With the radiator cold, just use a garden hose. When water comes cleanly out the other side, your radiator is clean. Work your way up and down, from one side to the other.I’ve noticed my l3800 has been running a little hotter than normal. Not danger zone hot, just hotter than usual the last few times I’ve used it to cut the grass. I bought an extension for my air compressor so I could reach in around the radiator a little better. I didn’t really notice too much difference.
Can I use the coil cleaner that comes in a spray can? The kind you would use to clean your home AC coils.