D5 (2005 on) How Cool (or Warm) is your D5 Diesel in Winter?

[SwissXC90]

I bought my MY2009 XC90 with a D5 diesel (185hp, Euro4, with silver engine cover) in March 2016. I experienced one snowstorm the week I bought it but then Spring came and it got warm.

I am now going through my first real Winter with it and would like to compare my engine coolant temperature with other D5 diesel owners.

I have the VolvoTech CanBus Extender (CFE), and can monitor my coolant temperature on the DIM digital display, to a resolution of 1°C.

I've noticed my D5 normaly runs at 87° to 89°C, only hits up to 92° when under more than normal load (like going up steep hills). It never overheats.

In Winter, the D5 will warm up faster than in Summer due to the CPM (Combustion Preheater Module) parking heater. But the coolant temperature will fluctuate, and go down when the engine is under light load.

Example:
Today, I started the engine in -13°C, after running the parking heater for 15min. The engine collant was preheated to +40C before starting, making starting very easy, thanks to the parking heater.

After start, we drove down off the mountain, meaning lots of downhill at around 50 to 70kmph (30 to 45mph), resulting in very little engine load. Gravity provided most of the motive power.
I turned the parking heater off when the D5 reached around 65°C.
However, monitoring the coolant, I saw it took a long time to reach 70°C and never got up to normal 88°C until I hit the flatlands and the engine had more load.

We went over the next range of hills: uphill, engine happy at 88°C. Downhill, engine cools down to around 70°C. It varies between 70° and 88° depending on the engine load. Ambient outside temperature was a steady -13°C.
The temperature gauge on the dash stayed at about the 'normal' half-way mark, just dropping a bit when at around 70°C. I take this as a deliberate decision from Volvo that the temperature gauge shows normal temperature at anywhere from 70° to 95° (I haven't ever seen it get higher), indicating that it is not unusual for the engine temperature to fluctuate.

I know modern diesels are so efficient that little waste heat results (compared to petrol engines), which is why the D5 is fitted with a fuel-burning auxilliary heater to help it warm up.

I am curious if the variations in coolant temperature I observe with my VolvoTech CFE are considered totally normal for a modern, efficient D5 diesel.
Or does it mean my thermostat is likely to be not closing fully, resulting in the engine cooling itself too much??

Please post your D5 Winter experiences here for some comparision.

PS: I know the UK D5 drivers often do not have the parking heater fitted.... so you would have longer warmup times than I experience.
With my parking heater, my engine reaches normal >80°C in 1.5km, after sitting in the garage overnight, which is about 5°C ambient, with coolant about 10°C.

[5cilinder]

Its normal that its a few degrees cooler under 90c under light load in the winter, notice in a hot summer it will be 90 c or even higher under load
Its also the reason they let the coolant dial in the exact middle between 75c and 105 to reassure , but with the obd readout you can see the fluctuations

But it shouldnt go to 70 degrees with a healthy thermostat , but when you go downhill in swiss for 10 minutes with fuelcutoff and the heater on it will extremely cool down

[yodacorp]

I have a 2004 D5 163hp with a new thermostat fitted a couple of weeks ago. I do have a heater which does not work right now...luckily there is info on this board and someone would point it out for me...
Now my engine heats up faster under load but T fluctuates even more than the fella above, it actually drops to about 50 when idling. No problem on highways, it cools down only when not loaded or idling. What is the deal with that? Second thermostat, oil thermostat?
The new one I installed is Gates TH35991.
Anyone care to share ideas? Thanx!

[5cilinder]

if your idling with cold weather and using your heatercore temperature will cool down
If it stays above 85c when driving it should be ok
Reverse is also true : idling in the summer without using the heater will raise temp to 100 c if you idle long enough

[tt82]

My D5 doesn't fluctuate anywhere near as much as that but it does alter by a couple of degrees depending on the gradient on the motorway. I do find that on the 50mph speed restricted areas, it will warm upto about 70 degrees and then it takes a long time to reach the 86-87 operating temp.

[SwissXC90]

Thanks everyone
My conclusion: my engine temperature behaviour is normal.

[5cilinder]

Originally Posted by tt82

My D5 doesn't fluctuate anywhere near as much as that but it does alter by a couple of degrees depending on the gradient on the motorway. I do find that on the 50mph speed restricted areas, it will warm upto about 70 degrees and then it takes a long time to reach the 86-87 operating temp.

The 70C will be reach relative faster due to the bypass valve wich bypasses partly the heatercore.
after 75c its completely closed and the heatercore is full flowing even if you dont use the heater during warmup the cold coolant from the heatercore and hoses will dilute the warmer coolant in the block and will drag the last temperature rise to operating temperature of nearly 90 c

[cheshired5]

Originally Posted by 5cilinder

The 70C will be reach relative faster due to the bypass valve wich bypasses partly the heatercore.
after 75c its completely closed and the heatercore is full flowing even if you dont use the heater during warmup the cold coolant from the heatercore and hoses will dilute the warmer coolant in the block and will drag the last temperature rise to operating temperature of nearly 90 c

The heater core receives full coolant flow at all times.

[5cilinder]

Not for the euro 4 engines according vida, look under design information

[cheshired5]

Originally Posted by 5cilinder

Not for the euro 4 engines according vida, look under design information

I have.
I suggest you read it again.