Scratching head help detroit 60S 12.7

I don’t have a manual fan switch.

 

You can put a pressure gauge on the pressure side of the pump. I've never seen a 60 series pump fail and cause an overheating issue, and I've worked on quite a few. If it wasn't pumping, you wouldn't make it two or three miles on flat ground without overheating

 

The fan is running non stop because it can't vent the air after the solenoid opens and closes. It's keeping the fan side hose charged.

Also, it wouldn't affect an air leak on your A/C control

 

I like the 185's for summer, but 195 the rest of the year. I stay with 195's, but stay more north. If I was staying south, i'd definitely run 185's.

 

When I put that metal plug in the leak stopped.

 

If its going to run hot thermostats wont control it, thermostats only control how cold it runs, once they are open at whatever temp they stay open. Yours could be faulty though, stuck half way. The parts lady at a local truck dealer said she sold a lot of thermostats when I bought a couple years ago, they dont last forever. I have had my detroit 60 for 5 years and have replaced them twice now. You can find good ones on ebay stores for cheap, good brand ones.. i think a lot of the dealers have switched over and gone china junk. Its a vital control valve, dont skimp out or over look it.