Hi everyone. I have a 2005 Cat 303CR open cab mini with around 4500 hours. Bought the machine a couple years ago with a cracked cylinder head. Had brand new head from Cat installed right after purchase. Machine runs and works great. However, it would occasionally overheat after a couple hours of work. This has gotten progressively worse, so now after about 20 minutes it boils over. Replaced thermostat with new Cat unit, with no difference. Left stat out, no change. Alternator/water pump belt is tight. I can let it sit and run for hours, and temp is fine. But 20 minutes of very light digging and water is boiling out of the overflow tank. Cooling fins in radiator appear clean (can easily see through them), and I've sprayed cleaner & hosed them out anyway a couple of times. No water in oil, and no coolant leaks. I'm suspecting perhaps a water pump with missing fins or a spinning impeller. (I can remove cap and fill with coolant, and when I start engine, level does not change at all). Is this something that seems to happen on these S3L2 engines? Any suggestions? I only use the machine for generally light work on my property and love how it works, but this overheating is getting old...
Thanks in advance!
Thanks in advance!