I am using the Android TORQUE Pro app on a smart phone.

https://play.google.com/store/apps/d...l.torque&hl=en

It reads the ECM processed sensor signal and deliverers data to the OBDII data port as a digital signal translated by the software into degrees C. It directly reads the ups and downs of the thermostat/water pump/fans controlled system temperature in one degree increments. At the moment mine is reading 96*C nominally. It will drop a degree or two at highway speed, rise a degree or two sitting in traffic.

I think that the new sensor is out of specifications and is reporting too high a temperature. Negotiating to replace the sensor.

 

I agree with your diagnosis. And thanks for the other details. I like all that I am picking up here and there.

 

Solution still under evaluation.At <84C my OBD throws a P0128 which disappears once the temperature goes above. Temperatures fall when I sit in traffic for extended periods and continue to rise when I get back on the move.




While driving in traffic the coolant flow through the radiator is slower and gives off more heat because it is in contact with the cooling airstream longer. This of course is based on the cooling fans operating to add to the total air flow. As you drive faster the water pump pushes the coolant through the radiator faster and heat transfer coefficient suffers. True you will dissipate more total heat but you are also generating more heat as the engine load is increased. The flow through the block is turbulent, it is also slower due to the larger volume and passageways in the block. The narrow and straight passageways in the radiator are more laminar and therefore less turbulent. When you install a more efficient radiator it has a larger volume as compared to the stock unit, which allows for a slower flow rate. Maybe a 4 row in place of a 3 row core, and maybe a larger face area as well. All of which increases the volume in the radiator so for a given gpm the velocity is slower. The balance point is the acceptable temperature range the cooling system operates in. The lower end of the range is the thermostat rating point, the upper end is something less than the boiling point of the coolant mixture under pressure as determined by the pressure rating of the expansion tank’s cap.


PS: the cooling system interior and exterior surfaces needs to be clean so the heat transfer coefficient remains at it's peak. Just look at what builds up between the air condensing condensing coil and the radiator to cause the engine to run hotter.

 

AJ, the temp drops when stuck in traffic once the fans are running.

And the P0128 occurs because you don't have a working tst so the car doesn't warm up fast enough. No smog laws where you live? The rapid warmup is an emission feature.

 

Thanks Ronald,
Lemme throw a link here I have found on that code. This one: OBD-II Trouble Code: P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

It looks like that definition also throws in another spanner in the works namely, the in-take air-temperature. To this extent, I would assume, ambient/climatic conditions also may play a role? What do you think?

I understand your exposition on the laminar vs turbulent flow dynamics. I guess the radiator indeed presents a very efficient heat transfer system as it causes noticeable temperature drops in the fluid in such a short time. What bothers me however is how the engine would then achieve some kind of "steady-state" temperature if the flow were perpetually turbulent. Left to itself at idle, the engine temperature seems to hold a consistent reading until, under movement, it is asked to release more power and the detonation sequence gets modified. To that extent, I am finding trouble understanding the notion of wholly turbulent flow in the engine. However, if the water pump speed varies, perhaps that would click in my head. So does the water pump speed remain the same or it does vary at random under different circumstances (or is there a pattern)?

Okay. I just found this below and quote verbatim (source: http://www.academia.edu/4569540/****...FICANCE_OF_ITS)

"A common misconception about cooling systems is that if the coolant flows too quickly through the system, it will not have time to cool properly. Because automotive cooling systems are close loop, coolant allowed to stay in the radiator longer will also stay in the engine block longer producing increased coolant temperatures. This can easily lead to ‘hot spots’ and ultimately engine failure. To avoid these centrifugal pump increases velocity by reducing pressure with providing sudden reduction in cross section area at outlet of pump. Sudden reduction also result into turbulent flow at the outlet which contradictory helps in maintaining engine block temperatures which can see through above results also. However turbulent flow at the inlet leads to less pump efficiency and also if pressure falls below vapour pressure of coolant then it leads to pump cavitation. From above results we can conclude that venture effect at the inlet of the pump helps in avoiding cavitation by increasing inlet fluid pressure above vapor pressure at normal speed and decreasing velocity of fluid.”

I believe I understand it now and it seems to agree with many of your observations Ronald.

 

Thanks! We do have environmental laws but none of that classification. I am carefully keeping track of my OBD values for the period I have no tstat. I have a hope this will not be a costly experiment.