ajh Posted December 7, 2009 Share Posted December 7, 2009 Had a V8 downpipe crack cleanly through about 2 inches below the header flange. Would this be something that could be welded back together? It does not look badly corroded at first glance but given that the D2 is my sole transport with the starter in the Mini bad (yeah, I know I should have fixes this) and the 110 in parts and snow on the ground keeps the Fireblade out of the picture, so coming up with a quick fix would be nice as it is currently kinda loud. Quote Link to comment Share on other sites More sharing options...
andyb Posted December 7, 2009 Share Posted December 7, 2009 Yes I would say so, with no problems. Obviously easier off the truck and welded up on a bench. IME, cracks are often jagged enough that you can use them to realign the two parts. Also a 'band' hammer formed around a piece of pipe of similar diameter can help as an external joiner if you think that the metal at the crack is too corroded to weld. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted December 7, 2009 Share Posted December 7, 2009 i'd try to lay a few tacks on the two parts with them in situ before removing and welding fully on the bench. Quote Link to comment Share on other sites More sharing options...
ajh Posted December 7, 2009 Author Share Posted December 7, 2009 OK thanks, I broke my heel a bit in Peru a couple weeks ago so I guess I need to get a shop to do it but at least it is a viable option, thanks. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted December 7, 2009 Share Posted December 7, 2009 I'm not sure what the technical term is or what exactly happens but the metal changes characteristics on an exhaust after it has been repeatedly heated and allowed to cool, as such welding up and old bit of an exhaust can be a real PITA and many give up on it as can just seem impossible, so the trick will be to find a more than decent welder, and not just some garage that has welding equipement Nige Quote Link to comment Share on other sites More sharing options...
andyb Posted December 8, 2009 Share Posted December 8, 2009 find a more than decent welder, and not just some garage that has welding equipement I must be a better welder than I thought then as I really not had any problems......other than some of the pipe on cars is pretty thin Quote Link to comment Share on other sites More sharing options...
mobyone Posted December 8, 2009 Share Posted December 8, 2009 it shoould weld no probs. the only prob that may arise are heat cracking the crack further or contamination by oil/fuel. drill a hole either end of the crack to stop it progressing further. it should be fine though as it is not cast. the heating and cooling does change the metal properties a bit, normally would be more worried for oil/fuel contamination of the downpipe, but just get whoever is welding it to heat it with oxy acetalene to make it weld properly and burn the carp away and then weld whilst still hot then leave it to air cool (normalise). obviously prep it with an angle grinder if you can, but not absolutely necessary. no need to remove it if all this can be done in situ. the only reason you would need to remove it is if you cant get at it for the prep/heating/welding. though welding under things is never without pain! not sure how much time it would take if it needed taking off and doing then reconnecting. but it may well be worth costing it against a new or good second hand one also. then you can get that one welded up and punt it on to offset the cost if you replaced it. richard Quote Link to comment Share on other sites More sharing options...
ajh Posted December 8, 2009 Author Share Posted December 8, 2009 The 'crack' is a complete one about 3" down from the header connection so right now the header is venting into the engine compartment. Off to see if I can get someone to fix it. Quote Link to comment Share on other sites More sharing options...
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