I was working the D46U yesterday afternoon winching trees out of a fence and piling them. the engine coolant temp was pretty much a constant 180 F .  was working it pretty hard but the tractor idled while i got off and hooked the cable to each tree and then drug the tree about 500 feet to the pile. then idle while i got off and disconnect the cable and start over.  i probably need to blow the dirt out of the radiator?  is this above normal for a D46U?  outside temp was pretty close to 90 F.

Thats about right, suction or blower fan? blower fan will run a little hotter. Good to clean out the fins every now and then.

Thanks. seems i can remember reading somewhere that the operating temp was around 160F. the fan is a sucker. i just checked the nebraska test of a 1949 D47U and the 100 percent belt load for 2 hours was 174 degree F and the varying load two hours was 180 degree F. so it must not be to bad plus my SW gauge could be off by a couple of degrees and as a side note the ambient temp in the nebraska test was 82 degrees for the 174 reading and 90 degrees for the 180 reading.

any idea what the red line on the oem gauge would be in degrees?

digitalcommons.unl.edu/cgi/viewcontent.c...ext=tractormuseumlit
here is the data

I believe the red is starting at 210 degrees. Beyond that is head cracker temp.

Thanks Rome. that is good information.