Did you have the climate control unit on during that period of engine braking?As I got asked by someone, I've done a video with the behavior of my car with the replaced thermostat that still has the issue.
Outside temperature: 65-68F
Start of the trip: 16151 miles (video starts after 1 mile of driving already)
End of the trip: 16162 miles
Total trip duration was 11 miles of driving on the back roads and the engine did not get to operating temperature. I stopped in between at a gas station and the road was uphill and downhill.
(needless to say the other car in the same conditions gets to operating temperature in 2 miles).
Please pay attention in the video at between 07:10 - 09:00 as you will see the temperature needle going down around there. (slight engine brake)
It will be interesting to see what your coolant temps are reading after they replace it with the newer part. I'm puzzled though why they need to send one of their techs, given that Mazda seems to have completely identified the problem and also the fix. Seems like all they should want to do is have the valve that's on your vehicle right now sent back to them, in order to confirm that it's defective as described in the TSB....This confirms that the thermostat that I got, was also the old type ...
To be honest, I have so far been very impressed by your efforts in gathering data, almost like how a test engineer would do...I've done the base measurement test with the current thermostat on a route that I can easily repeat after they will fix it.
I will redo the test once they will fix it and add new measurement on the same graph.
- Outside temperature: 70F (21C)
- Car was sitting in my garage at 80F (26C) (so best case scenario for my thermostat)
- Elevation gain: 500 feet (170m) in 0.7 miles (pretty steep climb going half throttle and plenty of opportunity for engine to warm up; on the graph is between 07:38 - 07:41 (if curious about the road, it's this one))
- Max speed: 50mph (80km/h)
- Trip duration: 13 minutes
- Trip distance: 5 miles
View attachment 283522
I have done the same road with my other car and here's how it looks (this is how I would expect Mazda temp to be as well)
View attachment 283525
My Mazda thermostat seems to be under 180F which would be in the range of Mazda's TSB as the say the following:
Verify customer concerns and check the coolant temperature in the freeze frame data.
- If it is at around 104-176 °F (40-80 °C), proceed to step 2.
In addition to the actuator that you mentioned, there is also a position sensor which monitors how much the actuator has opened the flap. So if the actual flap opening is not what the ECM commanded and is expecting, then an OBD code should be set and the CEL turned on. So if it was sticking, then the driver should become aware of it.I wonder if it's this little motor that bad. You can see where it plugs in. From what I read, it opens up to send coolant to different parts of the engine, where the coolant picks up heat. So if it were prone to get stuck, I could see a scenario where the coolant only gets distributed thru the engine to gather heat when the car is on an incline.
Thanks. Well, I'm an engineer (software) but that doesn't stop me from reading technical documentation in automotive; if there is a procedure, installation manual or in general any sort documentation, I will read it.To be honest, I have so far been very impressed by your efforts in gathering data, almost like how a test engineer would do...
It's def a wackadoo problem. I suppose you could park it on a steep incline and see if it gets up to operating temp and stays there while parked that way, but even that would provide limited insight. I do now agree this problem is potentially more serious than it first appears. For instance if the coolant is not getting hotter, then that might mean that the rest of the engine is getting hotter than it's supposed to, which would lead to faster degradation of engine parts.In addition to the actuator that you mentioned, there is also a position sensor which monitors how much the actuator has opened the flap. So if the actual flap opening is not what the ECM commanded and is expecting, then an OBD code should be set and the CEL turned on. So if it was sticking, then the driver should become aware of it.
Mazda did say in their latest TSB that the problem with the coolant valve is caused by 'hollow' areas produced during the manufacturing process. And the hollow areas cause the mechanical thermostat inside of the valve to see hot coolant sooner than it should and open prematurely, thereby keeping the system cooler longer that it was designed to be. Now that's what Mazda says, and although it sounds reasonable to me, no one outside of the Automaker's circle knows if all of that is correct, and if this is the complete story. Time will tell about that.
... My 2006 Mazda3 is like this also. I have found if I do a little more spirited shifting, the needle will move up. And it is fun.Normal for the 4th Gen to take a long time to heat up... bellow 0c it takes me around 15 min to get up to about middle of the gauge.. When i'm just driving in traffic around 50km/h..... If i'm on the hwy about 5min doing 100km/h with it bellow 0c outside... I know 3 other that have 4th gens and they act the same way... Nothing to worry about its normal..
According to Mazda, this issue a result of the internal mechanical thermostat opening earlier than it should be. And that means that coolant is flowing unrestricted throughout the entire system, which includes the engine. So there's no chance of the engine being too hot as a result of this coolant valve manufacturing defect, assuming everything is exactly as Mazda described in the TSB.... For instance if the coolant is not getting hotter, then that might mean that the rest of the engine is getting hotter than it's supposed to, which would lead to faster degradation of engine parts.