A long story with a question or two. I was mowing with a 60" deck on my JD 445 and noticed the engine temp gauge was very near the red. Quickly went to the shed, let it cool off a couple of hours. The radiator overflow reservoir had what appeared to be sufficient water in it but I filled it all the way to the top anyway. Started mowing again. It got hot again; after just a short time. Let it cool over night. looked in the radiator; could see the coils with no water over them; even though the reservoir was still full. Filled the radiator and mowed again. Seemed to be okay but as I closely watched the temp gauge, it was fairly constant at about 30% of the way from cool to hot. But occasionally the temp would quickly climb to about 50% for just a few seconds; then drop back to the 30% level. Is this normal? Is there something possibly wrong? The air temp on that second day of mowing was very cool, about 60 and I only mowed for 30 min. max. Thanks.