Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

2013 ford fusion

My cars thermostat runs normal all the time unless I go up hill. I drive into the mountains to work every day. It runs about 80% hot until I crest the mountain and then immediately cools back down to normal. Since its winter no air conditioning running but heat is on at times. Has anyone experienced this before. Only 37000 miles on car. Automatic transmission. Would love to hear your feedback

I’d check for a blockage on the radiator (like a bag or something), or maybe it’s a thermostat not opening completely. Have you checked the coolant level in the overflow tank?

Instead of “thermostat”, I am going to assume that you are referring to the temperature gauge on your instrument panel.

The first thing that I would suggest that you check is the level of coolant in the radiator. Make sure that the engine is stone-cold before removing the radiator cap, and then see if the coolant level is right up to the bottom of the radiator’s filler neck. If not, then top it off with coolant of the correct specification. Your Owner’s Manual will have info on the coolant spec., but if you have any doubts about what type of coolant to get, simply go to the parts counter at a Ford dealership.

If it turns out that the coolant level was low, then it is time to visit a mechanic so that he can find out where it is leaking.

If the coolant level is normal, then my next suspect would be the radiator’s cooling fan(s).
Make sure that you can see and hear them running when the engine gets hot.

You may have dead bugs or other debris in the honeycomb of the radiator. Take an air hose or a garden hose with a,nozzle and from the engine side out, blow out the bugs and debris.

As a temporary measure, turn the heater on full when going up that hill, that adds cooling to the engine.

You might try shifting into a lower gear which will increase the engine rpms and throw more coolant against the cylinder walls. That should drop the temperature.

As BR says above, turning on the heater should help keep the engine cool beyond what the radiator can do. So definitely use the heater as much as you like as using it cools the engine.

All of the above guesses are good and worth considering. Check those first. Besides those also consider a faulty thermostat or a cooling system that isn’t holding pressure to spec, possibly due to a faulty radiator cap. Checking for a faulty radiator cap most any shop can do easily, but there isn’t really any good way to check a thermostat other than removing it and testing it in a pan of hot water on the stove. If you had work done involving the cooling system just before all this started to happen the cooling system may have got air into it, that’s another guess worth considering. Best of luck.


When talking about an engine issue you should mention which engine you have.
I see that some 1.6L 2013 Fusion and Escape models are under recall for overheating.

Are you sure it has to do with mountain driving? Could it be that when you head up into the mountains there is an ambient temperature drop, too?
Other 2013 Fusion vehicles that have the 1.6L GTDI engine are subject to intermittent overheating in cold ambient temperatures (below 10F). Ford has a Technical Service Bulletin written to help their technicians diagnose and remedy the situation. Some remedies include reprogramming the engine computer and/or replacing the Coolant Bypass Solenoid Valve.

Do you have a 1.6L engine? I’d check this out with a Ford dealer.

CSA has some great ideas, pursue them with the Ford dealer.

I had an odd problem with my '83 GTI, it would overheat in the winter (in Anchorage!). Couldn’t find a problem, finally replaced the thermostat and found the casting was defective: the bypass outlet (that allowed a small flow of water to heat up the thermostat) was covered with ‘flash’. Removed it, no more problem.