coppermack

Just thought I'd update. Ended up being air in the system. Burped it and has been running fine

It was steaming pretty good when I pulled over.

Thanks. sure hoping for air in my system and not a blown gasket

I'm guessing you got some air in there when you changed out the thermostat, but then again I like engines with dual spark plugs so take what I say with a grain of salt........

Had a neighbor suggest that as well. What's the best way to "burp" it and check. Lol.

I've got a 94 ch613 with a mack 350. Truck ran hot on last trip (hauling grain 25 miles) and then all of the sudden ran cool and wouldn't even get above 120 or so. I assumed it was a sticky thermostat replaced thermostat. Next trip out this afternoon loaded truck (ran app. 1 hr before I hit the road) temp was around 130-150. Made it less than 5 miles and gauge was about to bump into the red. Pulled over, cooled off and came back to shop. Now I'm guessing water pump or maybe an air lock? Pretty terrible as a mechanic so any help appreciated. Thanks