Engine Temps

Trying to decide if I should put a new thermostat in, with how cold it has been the last week the temp gauge usually sits at 70C. All my driving is on open country roads at 80km/h just cruising and the only time it will go over 70 is if I go up some hills. I know a diesel with low loads doesn't generate much heat so I am debating is it a thermostat opening too early or I am simply not burning enough fuel

I have an ultragauge on my car and a winter front. With the raft of cold, near 0F weather we’ve been having I notice that my temp rarely gets to 190F (normal) anymore. I live in rolling hill country, it heats up to say 170-190 going up hill and cools off to 140-160 going down the other side.

If I thought a new thermostat would allow it to reach 190 and stay there I’d change it, but I don’t think it would make any difference till the weather moderates or spring gets here. It’s just the nature of the beast.

You’re using plenty of fuel my mileage has fallen from around 52-53 to 45-47 if you track yours like I do you’ll notice an increase in fuel consumption simply because your car like mine is not reaching optimal temperature and when it does it’s not for long.

In the winter I always block up the lower grill. I buy the 1/2 pipe insulation that you wrap around copper pipes and cut it to fit. It holds in place with no additional adhesives.

If yo drive more than 10 minutes on country or highway roads the coolant gauge should go up to the middle. If it doesn't the thermostat needs changing. My '06 has this problem and it has an old thermostat but the '05 warms up without any problem since the thermostat was changed a couple years ago.

Unless it's extremely cold, the coolant gauge should always get to the middle if you're driving a decent amount at faster speeds, and even then the middle doesn't mean 90 degress. In my old MK4 90 was anywhere from 74 to 100 degrees... I only knew I had a bad thermostat because of my scanguage

The cabin heat will tell you if the thermostat is stuck open or not.

Here's my free winter front

Last week in -25c doing around 80-90 kmh it would still get up to the middle. That is with EGR delete and without a blocked off radiator.

$25 for a new thermostat and you should be all set unless it's your coolant temperature sensor.