420C overheating problem!!!!

[jdman123]

I have a 1956 420C 5 roller which might be overheating, but I would like some advice. I have put a new temp guage on it last year. The machine is running at 210 F when I work it over an hour. i have noticed that the oil pressure drops from 22psi to 10 or less when it is running that temp. I usually shut it down to cool off. What should I check? The belt does squeak some but it is turning the pulleys fine, I think. The coolant is new and the machine runs fine. Would the higher temp cause the oil pressure to drop or do i need a new oil pump. If so does anyone have one for $$$$
I did check and i think the thermostat is 160 degress on this machine. any help would be great!!!
Thanks,
Shawn

[JD440ICD2006]

420's use a 160 degree cartridge type thermostat.
I will list a few things to check.
You must have the correct type of radiator cap that will maintain around 4 PSI.
Things that can make then run hotter:
The timing could be off,
The carb could be set too lean,
The water pump could be failing,
The belt could be slipping more than you realize,
Could be the wrong type or failed thermostat.

As for oil pressure dropping, a drop is normal as the engine gets to higher temps, but it could be wrong type of oil, could be a failing oil pump, could be crankshaft bearings worn too much.
I hope this helps.

[jdman123]

Thanks I did some checking and it looks like the water pump belt was turning, but it was slipping. I could turn it with my hand. The radiator also had alot of dirt in it. I have washed ot out. The problem I am having is that the set screw on the pulley is broken off flush. I have not found a drill that can drill this set screw it must be a grade 8. What are good tips to get this thing drilled out so I can tighten the puley?

[Ray III]

It is usually easier to weld a nut to a broken bolt than to try to drill it out. That may not work since the bolt is bottomed out and therefore tight even with the head missing, but it would at least soften the material for drilling if needed.