I just bought a 2155 with 2500 hours.First time I go todo work with it the temp gauge constantly rises from the bottom of the dial to red over a 10 min ride to get an implement. I filled the rad reservoir to the top with distilled H2O looking for bubbles to check for head gasket/crack, no bubbles. With the tractor idleing and the temp gauge on the edge of the red zone I removed the rad cap and put my finger in the coolant, not hot, slightly above my body temp. After shutting down the tractor the coolant temp in the reservoir did rise to slightly uncomfortable via finger test. There is a hole that has been patched with a screw/thread tape in the reservoir, could this be a cause(I know probably not but possibly an indicator of something)? To my limited knowledge base I think water pump or thermostat. Am I on the right track? Also is there an online source for water pump removal instructions or what manuals do I need to order?