I was working my 2011 Farmall 65A (598 hours currently) with my NH RB450 utility baler and noticed my temperature gauge was climbing. Now it was 98-100 degrees outside at the time and I was baling on some hilly terrain running right under the 540 pto mark. I cooled the tractor and added almost 2 gallons of coolant. Continued on and the temp never rose again. Pulled back in the yard and let it cool down. Checked and saw I lost coolant again. No visible leaks, no raised oil level or milky residue, and I never see any exhaust smoke (white or black). I know that odds at this point was either radiator cap or blown head gasket.

Now here's the kicker, I thought the radiator cap said 60 as in kpa. Looked in my manual and saw the spec was for 90 kpa (13.1 psi) radiator cap. So naturally I got a 13 psi cap and premixed 50/50 and filled it up to the appropriate level. Left the cap off, fired the tractor up and looked in the radiator and saw no bubbles. Put the new cap on and went and loaded bales in the barn. When I finished, let it cool, removed cap, level appears to be the same. Fingers crossed that there's not a head gasket leak, won't know for sure until I borrow my buddy's gauges and work the tractor for a longer period.

So here is the BIG QUESTION: What does your radiator cap say for pressure rating? My "60 kpa" turns out it was 6.0 psi. This pertains to the 65A and 75A per the specs stating 13.1 psi. If you've had a similar problem I want to hear from you.