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

[5cilinder]

Originally Posted by tt82

This morning my commute was a 35 mile mostly motorway journey. About 10 miles in there is a slight downhill gradient about a mile long. With the cruise set at 65mph, my coolant temp dropped from 80 to 76 dergrees C.

80 under highway load even in the winter is too low .check your thermostat

[tt82]

Originally Posted by SwissXC90

At what outside ambient temperature?

About -2 to 0 degree C

Originally Posted by 5cilinder

80 under highway load even in the winter is too low .check your thermostat

It got up to 86/87 degrees C a few miles later and stayed there for the rest of the journey, the thermostat is fine. It's just at that point in the journey, it had only reached 80 degrees C.

On a separate note, I find it warms up to 70 quite quickly, but takes it time to climb the last few degrees C to running temperature.

[5cilinder]

Then its fine
The reason for slower rate of the last warming degrees is of the bypass valve and releasing colder coolant wich was holded back in the beginning to speed up the early warming , i posted a explanation from the documentation in this thread

[Ahtif]

Any ideas what to do next. I've changed thermostat second time. This time with housing (wahler product). Still same temp, after 30 mile trip, around 70C. Dealer hasn't any ideas.

[Munro83]

Coolant temp sensor?

My 2009 v70 doesn't have a temp gauge which I find a bit unnerving

[5cilinder]

Do a torque obd readout with cheap elm237 bluetooth adapter

[Ahtif]

Temp sensor is also new one. And I do not have also temp indicator but I'll use simple elm327 device with my phone.

Is there any other valve which directs warm coolant into the radiator? It takes 2-3 km to warm up to 50C, then around 15 km up to 60C and if it is lucky day then after 30 km it will reach 70C (ambient temp 0C).

I tested new wahler thermostat in hot water pan and it opened at 89C, so it is ok.

[SwissXC90]

Is it a D5 diesel?
Do you have a CPM preheater fitted? (CPM = Combustion Preheater Module)
Is the preheater working OK? Check in VIDA.

If you have a preheater, you'll have a warning sticker inside the fuel filler lid, and one in the engine bay on the left underside of the bonnet

On cold days with ambient temperature around 5°C or lower, my preheater will switch on to help the D5 diesel reach operating temperature faster. My D5 will reach 70°C to 80°C in around 2km of driving under moderate load and with the interior cabin fan off. Turning on the cabin fan slows down the engine warmup time.
I also get into the habit of starting the preheater on cold days before I use the car: on Sunday I was our sledding with friends and managed to turn on the preheater from a distance of 120m via the remote control at the end of the day when we were packing up. Ambient temp was 0°C and the coolant had reached around 60°C by the time I needed to start the engine. And the cabin was warm .

You know when the preheater is running if you start the engine when ambient temperature is <5°C, let it idle for a few minutes, and then observe (hear, smell, feel) the preheater combustion fan running, and the preheater exhaust gasses being omitted from the left front of the vehicle: in front of the front wheel, between bumper and front wheel.

[Ahtif]

Thanks for the input, but I do not have preheater.

And yes, it's a D5 engine (D5244T10). I have read that even without preheater, engine temp should be above 80C.

I'm afraid, if engine temp is so low, then DPF burning procedure won't start at all, even though I drive 90 km per day (only extra urban).

Something is not right, dealer suggested to replace thermostat, but it's done.

[5cilinder]

If thermostat is ok does it seat right in the housing? ,did you verify that the temperature given by the sensor is right? by infrared measurement?

The bypass valve only varies the coolant flow in the short circuit (even if it is defect it wont let coolant trough to the big radiator only the thermostat does that