turbo crack

[jonnyshaw49]

hi just wondered if anyone could tell me why the inside of the turbo exhaust housing always crack? i have three spare turbos 2 t2/t25 and one t2 none of them have play in the turbo shaft but all have air line cracks in the rear near the actuator valve bit, what does this mean? will the turbo not function properly or will they be one there way out? can anyone shed any light on this wouldnt mind selling one or two but dont want to sell dodgy turbos thanks

[mlb123]

common thing to happen if its a crack around the penny valve area, shouldn't cause a problem unless splits gone right through the housing to the outside, only seen this happen once though on a kkk turbo....

[jonnyshaw49]

what causes the crack? is it just heat, what happens when the crack goes right through? thanks

[mlb123]

what causes the crack? is it just heat, what happens when the crack goes right through? thanks

http://www.iwsti.com/forums/2-5-liter-litre-factory-motor/116919-vf39-wastegate-crack-2.html

check out this link, the crack in lower pictures would be one to worry about, although it would probably run ok, yeah i guess its just heat damage, things expanding and cooling. especially in the exhaust side of things, with the kkk turbo i saw the crack had gone through to the back of the manifold housing because there a one piece type setup, and that was leaking to the outside, managed to get that welded up and it was fine, infact its still going fine now :)