Over Heating

[TheViking]

Hi guys,

This has probably been discussed numerous times.

I'm having some issues with my 2016 Ford fiesta St overheating every now and again. It has 66k miles on it. It seems to only happen in summer months and when the car is driven over long periods 3+ hours of driving. Sometimes it overheats and then 20 seconds later it goes back to normal. Without me having to stop and let it cool down. Sometimes It overheats immediately. It's very inconsistent. When i stop and rev up to 2000rpm with the heater on, temp gauge goes down.

Ford wants me to pay $300 for a diagnostics test. I've replaced the thermostat about 4 times already. The car still overheats. Ford diagnostic cant give out a mechanical fault only electrical. Diagnostic machine cant read a broken engine mount, can it? Didn't think so, so how can it tell me that the water pump is faulty. Their go-to is always thermostat. I think they are just trying to make money out of me.

I've pulled the little circulating pipe off the water bottle while the vehicle is running, only steam comes out, no water. This tells me it could very well be the water pump. I know the water pumps on these motors have plastic vanes that tend to wear. Im waiting for it to cool down, so i cant start it up and see if its circulating coolant.

Alternatively, it could also be the temp sender unit. these have two, one by the thermostat and one on the engine block.

Obviously, I've checked coolant levels and pressure in pipes. I don't think there's a blockage. Has anyone dealt with this before? I know its hot in SoCal. but that shouldn't affect it that much.

I don't agree with having to change the intercooler. I want to keep the vehicle as stock as possible. Personal preference.

Any input would be greatly appreciated. Is there something I'm overlooking?



Have a great day all.

 

[rcarbajal4]

I also live in LA with a 2016 model, and I can tell you the heat here is definitely more than enough to overheat this little car. I would over heat every summer until just recently when I upgraded to the 180° thermostat with mountune radiator. Even at stock power levels the stock radiator and intercooler struggle to keep temps down.

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[TheViking]

So is there a solution to this problem, without having to put upgraded parts into it? Just personal preference, I like to keep cars, the way they come from the factory.

 

[jmrtsus]

Was the recall required on your car? I think some '16's were.

 

[TheViking]

Was the recall required on your car? I think some '16's were.

That's a negative sir.

 

[rcarbajal4]

You could try a 70/30 water mix along with putting it in eco mode in the hot months. Other than that I don't see much else you could do, as even that didn't seem to help me in the summer.

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[Philld_with_donuts]

I would second increasing the water content in your coolant if you're going to consider straying from factory.
Water cools significantly better than coolant, but it obviously doesn't offer the same freezing or corrosion resistance.

There are plenty of vehicles running 100% distilled water with things like water wetter to help manage corrosion protection, but if you go this route you need to mindful of the lower boiling point of water opposed to the coolant. And also switch out prior to winter (if it freezes there).

The fact that it's very inconsistent sounds to me almost like trapped air in your coolant circuit. Although if you've swapped so many parts already, surely you would have purged any air somewhere in that process.

I'm not the most fluent in our coolant circuits, but usually that little pipe connected to the hot bottle should be venting air and vapors out of the system.
I wouldn't expect coolant to be circulating through that line. That line also helps keep positive pressure in the bottle and feed coolant out the bottom back into the radiator.

I would also expect the overheating to be very consistent if you had broken blades on your water pump. If the pump wasn't circulating properly, your overheat would happen consistently early in your drive cycle, and would continue to happen in regular intervals. (Unless we have one of those fancy variable displacement pumps. I'm assuming it's linear though...)


....



This might sound a bit extreme, but is it possible that you have a very very small leak in your cylinder head gasket? Or a very small crack in your block?

The dealer should be able to test your coolant for the presence of exhaust gas, and I think there are also kits to test it yourself.

In other applications, I have seen very small cracks weep exhaust into the coolant circuits and create excessive aeration. This air will do very strange things in the coolant system, like set faults for thermostats opening late, or overheat the engine because the thermostat didn't open on time. It will also be very irregular as these bubbles shift and move through the coolant circuit.

