Dear Forum members

I am a new member from Hungary and would like to ask for your help and experience. I drive a 2022 Smax hybrid as a company car. This is my first winter with the car therefore. I used to drive a 2.0 Tdci Smax for four years and also a Toyota RAV4 hybrid for four years before this car.

The challenge I have with this smax is around the coolant temperature or its display. I started to experience this once temperature got below 5 c° last October. I have a daily commute which is 30-35 minutes one way.

On my way to work (we use km, trying to convert to miles correctly), I would drive (section 1) 3 miles with max 30 miles/hour, then (section 2) 7 miles with 50-60 miles/hour, then (section 3) 5 more miles with again max 30 miles/hour. This last section 3 often starts with a complete standstill. I attach a picture of the display for the coolant. When I start the commute under 5 c°, by the time I complete section 2, temp meter would move out of the blue area. It would not reach the middle of the period between blue and red, but it would go 1/4 - 1/3 of the full scale. When I start section 3, it will very rapidly go back to the blue section, and it will stay there. Where in blue depends on traffic and temperature. The picture was taken after completing section 3 after driving 35 minutes.

On the way back, it is something similar, but outside temperature is typically a few c° higher. After section 3, it will reach the top of the blue section. Then it frequently goes until the middle of the scale, and then it typically doesn’t drop back to blue.

What I have found is that under roughly 5 c° coolant temp highly depends on the rev of the engine. Since there is no manual option to control rev on this type, I do not have any influence on this with the speed limit. Once the rev can get to around 2000 rpm, it will start to raise the coolant display. But as long as it stays in the 0-1500 range (as it typically would when not driving more than 30 miles/hour) the coolant display will not really get out of the blue, and also it will rapidly drop back there.

The car was in the service, they exchanged the full thermostat unit and also they applied full software update for the engine control twice. The situation is the same. As per the latest communication from Ford, the behavior described above is not considered as abnormal behavior by them.

I am still puzzled by this though. I never had a car that ended up in the cool section after driving it for 30-35 minutes. I have no problems with heating, though the increase in fuel consumption is somewhat higher with this car during winter than with my previous cars.

What is you opinion? Would you consider this normal or not? I am not 100% sure whether this is just the display, or the actual coolant temp. Since I don’t own the car, I have limited ways to influence what happens next, however I am worried that this is not normal behavior. This started in last October, and I didn't have this issue with the higher temperatures, the gauge went to the middle of the scale pretty soon, like 10 minutes and stayed there.

IF the gauge is displaying the coolant temperature correctly, then that is NOT normal behaviour.  

I would have said that the thermostat is stuck open - you have exactly the same symptoms that I had when mine was stuck open. But you've had a new one fitted, apparently.  But I wonder... if your Ford dealer now says this current behaviour is normal (which it absolutely isn't), do they actually know how to change a thermostat/did they actually change it? And from a logical point of view, if they say that the behaviour is normal, why did they change the thermostat (presumably at a cost to Ford under warranty)???

19 hours ago, alanfp said:

IF the gauge is displaying the coolant temperature correctly, then that is NOT normal behaviour.  

I would have said that the thermostat is stuck open - you have exactly the same symptoms that I had when mine was stuck open. But you've had a new one fitted, apparently.  But I wonder... if your Ford dealer now says this current behaviour is normal (which it absolutely isn't), do they actually know how to change a thermostat/did they actually change it? And from a logical point of view, if they say that the behaviour is normal, why did they change the thermostat (presumably at a cost to Ford under warranty)???

Thanks a lot for your thoughts!

Helpful and logical. I would assume they actually changed the thermostat, as the car was with them for two weeks and I was told the replacement part came from Germany. But as I don't own the car, I only know what fleet management tells me, and I don't get to see the work order, and as it was under warranty, there's no invoice I could check.

I also do not know at which point the region's Ford HQ was consulted by the Ford dealer. As I understand the "no abnormal behaviour" finally came from the HQ and not the dealer. Also I am not allowed to take the car to a different service on my own. And the company would not send the car for another round as Ford said it's normal. But I strongly feel this is not normal, assuming the gauge display is correct (which I believe is correct, because starting from about 10 c° it really behaves again like gauges in my previous cars).

I have a few more ideas, like measuring coolant temp once arriving to office, and as the weather will improve in the next few weeks, I will try to find some other clues.

I will also try to go back to fleet management based on the logical arguments you shared and get a statement from Ford HQ with regards to the temp at the top of blue section.

Also I am wondering if there is any service mode or display so that I could get to see the actual coolant temp as measured by the car. Then I could cross-check it with the manual measurement and determine if the gauge display is correct or not and what temp belongs to the right of the blue section.

Something is clearly odd, like the pieces somehow not fitting together, maybe the coolant is "too powerful", or some sensor or software doesn't take outside temperature and RPM well into consolidation. Or the control over-optimizes somehow. I assume (but maybe I am wrong) that if the thermostat were faulty, I would have temp dropping driving constant 50 miles per hour at a constant 2000 RPM, but I don't. It drops when it's colder and I do not have rev (<= 1500 RPM).

