How quickly does a water heater warm up?

Hi.

I've only just finished my second winter with my 1Z, and it's already surprising me again.

I just drove 30 km in temperatures ranging from -12 to -8 degrees Celsius: 10 km on a country road, 10 km on the highway, then country road and city. After that, the temperature gauge only reached 70 degrees (and that's not even a true 70, because of the gauge's plateau function).

My drifting practice on the university parking lot initially increased the speed somewhat, so that by the end, it even reached 90 km/h.

At an outside temperature of 6 degrees Celsius, I consistently measured a water temperature of 81 degrees Celsius on the highway (over a distance of 150 km), as measured with VAGCOM.

Now, I'm not going to take my laptop to the garage anymore .

My question:
Is it normal for the car not to warm up when driving moderately, or does this indicate a faulty thermostat?

Okay, here's the translation:

Thank you.
m;

Hello,
I'm always surprised by the long warm-up time of my 1Z. I'm used to Lancia Deltas. But what you described seems perfectly normal. I experienced similar temperatures (minus 12°C) during the holidays, and it took my car about 25 minutes and 8 km of highway, followed by another 8 km of stop-and-go traffic, to reach the 80° mark on the temperature gauge. However, I only turn on the heater when the gauge reaches 75°, and then only on the first fan setting.
I also cut a plastic sheet to fit over the radiator (630mm x 320mm), but my motivation isn't high enough to actually install it given these temperatures. It would involve unclipping the grill and removing a support bracket...
The temperature at the upper radiator hose isn't always a reliable indicator of a stuck thermostat, as some heat transfer usually occurs through the stagnant water. Also, it's difficult to touch the upper part of the radiator because it's quite obstructed.
Okay, I think everything is within the normal range. In fact, if the fuel consumption settles around 5-5.5 liters with moderate driving.

Best regards from Klosterneuburg, where the current temperature is -4°C.

robert

Thank you for the tips.

"However, I'm currently consuming more like 6-6.2 liters. This is probably due to the high-speed driving on the highway. With every fill-up, I've been doing at least one of those 100km stretches at full speed (because I wanted to get to my family quickly) - and even a 1Z (including the wagon version) consumes a lot of fuel at 170-180 km/h."

If the thermostat is working correctly and allowing coolant to flow, then blocking the radiator won't achieve anything... or what are you planning to do with that plate?

m;

I think he's trying to see if the thermostat is still working properly. I've tried something similar with a piece of cardboard before. However, the test isn't very good because the radiator still releases a lot of heat, even if it's not directly cooled by the airflow (similar to a radiator).
By the way: I had a new thermostat installed last fall, but even when the water temperature indicator shows 90°C, the temperature drops to around 80°C when I'm driving on the highway with the heater on (even level 2 is enough to cause that). Also, my Passat doesn't have the 'modified' water temperature indicator yet.

Hi.
'On my 1Z (Audi 80 Avant, manufactured in 1/93), it also takes quite a long time (about 12 minutes on mixed roads at -4°C) to reach operating temperature. I initially suspected a faulty (open) thermostat and, at an outside temperature of 0°C (brrr), I replaced it (unfortunately, my garage isn't heated). The conclusion: the old thermostat was probably still working. However, mine maintains the temperature even at extremely moderate speeds (120 km/h), even with the heater on (fan speed 1). My previous car (a Golf TDI 1Z, manufactured in 10/94) warmed up faster; it already had auxiliary glow plugs in the cooling circuit near the cylinder head.'
My radiator grille has an original plastic cover on the inside, which reduces the airflow through the radiator and, consequently, into the engine compartment.

Regards,
Hermann.

Evening.

If the thermostat is actually working correctly and allowing coolant to flow, then blocking the radiator won't achieve anything... or what are you planning to do with that plate?

Simply less airflow in the engine compartment. I'm actually thinking of something like a radiator shutter or a blind, like you see on old trucks. That would be a real feature in these temperatures!
The flaps behind the radiator also open at a certain speed.
Oh yeah, I also installed the auxiliary glow plugs.
When snow accumulates on the radiator again, blocking the airflow, it's easy to conduct comparative tests on familiar routes. In my case, on about one-third of the route, the temperature is the same!

Best regards, Robert.

