opening in the exhaust guide 114 such an opening is identified at 178 in fig3 this gives the operator a visual indication that the engine 103 is receiving coolant some water may separate from the exhaust gases in the idle exhaust gas discharge this separation occurs primarily in the expansion chamber 173 due to the expansion that takes place therein a drain passage 179 may be formed in the lower end of the chamber 173 so as to permit this separated water to drain in the embodiment of fig2 5 it has been noted that the exhaust pipe 144 does not extend substantially below the lower wall 147 of the oil pan 117 this however leaves the expansion volume 143 to serve two primary purposes one of these is to silence the idle exhaust gas discharge the other is to provide a cooling gap between the oil pan 117 and the exhaust pipe 114 although the volume of the expansion chamber 143 can be deemed additive to the volume of the expansion chamber 148 fig6 shows another embodiment which offers further expansion chamber capabilities this embodiment differs from the embodiment of fig2 5 only in the length of the exhaust pipe 114 and for that reason the components of this embodiment which are the same as those previously described have been identified by the same reference numerals this embodiment will be described further only in so far as is necessary to understand the construction and operation of this embodiment in this embodiment the lower end of the exhaust pipe 144 terminates substantially above the oil pan lower wall 147 in one specific example the exhaust pipe 144 may extend.