I know from my machining days,you can work harden metal to a point you need ceramic inserts to turn the metal.
Is it the same for welding? I have welded and welded for 6 years on my muffler,and I'm about to wrap the leak with fiberglass then resin,and put aluminum tape on top.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

If you are electric welding then the chance you get rapid cooling and a brittle weld is possible. Gas welding won't do this (so quickly) as the heat effected zone is more often than not much larger...


...but you are not necessarily hardening or fatiguing the metal by welding alone (unless you're in the habit of quenching the work piece for some unknown reason). If you were welding say cast iron you'd wrap the weld in blankets to slow the cooling - but for steel this isn't necessary.



On an exhaust - dirty - you are more likely to have gotten muck in your welds - this is more likely to be the cause of unwanted cracks and your repeated welding activity.


At some point or other - I'm sorry to burst the bubble (!) - but you just have to go and buy a new exhaust...

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Or cut off,the affected pipe,and reweld? I have a sears 110 welder,wire.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

welder

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

Depending on the nature of the leak another alternative to polyester resin and glass mat or cloth that I've used is a construction adhesive of the Liquid Nails type.

It sets up not as brittle as resin and it has a tenacious grip. On the down side it takes a good day to completely set up. But on the up side, it's $5 for a giant sized tube, there is no mixing, it's the consistency of peanut butter so it pretty much stays in place while it sets. Best practice is to give the area surrounding the leak opening a good wire brushing and even a wash with soapy water to get rid of any surface contamination like dust, dirt, grease or oil that could compromise the adhesive's direct adhesion to the muffler material to optimize the longer term success of the fix. If there is a larger gap the stuff can bridge and fill those easier, if an opening is too large you can apply a thinner coat and then insert a reinforcing patch of the fiberglass drywall seam tape of even window screen or hardware cloth. An hour or two later you can butter on a second nice thick sealing layer with something to adhere to. This stuff works perfect around the seams of the can. I've used it to patch mufflers but the closer you get to the engine heat source with it I can foresee it not being as suitable and having a higher chance of failure.

Sometimes you've got to make things work until a better fix can happen.

going to Lowe's to get liquid nails, thanks

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

It looks like your welder is a gass-less MIG in your picture


So I guess you are using flux coated wire - this isn't that far removed from stick welding. I imagine it is quite a difficult thing to use on thin low quality exhaust metal. I've welded similar things before with MMA / stick and I find whilst I can "get it to stick" (as in stay on there) it isn't the best solution for a long term fix. This is the kind of thing that might be necessary to get you through a safety inspection but realistically it is much closer to a temporary fix.


The problem you will find is that keeping the area clean before and during welding is a challenge - you can just blat more and more metal on top but even then it is quite likely it will just crack and fall off.


You would probably have an easier time with gas shielded welding - especially after you've been learning and struggling with the system you've got - but the price hike in equipment and consumables is considerable.


Personally I'd just take the sodding thing to an exhaust shop and get them to replace the rusted / broken bit as I hate working on exhausts! At the best of times (used) exhausts are nasty vindictive bastards - they cut and leave nasty soot in wounds that itches and itches and itches...


...I've replaced entire systems before just to avoid the pain!

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

My problem no money,at least $35. to put in the air.Moving in May,going to sell home to help son,buy him one.He will care for the miss'es if I should kick off.Don't feel I'll be around much longer with health problems.
Yeah everything so expensive now

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

If you're in a time rich cash poor situation striking up a friendship with the local scrap yard might be worthwhile if they happen to have lots of old Mercedes with half OK parts on them.

If not - removing the exhaust to see what needs to be done is arguably more work but it does give you a better chance to weld and / or smear on whatever fix you desire to try and get the fix to last a bit longer.

New exhaust sections are sold here in Europe at fairly low prices - not sure about your neck of the woods though...

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Mind your health Nate ~ your Son still needs you no matter how independent he seems .

If the Liquid Nails works, please post a picture as the last time I checked there were SIX different Liquid Nails and I had no idea which one to choose.....

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

lowes has a silcone fireplace putty,that good to 600 f. not that hot back there.Bought it,and aluminum duct tape,with paper backing,its thick.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

worked good,takes 24 hours to harden. Nice ride today

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

Exhaust temperature is only moderate on a diesel I think. So this probably was a reasonable approach. It reminded me that I have not had a rusted out exhaust component occur on a car for a lot of years.

Part of a badly bent up one of the wives car got replaced. In the last few weeks though.

You can semi determine the condition of an exhaust system here by the amount of rust on the exterior of the parts. It was noticeable in the south. That the outside of the pipes remained rust free pretty much. So there would be no way to estimate their real used condition. Or probably remaining service life. Since they rust out from the inside only I surmised.

I just really just posted to mention. I know there is a dedicated muffler cement on the market and has been for a very long time. How good it is I have no ideal. Welding is usually a lost cause as the area of metal near the weld tends to oxidize very fast.

A small future project I have. Is to weld up a box etc. To act as a muffler for the emergency power generator. With a removable lid so I can change the glass fibers out. That generator is somewhat loud. Glass pack type mufflers work better than baffle configurations for those I understand.

Please share what & how you do this ! .

I got a steal of a deal on a brandy new Chinese (of course) two cylinder 7 KW (IIRC) generator, it looks like a close copy of a Honda one but the noise level is incredible and I'd like to know how to reduce it .

TIA,

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Easiest way is too take pieces of waterproof plywood and baffle the generator. Just basically leaning them against the generator. At an angle. Leaving sizable gaps for the cooling air to flow through.


It seems to deflect a lot of noise downward. Works best with the generator on dirt as it seems to absorb a lot of the reflected noise. Car type mufflers help but not as much as one would expect.


On your size generator I would try leaning some form of scrap material against it first as a test.


You are absolutely right as most if not all the Chinese generators are very noisy. Mine is as well. I think they just make a lot of noise that is not really exhaust noise, That is why the baffle system of the whole unit works. Does it drop the noise level enough depends on the individual. It does drop it though.


A glass pack type muffler works better than a baffle type. It is not a high priority for me to build the muffler as we seldom lose power. The generator was a gift from the son in law. It has no hours on it but he could not find the old gas residue issue in the carb from storage. . So he purchased a new one and gave me this one. Tests with add on mufflers are just not so great. Or give less noise reduction than one would or should expect.