I've attempted a 'hopeful' improvement for the 3.8L Plenum EGR passage. Please view the attached image. These ceramic sleeves are available on Amazon.
Link
Its a loose fit in the bore but it works out to where the can't leave the bore (the injection molding stops it on the top side and the silicon gasket stops it on the bottom side.. I glued/sealed the sleeve in the bore with high temperature Red Gasket Maker rated for 600 deg F.
Link . I have several of these to do, please let me know if anyone can think of a glue or sealer that might work better. I'm 'thinking' the ceramic will be effective at reducing the temperature that reaches the plastic plenum.
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