it has 300958 kms and its from around the cylinders, i have checked the sparks, it sorta sound like its combusting very loud.

How many miles on this??? I have worked on these cars before. Their biggest vulnerability is to the use of American "green" coolant. It eats the aluminum in the heads like Swiss cheese. It takes some time for this to happen, though. The knock you are hearing should be examined by someone who knows engines well, as this might be as serious as a rod knock, or as simple as a sticking lifter. These were not Toyota's finest engines, although they are plenty good. Hopefully, you have been using genuine Toyota coolant and synthetic oil. If not, you may be looking at some major expenses. Good Luck!!