The irregularity in the overheating makes me think this might be possible here.

 

[jmrtsus]

Before I spend money at the stealership I would try to find a good independent shop. The only thing I trust a stealership to do is steal your money. Then wait for to to come back so they can do it again! An independent shop does not have guaranteed warranty work and needs customers to be happy and come back and give referrals. I am lucky that my "guy" in the local Goodyear dealer and any work done is warranted at any Goodyear store if I am on the road. Not that I have ever needed it, LOL. They know me and my wife by name and the Asst. Manager is as anal about his cars as we are ours, he understands. Ask local car nuts who they trust to find one.

 

[spedy7]

Radiator! It's stupid, but I've done a few and for whatever reason it seems the factory radiators are easily clogged from debris or slugged coolant (rumor is, this is from radiator assembly). Best to go with a Mishimoto or Moutune radiator, but a new OEM will fix it for a while (as long as everything else checks out).

 

[TheViking]

I would second increasing the water content in your coolant if you're going to consider straying from factory.
Water cools significantly better than coolant, but it obviously doesn't offer the same freezing or corrosion resistance.

There are plenty of vehicles running 100% distilled water with things like water wetter to help manage corrosion protection, but if you go this route you need to mindful of the lower boiling point of water opposed to the coolant. And also switch out prior to winter (if it freezes there).

The fact that it's very inconsistent sounds to me almost like trapped air in your coolant circuit. Although if you've swapped so many parts already, surely you would have purged any air somewhere in that process.

I'm not the most fluent in our coolant circuits, but usually that little pipe connected to the hot bottle should be venting air and vapors out of the system.
I wouldn't expect coolant to be circulating through that line. That line also helps keep positive pressure in the bottle and feed coolant out the bottom back into the radiator.

I would also expect the overheating to be very consistent if you had broken blades on your water pump. If the pump wasn't circulating properly, your overheat would happen consistently early in your drive cycle, and would continue to happen in regular intervals. (Unless we have one of those fancy variable displacement pumps. I'm assuming it's linear though...)


....



This might sound a bit extreme, but is it possible that you have a very very small leak in your cylinder head gasket? Or a very small crack in your block?

The dealer should be able to test your coolant for the presence of exhaust gas, and I think there are also kits to test it yourself.

In other applications, I have seen very small cracks weep exhaust into the coolant circuits and create excessive aeration. This air will do very strange things in the coolant system, like set faults for thermostats opening late, or overheat the engine because the thermostat didn't open on time. It will also be very irregular as these bubbles shift and move through the coolant circuit.

The irregularity in the overheating makes me think this might be possible here.

So as far as I understand its the return line or a self bleeding system should I rather say. So if the air is coming through that, that means I could very well have an airlock somewhere. I've bled the system now, water is coming through the little pipe. This gives me confidence in the water pump as well, otherwise there wouldn't be water pressure. So I think its either a thermostat has gone wrong or a faulty sensor. If there was a blockage in the system, I would not be able to bleed the system.

It ran up to about 210 degrees and then the fan switched on. I switched AC on, temps climbed to 230. At that point, I put the revs up to about 2000 holding it there. Fan speed increased, temps came back down to 210. No overheating at this moment. Diagnostic tool
not throwing any errors either.

 

[TheViking]

So as far as I understand its the return line or a self bleeding system should I rather say. So if the air is coming through that, that means I could very well have an airlock somewhere. I've bled the system now, water is coming through the little pipe. This gives me confidence in the water pump as well, otherwise there wouldn't be water pressure. So I think its either a thermostat has gone wrong or a faulty sensor. If there was a blockage in the system, I would not be able to bleed the system.

It ran up to about 210 degrees and then the fan switched on. I switched AC on, temps climbed to 230. At that point, I put the revs up to about 2000 holding it there. Fan speed increased, temps came back down to 210. No overheating at this moment. Diagnostic tool
not throwing any errors either.

