MaxxForce 7-anti freeze smell on long pull

[G.Greenwood]

I have a 2011 Thor Serranno 33A- MaxxForce 7 with 25000 miles. On a long (3-5 mile) 5 percent uphill grade pulling my trailer I can occasionally smell what I think is anti freeze. One one occasion this spring (10 miles uphill on a 6 percent grade) the temperature rose to the red light point for a few seconds then went out and the temperature started to drop again. I was at the top of the grade. The anti freeze level doesn't appear to go down. This "smell" on a long pull has occurred since I purchased the unit new in 2011. Has any one encountered this situation - any thoughts on the source of the problem?
Thanks.

[cb1000rider]

Haven't encountered it in that vehicle, but you've got good instincts. That smell is most likely a leak somewhere. I'd mark my current coolant level and after a few drives check it again. My guess is that you have a leak under pressure and it could be found by a shop that can pressurize and check the cooling system. Might be as simple as a hose clamp.

[Dtwallace]

I wonder if you are actually smelling an exhaust leak?????

Or the heated metal from the turbocharger as you're making those long pulls. Since you don't see a drop in coolant level, that would be my best guess.

DTW

[Denniscw]

Have a 31X never had an anti freeze smell. I would go to an auto parts store and borrow a coolant tester. It replaces the radiator cap, has a gage and a pump.