Separating an exhaust.

[Dave Plowman (News)]

I need to remove part of the exhaust on the old Rover to fit an oxygen sensor boss. One end of the part disconnects easily - its a flange coupling - but the other is the type where one pipe fits inside the other to allow some adjustment for length. Which is then clamped. It's a SS system and looks clean - so at least shouldn't be rusted up solid as steel ones do. The car is on axle stands so access is a bit restricted.

I was wondering about grinding an SDS chisel blunt and seeing if the hammer action works like an air chisel?

[Bob Minchin]

Get some graphite penetrating fluid in there the night before. Loosen the clamp, remove flange end and try to apply rotation to that end. Being SS I think it will move quite easily. I feel that hitting it in whatever controlled way is likely to distort it. Another way if that fails is to remove the clamp, run the engine to get it nice an hot and then aim a hose at the joint. The shock might just part it. Downside is that it will be hot and you wont be able to apply any hand force on it.

Good Luck

Bob

[Cicero]

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If you have reasonable access try the hammer tapping technique. Use a light hammer - e.g. a tack hammer. Tap *gently* all round the perimeter of the outer pipe, covering as much of the inserted section as possible. Try not to dent the pipe - just vibrate it. Keep some 'pull' on the pipe during the tapping if your arms are long enough.

Cic.

[Roger Mills]

I assume you want to part it non-destructively?

If it's stuck together, the best way of unsticking it is to rotate one part relative to the other by a few degress, rather than trying to drift it apart. You might be able to grip it to rotate it by using a strap wrench - intended for unscrewing oil filters.

[Dave Plowman (News)]

Snag is I've already removed the front of the system including manifolds for other reasons so running the engine isn't an option. I could try a hot air gun, though. I've given it a good soak in penetrating oil and will see how it goes. As you rightly said It would be better to avoid hammers of any sort.

[Dave Plowman (News)]

Very much so - it's SS and cost.

With the help of a neighbour and penetrating oil we got it to turn and pulled off - without tools. Couldn't have done it myself in a million years without damage. The part of the pipe now exposed was like brand new - still shiny.