Blown head gasket could very well be the case, although I don't have a loss in power. I guess a very small leak could be the result if i still have power. Will check the oil and see if there's any water in the oil.

 

[M-Sport fan]

The temps should have dropped when you first switched on the AC, yes, even in torrid L.A., since that is supposed to instantaneously kick on the HIGH SPEED fan setting (the added heat from the extra load on the engine from the compressor, and the heat radiated into the radiator from the condenser would yes, eventually overcome the cooling capability of that fan speed anyway over time, but not in the short term).

I would also check out your high speed fan relay as well.

 

[scooter123]

The plain truth is the automakers ALL tend to put in radiators that just barely provide enough cooling when the car is brand spanking new. As someone who has been hot rodding since the early 70's I'll tell you that one of the "secret weapons" for building a reliable street fighter was to install a larger capacity radiator. Because it doesn't matter if it has the latest fuel injection and turbo or a boatload of cubic inches and a carb a properly cooled engine will always beat an engine on the borderline of overheating. It's why one of the first items I ordered for my 2019 FiST was a Mountune radiator. Being they are a bit of a PITA to install compared to in intercooler all those other bits were installed within 4 weeks of purchase of the car and it took nearly a year to put the radiator in but it was well worth it. One unexpected benefit was in increase in my fuel economy by a whopping 10%, yeah the city driving mileage went from 30 mpg to 33 mpg. As for overheating issues, my timing was perfect. Because I put the radiator in during the beer virus lockdown and recently we've had a bit of a heat wave here in Detroit with temps making it to the mid 90's. In all that heat I have NEVER seen the temp indicator ever go over 4 bars. Contrast that with last summer when 5 and occasionally 6 bars was common with temps only in the 80's.

BTW, my other hot rod is a 1985 Monte Carlos SS with a GMPP HT383 under the hood. Put it together and used it to tow 5200 lbs. of boat and trailer at an average of 68 mph for a 700 mile drive to Lake George, NY. Cooling is provided by a Nascar sized BeCool aluminum 2 row radiator with a 180 degree thermostat in the engine. On that drive you could actually see the thermostat cycle, temps would drift up to 180 and the thermostat would open and the temp would drop to 160 in about 40 seconds, then it would slowly climb for 4 minutes or so till it hit 180 and the cycle would repeat.

Sum it up and you can spend about 650 dollars to have your dealer install a new Ford radiator and continue to have this constant battle with overheating or you can bite the bullet and install a Mountune 3 pass radiator. BTW the difference in sizing is the thickness, the Mountune is about 5/8 inch thicker so the fan shroud will be a bit closer to the engine. That is NOT a big deal, you wouldn't even notice it if you didn't actually look for it. As for installation it uses the exact same mounts as the factory radiator and fits perfectly. One other benefit is it is 100% Aluminum, so no plastic tanks to crack when you're out in the middle of nowhere with no repair shop in sight.

 

[spedy7]

The temps should have dropped when you first switched on the AC, yes, even in torrid L.A., since that is supposed to instantaneously kick on the HIGH SPEED fan setting (the added heat from the extra load on the engine from the compressor, and the heat radiated into the radiator from the condenser would yes, eventually overcome the cooling capability of that fan speed anyway over time, but not in the short term).

I would also check out your high speed fan relay as well.

I used to think the same until I retrofit a/c into my '66 Mustang with a stock size 2 core aluminum radiator. Poor thing overheats like mad with the a/c on in the dead of summer (eventually dropping a larger radiator in). All the condenser is is another heat exchanger, another 120*+ in front of the radiator. As for the fans, there's only one relay for the 1.6 EB, R50 in the BJB. The fan speed is controlled by the cooling fan module (silver thing on the fan shroud) and PCM.

The best option is to just swap in a new aluminum radiator (proven by many members, it works). The radiators in these things are super thin (single-core I believe) to have a stacked condenser AND intercooler in front of it with only one small fan to pull air at a stop.