the torch when arched in either a circular or semi circular motion

practice on a piece of scrap (same material and thickness) play around with the wire feed speed and temperature control until you get a nice bead with penetration (comes through the other side without it sinking or making a hole

hope this helps fella!

Plus stainless mig wire as well

Everything you ever want to know will be on this site - http://www.mig-welding.co.uk/forum/index.php