This study deals with experimental and numerical investigations of the time response of a mantle thermocouple. Using two different experiments, a clear influence of a glue covering is indicated. The numerical analyses are done using a stand-alone structure and a coupled flow-thermal calculation. Both computational results agree with the experimental data and established a detailed flow investigation of the VxG-experiment. The experimental and numerical investigatons confirm that a thin glue layer of about 1
is responsible for a time delay of few seconds.