Whats Hot?

Me thinks you should take a garden hose and air hose to the fins of the radiator and clean the gunk/dirt/crud out from between the fins to be sure you have air flow. Then if that doesn't help, drain the coolant level down so that you can see if the radiators tubes are plugged up. If they are, you can try aftermarket flush to clean the system or you can "rod" the tubes.
After all why blame the Thermostats???
Their job is only to open and close.

Is the coolant blowing out of the rad? Get it warm again and as soon as it gets up around the red stop and feel the top and bottom rad hoses
That should give you a good idea about the thermostats, rad core and head gasket.
Later Bob

You can check the thermostats in place if you want. They can be a job to pull them to check if you don't have the right puller. I have removed the top of the thermostat housing and hose to radiator, allowing the water to drain down some in the radiator top tank, but the thermostats should hold it from draining on down if they're closed. Remove the section of hose and replace the cast iron top on the housing. Then take a torch and heat the cast iron housind below the thermostats to heat the water inside. You can see if they open up and allow water to rise up in the housing or not. Once you get it hot, and water is level and steaming, drain the radiator down with the drain cock in the lower pipe and quickly remove the top of the thermostat housing to see whether the thermostats are open.

Also check fan belt tension. It doesn't have to be very tight, only snug. Operator's instructions has a spec of 9/16 to 13/16" slack at mid span with an easy push.

You cannot tell much about the state of the tubes inside the radiator because there is a cast iron plate in the way below the filler neck. It's not too hard to take off the top tank and rod the tubes out yourself. Link to the thread I recently started
http://www.acmoc.org/bb/showthread.php?17111-D6-9U-running-HOT-and-radiator-cleaning&highlight=D6+radiator

I used an old dipstick from a 621B scraper transmission to rod my radiator on my 955. It fit perfectly in the tubes and is very stiff so it doesn't tend to bend when you hit the hard stuff.

Good evening Tim,

I am thinking back 40 yrs or so to the 318 engine in our D6 9u. It seldom had anything added to the radiator but creek or pond water and antifreeze. Lots of sediment and scale forming resulted.

There was a plug in the right side of the block. When it over heated, we would remove the radiator cap, pull the plug, and begin flushing the rusty coolant by adding water to the radiator. Lots of rusty scale and mud would gush out. You may try this before going into the radiator tank to rod out the tubes. I would also check the thermostats before pulling the radiator tank. The 17A acted similar to what you described. I figured the thermostats were fine and pulled the radiator and removed the tanks. The tubes looked new, not a bit of plugging at all. I found one thermostat had come apart and no way would it ever open. The other thermostat was stuck partially open.

NAPA had thermostats for about 30 dollars each. Replacing them fixed the problem. I run a 50-50 mix of distilled water and green antifreeze and add a bottle or two of Wix-cool per label directions and have had real good results.

Best regards,
Thomas

Thanks for the replys!
I cleaned the outside of the radiator ,plenty of wind blowing through.
Still getting hot , from 170 to 205 and climbing in about 5 minutes . I can rev the engine and it will push water out of the radiator so Im assuming that would mean the regulators are open. Not much heat exchanging going on with the water inthe neck and top tank hot enough to scauld you, the tubes and air-flow are ice cold.
Like CCJersey said , you cant see inside the radiator because the view is blocked.
My question is how did they expect you to service the radiator on a d-6 tractor with a hard-nose ?
Looks like the hardnose has to come off to service the radiator ?
Any insight on removal? thanks Tim

I'm assuming you have a hydraulic dozer, 'cause the cable dozer hard nose doesn't get in the way at all, you do have to remove the front radiator guard to get to the front row of bolts holding the top tank on.

Be careful if you do pivot the hard nose forward and out of the way of the radiator. That sounds like a good way to get pinched if not "sheared" if that thing tips unexpectedly. All same, it does sound easier than complete removal. Don't forget the driveshaft for the hydraulic pump when you get ready to pivot it.