Technical What should be the coolant temp 1.3 m-jet?

[htevents]

Hello all,

In the Netherlands last week the temps where below zero degrees celsius and I noticed a coolant temp drop when driving slow/low revs. Let me explain:

I have Realdash and Torque Pro as diagnistics/extra gauges app. I can read coolant temp with the apps and I noticed the following:
- Normal acceleration and normal driving (80 km/h roads), coolant temp: between 74 (when deaccelerating/waiting a few seconds for a roundabout) and 79 (when normal driving), with peaks of 82 degrees when accelerating.
- Slow accelerating and slower driving (about 50 to 60 km/h), coolant temp: between 68 and 73 degrees, peaks of 76 degrees when accelerating more firm.
- City driving (about 30 to 50 km/h) not higher then 63 degrees.
note: temps are in celcius

With the first scenario, the temp gauge climbs up to the middle and stays there. With the second scenario, the temp gauge climbs to the middle and drops 1 bar of the gauge when temp drops below 70 degrees. With the last scenario, the gauge climbs up to about 2/6 of the gauge.

All temps where read with Torque Pro/Realdash (they show the same temps).

I heard the multijet doesn't generate a lot of heat, so this might be normal behavior, but the petrol car of my wife (Hyundai I20 2015) has running coolant temps of 90 degrees celcius. Is it correct that the Multijet enigne's have a nominal temp of around 79/80 degrees celcius? When outside temp is higher then 5 degrees celcius, it reads 79 degrees celcius steady. I do not know yet what the behavior is in temps above 20 degrees celcius.

I hope you can inform me a bit about this behavior.

 

[jackwhoo]

If you have had the heater on for the car interior , during you experiment then it is entirely possible that coolant temperature fluctuations are perfectly normal.
As you say the multijet diesel is very efficient and produces little waste heat.

 

[htevents]

If you have had the heater on for the car interior , during you experiment then it is entirely possible that coolant temperature fluctuations are perfectly normal.
As you say the multijet diesel is very efficient and produces little waste heat.

Thank you for your quick reply.

Yes the heater was on (very much on) and the temps became more steady when turning the heater off.

What I wanted to seek out with this question was mostly the nominal running temp of the engine (coolant temp). Are the read outs of the apps correctly like: is 79 degrees celsius the nominal temp of this type of engine or should the temp be higher, like I mentioned my wifes petrol car running coolant temps around 90 degrees celcius?

When the read out is around 79 degrees, the temp gauge of the car is in the middle position by the way.

 

[jackwhoo]

Thank you for your quick reply.

Yes the heater was on (very much on) and the temps became more steady when turning the heater off.

What I wanted to seek out with this question was mostly the nominal running temp of the engine (coolant temp). Are the read outs of the apps correctly like: is 79 degrees celsius the nominal temp of this type of engine or should the temp be higher, like I mentioned my wifes petrol car running coolant temps around 90 degrees celcius?

When the read out is around 79 degrees, the temp gauge of the car is in the middle position by the way.

Yes around 80 is common for your diesel.
Look up the thermostat on a part seller website and check the opening temperature to find out for sure.

 

[AndyRKett]

So when I had my old 1.3 which I had for years and in all weathers I found that the normal temp is about 87’C

In the cold weather we’ve been having it was perfectly normal for the temperature to drop below that and on one particularly cold trip to Yorkshire in 2009/10 in heavy snow the wipers froze, thinking I could heat some water off the top of the radiator I found the whole radiator was stone cold, basically the engine was keeping cool enough without the stat being open after a few hours of driving.

Later in around 2013 the water pump gasket went, again in very cold weather, I didn’t know it at the time but I had no coolant in the engine, I drove about 20 miles with absolutely no I’ll effects on the engine.

So in this cold weather it’s perfectly normal to see cold running temps.

As for the temp gauge, well fiat gauges are digital they give an idea but not an accurate reading, so when the needle is in the middle it’s telling you the engine temp is “normal” not any specific temperature, any movement from that is telling you something is either getting hot or cold, this is often the cause of many a failed head gasket, because by the time the car starts moving towards the hot, it’s already over heated and by the time someone stops the damage is done.

Many cars do things like this, as an example the fuel gauge on my golf scares you into getting fuel as the gauge drops rapidly once you get to the red zone the last segment going down to zero in about 10 miles while every other segment is worth maybe 50-60 miles of fuel

 

[htevents]

So when I had my old 1.3 which I had for years and in all weathers I found that the normal temp is about 87’C

In the cold weather we’ve been having it was perfectly normal for the temperature to drop below that and on one particularly cold trip to Yorkshire in 2009/10 in heavy snow the wipers froze, thinking I could heat some water off the top of the radiator I found the whole radiator was stone cold, basically the engine was keeping cool enough without the stat being open after a few hours of driving.

Later in around 2013 the water pump gasket went, again in very cold weather, I didn’t know it at the time but I had no coolant in the engine, I drove about 20 miles with absolutely no I’ll effects on the engine.

So in this cold weather it’s perfectly normal to see cold running temps.

As for the temp gauge, well fiat gauges are digital they give an idea but not an accurate reading, so when the needle is in the middle it’s telling you the engine temp is “normal” not any specific temperature, any movement from that is telling you something is either getting hot or cold, this is often the cause of many a failed head gasket, because by the time the car starts moving towards the hot, it’s already over heated and by the time someone stops the damage is done.

Many cars do things like this, as an example the fuel gauge on my golf scares you into getting fuel as the gauge drops rapidly once you get to the red zone the last segment going down to zero in about 10 miles while every other segment is worth maybe 50-60 miles of fuel

Thank you very much for your contribution.

 

[htevents]

Yes around 80 is common for your diesel.
Look up the thermostat on a part seller website and check the opening temperature to find out for sure.

Thank you. This is the answer I was looking for and in this case, I was hoping for haha.