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Old 18th February 2009, 13:02   #16
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Originally Posted by anjan_c2007
And as regards welded silencers one can go ahead with it if the runs are shorter and restricted to the city at low speeds. The moment the silencer heats up during long drives, all the welding will of any kind whatsoever will fail.
Hmm. Are you suggesting that heat will undo welding ? Have to disagree with that.

I have had the following stuff done on the exhaust system of our M800 :

1) Minor leaks in muffler welded.
2) Muffler and pipe joint welded.
3) Replaced the full shell of the muffler with a new one that was welded on.

And post these welds, we have used car for short/long drives and they have lasted without any failures.

P.S.: I guess I am right by calling the part just before exhaust tip as the muffler.
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Old 18th February 2009, 13:14   #17
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Originally Posted by anjan_c2007 View Post
And as regards welded silencers one can go ahead with it if the runs are shorter and restricted to the city at low speeds. The moment the silencer heats up during long drives, all the welding will of any kind whatsoever will fail.
Dude you need to learn a lot about welding. Seriously I can't keep myself from laughing.
On a more serious note, if this was the case then we would not have welded exhausts systems at all.

Last edited by vikram_d : 18th February 2009 at 13:16.
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Old 18th February 2009, 13:18   #18
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Originally Posted by Ravveendrra View Post
Often there is back pressure in the exhaust system, when this happens if the oil in the muffler gets sucked into the catalytic converter or carbon collecter, will it harm these components?
The exhaust is a 1 way system, nothing will get sucked in backward. The catalytic converter operates at ~900*C anyway - so the oil has no chance of making it back to the Cat without evaporating.

There is no way in hell I'm pouring oil into my exhaust though. An exhaust system should be made out of stainless steel and last a lifetime. Anything else is just a compromise!
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Old 18th February 2009, 15:18   #19
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Originally Posted by vikram_d View Post
Dude you need to learn a lot about welding. Seriously I can't keep myself from laughing.
On a more serious note, if this was the case then we would not have welded exhausts systems at all.
... and to think, I had this misconception that proper welding usually produces a joint which is stronger than the surrounding material (for mild steel welds)
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Old 18th February 2009, 15:30   #20
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... and to think, I had this misconception that proper welding usually produces a joint which is stronger than the surrounding material (for mild steel welds)
Actually all welds are stronger than the surrounding material, not only MS ones.
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Old 19th February 2009, 14:43   #21
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In any case, as I mentioned earlier, normal running of engine ensures that your exhaust circuit interiors are always coated with an unburnt/partially burnt oil slick.
Don't believe me? Open up ANY car exhaust.
I had to replace the muffler of my Palio recently, and these are my findings -
1. The whole exhaust assembly is made up of four different sections - from the exhaust from the engine, to the cat, the exhaust pipe and the final muffler assembly.
2. The hole in my muffler showed rusting from outside - just touching it with my hands caused the rusted portion of the muffler to break and fall in pieces.
3. *** guys said replacement was the only option - quoted 5000 for the part and labour additional.
4. Took it to a garage near my house, to explore the possibilities of welding.
5. The guy was helpful - raised the car on the hydraulic platform and pointed out how the entire assembly works.
6. The muffler had a couple of holes - small ones (which by the way was making my car sound throatier!); but when tapped lightly, it started crumbling.
7. He said, I can cover these spots by welding - BUT, the rusted area will continue to expand and eventually the entire unit will fall down.
8. So, decided to replace the unit (he had one for Palio and agreed for 4000 with labour)
9. Dismantling the existing one itself took time - the tube on one side was welded, and had to to cut off with a gas welder.
10. New unit was fitted with a collar (he advised against welding and guaranteed that the collar won't work out loose)
11. Noticed that there are rubber grommets which actually hold the silencer in place and one was torn - these parts seem to be crucial in holding the entire in assembly in place.
12. Tried to see what the old muffler was like by hammering it (in fact, wanted to haggle with them for scrap value... he, he..) - but when one part was opened, it revealed a small maze inside and the entire innards were also rusted.
13. I was told that the water inside (as has been commented) is the main culprit for rusting. He said water gets inside even washing the car (as it is pressure washed).
14. Don't know how pouring oil inside will help - because we can't ensure that it will get evenly coated; and the hotter the muffler gets, the more the oil inside is going to burn and leave sludge inside, which will then trap moisture and lead to quicker rusting.....
15. Personally think that after spending at least 3 lakhs (5 lakhs in my case) on the car, spending 5000 once in three-four years should not be an issue.......
16. Finally, don't have to bother when the entire unit is going to fall off or the welding will give away....
17. There is a difference in performance.... the pick up with the muffler with hole seemed slightly sluggish.... after the new one, FE seems to have marginally gone up......
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