petrol mower very loud and overheating?

Very difficult to give you any sort of answer until you inform us of what mower and what engine you are referring to- in fact it would be impossible.

Is it an air cooled engine or water cooled? If it's air cooler, what makes you say it is overheating? What are the symptoms?

pleasant
September 2011

Depends on engine.It could be the ignition timing has slipped into retard.

davidj
September 2011

probably a head gasket you can buy one easy enough but
if you are not very good with engines it would probably need to be sent in it is the bolts on top by the spark plug undo them remove top remove old gasket make sure there is not bits still on there and put new gasket on tighten bolts diaganal and give it a pull that should solve your problem

matti
September 2011