Got a Freight Shaker that we are getting exhast fumes in the cab? Getting bad now. Had the flex exhast all checked out and was told that it is the ERI Valve on the ehast brake that is leaking through and the fumes are coming in from that. This shop super told me they have had a few complaints about it from others drivers with the same motor. I asked how to fix it and he said all they can do is change the value out but it will leak thur again. Any Suggestions? Think I will red tag the truck xmas week as there are no spare trucks around and have it fixed, Anyone having this problem?