Those Big Horn Mountains really are something else.
So I began the eastward trek today. With full tank of 87 octane, I again started up into these mountains again on 16. The first part was again a serious grade but no signs to say what the percent was. This time I kept it in the 50mph range and never went much over 4k rpms. I didnt try to maintain speed and let it drop when it needed to. Luckily very little traffic and never really held anyone up. By maybe 5 miles up, I got the warning of the air conditioner being shut down because of engine heat and by this time the coolant was at 258⁰. Luckily I was already looking for a pullout and one was right there when this happened. I stopped and let it cool down. From then on, I just kept the AC off and opened the windows instead just to be safe. When I started off again, at times the coolant would get back to the 250⁰ range but then a couple down hill sections helped it cool down again. I was able to make it all the way to Buffalo without having to stop again. It mostly stayed in the 230⁰ range. Interestingly enough one of the longer flat runs, it actually cooled down to just under 180⁰. I thought that was a bit odd. That didn't happen on the way west.
Before I hit Buffalo, there was a sign that said there were 5 downhill grades of 8%. After that sign and the first downhill grade, there was another sign with the number of approching grades dropping. But it looks like that initial westward climb was 8%. I tried to calculate how long it was and it looked like maybe 5 miles or just over. So that did put the engine to a real test.
Based on what happened heading east, I don't think I can put the blame completely on the 85.5 octane I used the first time through. The first time through, I know I may have been going a little faster and running the rpms a lot higher for as long as I did. I didnt do that this second time. I know the trailer brakes weren't sticking because I have a TPMS system that also shows the temperature of each tire. All maintained roughly the same pressure and temp. And there was no smell or smoke coming from them. Same with truck tire pressure. All were about same and no smell or smoke. Not quite sure what to be looking at but sure seems like something is off.