I am making this 3" exhaust and when i put water in pipe it ALWAYS leakes, I add metal take metal away reweld doesnt matter, It leaks??? PLEASE HELP.

 

ttt

 

how big is the leak or leaks? where at around the weld is it leaking? what type of welding?

 

contamination makes pores, and that dp to exhaust flange weld is brown, which is usually a contaminated tungsten

 

mig welding galvanized exhaust pipe. .30 4cfm gas, they menetrate fine but it leaks and i dont know why. I cant tell where the leaks are coming from. The whole bead just saturates and in a few seconds...drip......drip, but they ALL leak, im baffled

 

So how do i fix the problem? I have been grinding around the edges first to make sure its clean?

 

If that 4 CFM wasn't a typo, then crank it up to 15-20, especially if you're outside.

 

No im inside only have a small fan pulling air. doesnt make much breeze. My video i got with the welder long time ago said between 2-4, now it didnt specify any changes due to material? So is 10-15 something you use per material or should "this" welder be used at 2-4? Sorry ive had my mig for about 6 months now, i just now got gas for it when i started this project

Clark mig welder (does not excpet flux wire)

 

crank your gas up man. work your way down from there. galvanized usually isn't very fun anyway.

 

You are likely welding too cold, and/or having poor stops and restarts that are leaking. Weld hotter and roll the pipe such that you're welding downhill.

 

So should I grind off whats there or just make wider beads on sides?Im off to bed but ima get some pics tomorrow so everyone can see what im possibly doing wrong. Thx for all of everyones help to this point.

 

Whichever will make it look the way you want and take the time you want to spend. Grinding it off will be faster, but welding it more will be faster and look worse. You may want to practice a bit more before starting up on it again.

MIG is bad about having cold starts some times. Th help fight this on restarts, fire up about 3/8" ahead of where you stopped, then quickly back up and consume the ENTIRE crater that you left when you stopped, and resume forward.

 

I think you will find that exhaust soot will seal up those little pores in no time.

 

would it be possible to post a closeup of the weld itself?

are you downhand welding or trying to uphand it?

 

its the galvanized coating, more specifically the zinc in it. Zinc does a number on welds, you'll end up with cracks every time, no matter what filler you use. Try laying a pass over top of what you've got now, see if it'll seal. By laying a pass on top, you'll reduce the amount of zinc in your weld, but without totally removing it, its always gonna be there.

 

Would preheating help?

 

nope, you have to get rid of the zinc

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Canuk_SiR &raquo;</TD></TR><TR><TD CLASS="quote">its the galvanized coating, more specifically the zinc in it. Zinc does a number on welds, you'll end up with cracks every time, no matter what filler you use. Try laying a pass over top of what you've got now, see if it'll seal. By laying a pass on top, you'll reduce the amount of zinc in your weld, but without totally removing it, its always gonna be there.</TD></TR></TABLE>

Although the plating is not fun to weld and I agree with your point, it can be done. Exhaust shops weld this stuff all the time, and they don't remove the plating.

There's too many things that can go wrong to blame leaks on this plating. Not meaning to sound rude, but the welds are pretty lumpy. I'd have to say that welder error is a more likely fault than the coating on the metal.

 

First off you need to set your regulator to 20 cfh if there is a breeze then you need to either block it or set the reg even higher. The next thing you need to do is learn how to weld before you try to weld up good parts. Get some scrap and practice what your trying to do on the car. I see allot of welds on top of welds in the picture and they look cold. Need a better pic! what type of machine do you have? Some of the 110 welders don't care much for 030 wire. If your welding with a marginal machine the best thing is to grind any coatings off so the wire can heat the steel directly and not waste power burning off the coating. Practice and if you can't get it then ask someone that knows how to help you. Once you weld with a machine that is set right you"ll know what to look and listen for. A machine that is set right will have a sound while welding that you will learn to recognize. This is assuming that you know the proper distance and angle to hold the gun. Also make sure that the nozzle is clean because welding coated metal tends to load up the nozzle with spatter. Get some better pic's because it's hard to help when you can't see the probelm real well.

 

by all means no offence taken, ive been welding for um 5 months self taught and without gas, i just got gas 2 days prior to this thread, so i know im no master welder as stated in other threads thats why im here to get you guys opinions and teachings. Ok im going to grind off whats there and take a pic then maybe you guys can help me fix my mistakes. I made a full 3" exhaust to the back so i have about 8-10 rings which leak so id like to learn this before it goes on the car, Thanks again for everyones wisdom and patience.

 

in just to throw this question out there, how do you guys do rings? can you roll it in one bead?

 

You are a badass if you can do a pipe without stopping/restarting at least a couple of times. I normally stop, restart 3 times when doing a 3" pipe.

People out there can do it, but it takes ALOT of practice to be able to do it and have it turn out better than stopping and restarting would have.

 

i just thought of something else, are you buttwelding or are you flaring the pipes and sliding them together?

 

sorry did get to the exhaust tonight, i moved onto another project for now, but i am butt welding them. I would know how to slide them together?

 

they would have to be flared out, sometimes you can get bits that come flared, i have a hydraulic bender (exhaust tubing bender, pre-mandrel) that i use to flare the pipes so they slide into each other.

it's generally quite difficult to buttweld exhaust pipe, i would still like to see the closeups of the welds to make any sort of judgement call or recommendation though as to how you can fix the problems you're having.