Air leak turbo related??

[farmboy]

Any ideas please. My 09 prostar Cummins has developed a very noticeable air sound whenever It reaches 15lb or more of boost and when using the jake. It also sounds like a short burst of air each time the auto trans upshifts. Seems to come from the rear part of the motor but wont do it at all by just reeving the motor while sitting still.I went to a dealer and they put new CAC (I did see the leak) and all new hoses and clamps for the turbo lines. $2800 later I left there and the problem was no better at all! It would make boost in the high 30's before and now 30 is the top and the jake doesnt seem to hold as much. I would be greatful for any help

[marek4792]

Check your vband clamps because sometimes with new orings if the two surfaces are not 100 percent it will leak like you described

[Nilao]

Check the egr crossover flex tube on the rear of the motor. If it ruptures it will cause a loss of boost as well as engine brake power due to loss of back pressure.

[Rawze]

The pipe that comes off the EGR valve, going to the venturi likes to rust through and leak like mad.