Hi all, new member here! Been doing lots of reading on the site and finally joined. Bought myself an excavator and have been going through it. machine is a komatsu pc200-5 Sn: 50040 6,900hours. Engine: s6d95L-1 Been having an engine heating issue when hydraulics are being run. Following advice here, I super cleaned radiator then moved on to thermostat and water pump when that didn't solve it. Found this at the water pump discharge on the head upon removal of the pump. Is it just an enlarged passage or is that not supposed to be there at all? Ignore it? New head? Thoughts? Thanks!
It's a coolant plug, without the plug, your coolant is bypassing and not circulating right causing higher temp.
He's referring to the rotted metal and subsequent casting hole, i think.
I am referring to the rotted hole. I am not familiar with these engines and was uncertain if there was supposed to be a coolant passage there which was just eaten larger or if that rotted part was supposed to be completely blocked off. That entire port is where the water pump discharges into the block.