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coolant filters

  1. Coolant hissing noise

    Engine 911
    I got a Sinister bypass coolant filter about a month ago in my 2006 F-250 6.0 and now I am getting a hissing noise from the back of the engine, right where the outflow for the bypass is spliced back in. There have been no leaks and I even have a new filter on there - and still the noise...