It was 0° c this morning. Temp gauge went to the midpoint of the full scale in 13 minutes. Hit the usual jam at 14-15 minutes. Engine stops and temp back in the middle of the blue section at 19 minutes. Engine starts at the left of the blue section at 23 minutes to 1200-1300 RPM (in even colder weather it would do 1600 RPM). Engine stops again at 25 minutes with temp in the middle of the blue section then starts and stops a few time. I arrive at 36 minutes with temp gauge in the right side of the blue section.

It is really like that control would only start the combustion engine if it really must (i.e. electric engine cannot cope or temp at left of blue). But the car somehow completely disregards coolant temp in this process other then starting the engine when temp hits left of blue. And nor the Tdci smax with start and stop nor the similar hybrid RAV4 behaved like that. There was no RPM meter in the RAV4, but (judging by ear) the similar hybrid RAV4 used higher RPMs in general. Even when the engine is running, the hybrid smax uses low RPMs, RPMs comparable to a diesel engine (i.e. 1300-ish with 30 miles per hour). Only when wind resistance requires a higher RPM to maintain speed (1600-ish with 40 mph and 2000-ish with 60 mph) it will raise rev. And coolant temp seems to correlate with rev.

Thanks again, sorry for the long post, and would appreciate any other thoughts.

On 2/28/2023 at 10:11 AM, gerilege said:

It was 0° c this morning. Temp gauge went to the midpoint of the full scale in 13 minutes.

That sounds like good, normal behaviour.  I wonder if there is an intermittent fault, perhaps.

 

On 2/28/2023 at 10:11 AM, gerilege said:

Also I am wondering if there is any service mode or display so that I could get to see the actual coolant temp as measured by the car.

I do not know your model well, but on most Fords, press and HOLD the OK button on the steering wheel and THEN turn on the ignition while still pressing the OK button. After a few seconds that should display a 'test' menu on the dashboard that you can scroll up and down. This should tell you if there is a difference between the sensor value and the visible gauge, so it might help.

 

Also, on SOME Fords I think there are two thermostats. Main one and another separate one for the oil cooler, so maybe that secondary one is faulty (if you do have that).

I have the same issue this winter. I borrowed an OBU reader from my colleague, and was able to record live data via a mobile application.

The data reflects what I experienced and is also in sync with what is displayed on the gauge. I also checked the hose temperature (where it comes out of the engine, roughly, by hand after I stopped) and I think the data read and displayed is correct.

The left edge of the blue section represents 50 Celsius, while the right edge 60 Celsius. The midpoint of the temp gauge is around 85-90 Celsius.

I recorded RPM and coolant temp. The idle RPM is 1250 during winter. First I drove about 20 minutes on flat terrain with a speed of 30 mph with very little traffic. Outside temperature was 5 Celsius, and I had the heating set to 21.5 Celsius. Under such driving conditions the engine would be either turned off (driving electric) or stay in the 1250-1500 RPM range, with a few occasional spikes to 1700-2000 RPM during re-acceleration after some traffic.

After start, the engine will turn on and remain on until coolant temp reaches 60 Celsius (right edge of blue). After that the engine will turn off and on based on the electric cell status or dynamic acceleration. Under the above conditions, the maximum coolant temperature was 65 Celsius. When the electric engine is in use, the coolant would drop back to 60 Celsius after 1-2 minutes, and would continue to drop (in electric or in traffic jam) back to 50 Celsius. At that point the engine would start again and operate until 60c coolant temp.

Then I switched to a different road where one can drive relatively smoothly with 45 mph. Everything else was the same. Under those conditions the car would stay in the 1250-1800 range, but mostly around 1500-1600 RPM. Coolant temp would increase to 70 Celsius in 2 minutes and 75 Celsius in 3 minutes, and would get close to the midpoint without reaching it. If I slow down again, same issue, coolant goes back to 60.

If I switch off heating completely, coolant gets and stays warmer quicker, and is above about 5-10 Celsius higher - compared to when it is on - under the same conditions.

As I wrote earlier, if I can get to 55-60 mph, rpm would be in the 1800-2000 range, and the coolant would stay midpoint with 85 Celsius.

So for me it looks like the car is simply not producing enough heat once the temperature drops to around 5 Celsius under the conditions described above. The car is able to heat, the car can be driven, it will simply choose to operate with RPMs (0-1500 mostly) that produce 50-65 Celsius coolant temp with heating if speed is not over 30 mph.

Coolant temp with this type does not seem to depend on the distance traveled. It only depends on acceleration dynamics and speed.

As I mentioned, the car was at the dealer two times, and finally Ford HQ released the car as not abnormal and the lessor will not pursue it any further. So this post is to report back about my experiences with the community. I will also report back for the cruise control issue.

Adding screenshots, the first one is half of the longer drive with 30 and the one with 45. The second one shot shows what happens when switching the heating on and off, the third one is about flat terrain (first half) versus non-flat terrain (second half).

Edited January 25, 20242 yr by gerilege
Adding screenshots