Pete.
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- 14,142
- Location
- Kent, UK
My daughter's VW car has been blowing at the manifold so it was time to get it apart and find out what the problem is before it goes for MOT and before she comes off furlough and has to go back to work.
Her nephew took the exhaust apart yesterday with some effort and phoned to say the stainless bellows has rotted so thin that they had parted around the joint, even though the rest of the exhaust was in good condition. A new down pipe is £180 & vat plus she needed the centre box changing which was just £35. I told him to bring it home and I'd have a look to see if I could weld it.
When I saw it I wasn't hopeful (you'll have to forgive the out-of-sequence photos, I didn't take any from the start because I honestly didn't think it was going anywhere but once I got underway I took progress photos to show here).
I knew I could never weld that back in place so I had a think and thought there might be a chance I could weld to the rounded top of the first bellow. So to get access I cut the pipe below one of the bellows and drilled the weld out of the ends with a tank cutter.
This released the end for good access. I cleaned it up with a wire wheel for welding. Didn't dare use a linishing pad on it.
I had some thin stainless sheet so I cut a couple of donut rings out of it and turned them to size on the lathe.
To get the gap up tight I pushed the right up squeezing the bellows and held it with a jubilee
After that I carefully tacked it in several spots , removed the jubilee, then very carefully and slowly went around the outside edge welding the ring to the bellow.
From here it was my intention to run a fillet weld around the inside to fix the ring to the inner tube. This turned out to be impossible (or at least beyond my skill level) because no matter how I tried the lip kept burning away. This was with a 1mm tungsten and about 40amps with the pedal fully down. It melted away before I even got to full power. Still, it came out ok.
Now it might not be obvious but this is a twin downpipe and to get access I had to cut off one bellow at the weld, so this one in the pics was welded on the bench, the other was welded in place (which was a lot more tricky, damn exhaust are difficult to position). Anyway, after welding both I then welded the loose one back onto the pipe.
Her nephew took the exhaust apart yesterday with some effort and phoned to say the stainless bellows has rotted so thin that they had parted around the joint, even though the rest of the exhaust was in good condition. A new down pipe is £180 & vat plus she needed the centre box changing which was just £35. I told him to bring it home and I'd have a look to see if I could weld it.
When I saw it I wasn't hopeful (you'll have to forgive the out-of-sequence photos, I didn't take any from the start because I honestly didn't think it was going anywhere but once I got underway I took progress photos to show here).
I knew I could never weld that back in place so I had a think and thought there might be a chance I could weld to the rounded top of the first bellow. So to get access I cut the pipe below one of the bellows and drilled the weld out of the ends with a tank cutter.
This released the end for good access. I cleaned it up with a wire wheel for welding. Didn't dare use a linishing pad on it.
I had some thin stainless sheet so I cut a couple of donut rings out of it and turned them to size on the lathe.
To get the gap up tight I pushed the right up squeezing the bellows and held it with a jubilee
After that I carefully tacked it in several spots , removed the jubilee, then very carefully and slowly went around the outside edge welding the ring to the bellow.
From here it was my intention to run a fillet weld around the inside to fix the ring to the inner tube. This turned out to be impossible (or at least beyond my skill level) because no matter how I tried the lip kept burning away. This was with a 1mm tungsten and about 40amps with the pedal fully down. It melted away before I even got to full power. Still, it came out ok.
Now it might not be obvious but this is a twin downpipe and to get access I had to cut off one bellow at the weld, so this one in the pics was welded on the bench, the other was welded in place (which was a lot more tricky, damn exhaust are difficult to position). Anyway, after welding both I then welded the loose one back onto the pipe.