Engine Not Reaching Operating Temp After 20km

Hello, I drove the same route today, as I have for years, which is 20 km long. But today, the engine didn't even warm up until I got home. When I was driving downhill, the temperature dropped from 70 to 65 degrees. The temperature was about 0.5 degrees below normal. Recently, when it was plus 5 degrees, I noticed something similar when I drove across the city and then back home, which was about 15 km. But the engine didn't even get properly warm, even though I wasn't driving defensively. What could be the cause?


cu moby

Good morning.

That sounds like a faulty thermostat to me.

It would also be interesting to know whether the temperature is actually not being reached or maintained, or if it's simply a display error.

Greetings.

Maybe that's because you're driving a diesel?

Our Galaxy system, even with the AFN and a running 3 kW auxiliary heater, struggles to maintain the temperature.

Best regards.
Christian.

That's why the 5 KW exists.

Quote:

As I was driving the car downhill, the temperature dropped from 70 to 65 degrees.

If the engine cools down while driving, as mentioned above, it indicates a thermostat that is no longer closing properly. The glow plugs should also be checked.

moby wrote:

As I was driving downhill, the temperature dropped from 70 to 65 degrees. The temperature difference was about minus 0.5 degrees. Recently, when it was plus 5 degrees, I noticed this while driving across the city and then back home, which was about 15km. However, the engine didn't even get properly warm, even though I wasn't driving defensively. What could be the cause?

If it happens for the first time under the same driving conditions and outside temperature -> thermostat.

If it has been the same way in past winters (I always have to get used to it!), then at least nothing has changed since then .
So, either the thermostat is always broken, or everything is okay.

And I drive an ASZ without glow plug heating... well, those do exist. I'd like to agree with Ulf here.

Hello, can the thermostat fail when you replace the water pump? Or does it not get touched during the process? I had the timing belt and water pump replaced three weeks ago.


cu moby

I highly doubt it, but dirt might have gotten in (or something might have come loose), right?

It's not impossible, but I think it's unlikely.

Just to add some context: I also drive an ASZ, and my commute is about 25 km. This includes both country roads and highways. Initially, I drive uphill on slight inclines, but after 3 km, it's mostly downhill. The last bit is through the city. With the current temperatures, I also don't see a middle position on the combined instrument panel, but that's been the case with my Golf since it was new. The T5 warms up and maintains the temperature when the auxiliary heater is running. If the auxiliary heater is turned off, the same effect occurs.

Quote:

Hello, as always, I drove the same route today that I have for years, a distance of 20 km. But today, the engine didn't even warm up until I got home. When I was driving downhill in the car, the temperature dropped from 70 to 65 degrees... But the engine didn't even get properly warm, even though I wasn't driving defensively.

I think that speaks for itself.

@moby

Start the engine and let it warm up until you feel a slight amount of warm air coming from the heater. Then, check if the radiator is also warm to the touch. In this state (or until the thermostat opens at approximately 85°C), it should still be ice cold. If it is already warm, the thermostat is definitely faulty. [/quote]