I have a 2000 ch613 with a 1996 remaned engine that was swapped in. It had to be retrofitted with a tubular style oil cooler because the pancake style one was slightly different in shape at the mounting area to block. Some of the plumbing had to be changed as well. The tractor appeared to be overpreasurizing and was blowing out of the over fill. I took everything apart nothing clogged ,changed water pump no cavitation on housing,changed thermostat, air compressor,did combustion test as well negative . Still does it but not all the time loaded or empty. Temp gauge will go up high cold air will