might just be oil build up in the exhaust, put it on the water hose and let it run a little bit see what it does. Just don't rev it. Let it idle. take off the intake tube to the turbo and with the engine off, put your finger on the impeller gently and see if it turns freely. I've had then almost like seize up before, only turn it with your fingers, be careful their sharp. Don't use to much force to bend anything.