JD 320 leaving burn mark in lawn when stopped

[jyatson]

Any solution to a JD 320 leaving heat burn marks on lawn when left running in place even for less than a minute?

 

[bertsmobile1]

Repair/replace muffler if it really is a heat burn.
Adjust the front deck height if it is a helicopter burn ( swirl )

 

[redmondjp]

Check muffler exhaust pipe. If it discharges down, this will happen. It should point either towards the front or the side (or in-between).