D6b running a little too warm.

I have a d6b sn 44a11367.
I have had it since last September.
It has started to run a little warmer since ive been working it a little harder.
Today I ran it for about 30 min. The temp guage showed about 190. While I was pushing dirt it would up over 200. If I stop and give it a break it goes back down to 190 but heats right back up when I start pushing.

Now I know these engines like to crack heads but hopefully thats not the issue here.
There is no water in the oil and I don't see any bubbles in the radiator with the cap off.

But what I did notice today is the top radiator hose was very hot. The bottom radiator hose was barely warm.

So that leads me to ask the question. Is the radiator core plugged? Or is the water pump not pumping?
Also I did replace the thermostat when I got it last year

Thanks in advance

Clyde

Check these things out....
Sounds like plugged core to me.
Also check v-belts and pulleys for wear and slippage

I think a plugged core too. At least I hope thats all. I also replaced the belts a little while ago and I dont think they are slipping.

The top tank unbolts from the core right?
Is that the best way to clean the core?

Thanks

Yes, the top tank unbolts and that's one of the ways of getting access. I use an old band saw blade with the teeth ground off to rod the tubes.

Just wanted to say thanks for the help. I used an old bandsaw blade and ground off the teeth. "Rodded" The radiator out. Put it back together and it sits on 190 once its warmed up and does not move!! Now we will see what I can break next.