Hello all I'm having an issues with my 8.9 ISL. Going down the road at cruise 67 mph I've noticed the engine temp steadily rising from about 185 to about 210 then watch it going back down to 185, This keeps happing. Temp. outside about 90 degress. Any Ideas?
Check the antifreeze.
See if it is good. Test it.
If it’s old or if the mixture isn’t correct you will have temperature issues.
I’m not sure what is recommended. But when I had my 2007 Ellipse my diesel guy always checked my antifreeze when he did my oil change. Once in a while it needed additional antifreeze. Once it tested out that the mixture was not correct and he added pure antifreeze to bring back to the correct testing level. I never understood what he did. But, if you antifreeze is old I would check it.
Climbing hills will up your engine temp, more so when it’s hot outside
Sounds like a sticky thermostat opening and closing. Also, do you have a power fan that engages and disengages? If it was the anti freeze why would it cool down and then heat up again. It would just get hot and stay there.
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2012 Journey 36M, Cummins 360hp, 2015 Ford Explorer Blue Ox, AF1
I would agree with the sticky thermostat and also possibly low antifreeze comments. How old is your engine? When most thermostats fail they fail in the too hot direction, but some fail in the too cool direction.
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