I noticed this after reading the thread.
Yesterday, after about 3 km, I drove out of the town onto an open country road and then traveled another 6 km, with a small village in between. After that, the water temperature, according to the gauge, was almost 90°C, and the car was nicely warm. This morning, things didn't progress as quickly due to the snow. The result was a maximum speed of 55 km/h, even on the country road. Even after 20 km, the car wasn't warm (only lukewarm), and the water temperature had only reached around 70°C.
That means the diesel engine doesn't warm up at all at low RPMs. I was driving at 45-55 km/h in fourth gear because the traction wasn't very good otherwise.

I have something else to offer, I'm currently on my way home from work. It's 60km and the outside temperature is -15°C.
The engine only briefly exceeded the 80°C temperature threshold once, but quickly went back down. Otherwise, the maximum water temperature was 70°C.
It was correspondingly cold in the car. On the country road, I drove at approximately 80 km/h, no more. In the towns, the water temperature would reach around 70°C or a maximum of slightly above that, but on the open country road, it immediately dropped below 70°C.
It's only been like this since today, because it's so incredibly cold now. But it shouldn't be possible to freeze in a car, should it?

edit: Not that I'm supposed to be changing the thermostat in this freezing cold weather...

I've already tried that before, as I've had similar experiences with my AHF. The conclusion is that the problem wasn't the thermostat. At these arctic temperatures, our TDIs simply don't warm up quickly. Even after replacing it, my engine didn't warm up any faster.
Just calculate it.
Für Tempo 100 brauchst Du maximal 10 KW Motorleistung. Bei einem angenommenen Wirkungsgrad von 30% bleiben 7 KW Wärmeverlust übrig. Damit müssen eine viertel Badewanne voll Kühlwasser aufgeheizt werden, der gesamte Motorblock schreit nach Wärme, das Getriebe leitet auch noch einiges an Wärme ab. Dazu kommt die Durchlüftung des Motorraumes und die Innenkühlung durch die eiskalte Ansaugluft. Da bleibt einfach nicht viel für den Innenraum übrig. 7 KW würden zwar zum Heizen reichen, die kommen aber bei so geringer Motorlast nicht im Innenraum an. vor allem dann nicht, wenn man nur 50 fährt. Allein der Wärmebedarf zur Innenraumbeheizung ist enorm, da es einen ständigen Luftaustausch gibt. Versuche mal, einen Wohnraum mit einem 2 KW Heizlüfter bei offenem Fenter aufzuheizen. Das It's not possible.
Unfortunately, I don't know the exact values, but I think the heat exchanger already provides a substantial 7 kW of heating power, which should be enough to cool the engine through the heating system alone, even under moderate load conditions.

Under those conditions, a gasoline engine simply has a dramatically lower efficiency and burns significantly more fuel. This also causes it to warm up faster.

Best regards,
Uwe.

Hi,

That also seems to be highly dependent on the specific engine and car.

"I managed to increase the average speed (ASV) of my car, which I was driving in city traffic for 10 km, from an oil temperature of -11.7 degrees Celsius to 64 degrees Celsius. There was still a tendency for further increase. The engine speeds were below 1500 RPM, with minimal acceleration, and a maximum speed of 60 km/h. During this process, the water temperature remained unchanged."

Yesterday morning, the temperature ranged from -2 degrees to 75 degrees - also, there was oil again.

"The other day evening, while driving on the city highway (80...100 km/h) at -4 degrees Celsius, the temperature was constantly rising. After about 20 kilometers, it had reached 94 degrees Celsius (which is the oil temperature - the fake water temperature doesn't really tell you much), while I had seen 80 degrees much earlier."

In a previous thread on this topic, someone also suggested that the lower engine cover might play a significant role, because, for example, the ASV engine in the Ibiza is almost completely enclosed from below. I suspect that this wasn't the case with the 1Z.

Furthermore, the Passat might have a larger engine compartment, as there is hardly any space left around the engine in the Ibi, which also hinders heat dissipation.

Best regards,

Jan.

Hi,
As mentioned elsewhere, the heat loss in a TDI engine is primarily and significantly greater than in a gasoline engine, and this heat is lost through the exhaust and is therefore not available for heating.
Therefore, we also have electric auxiliary heaters and cast-iron standing heaters.
The first TDI 89 engine in the Audi 100 already had a lower engine compartment cover, and presumably all 1Z engines did as well. A slightly newer feature is the engine bay encapsulation, i.e., the plastic cover over the cylinder head.
The heat loss during operation through the engine compartment is likely to be low: A few weeks ago, there was an article in the VDI Nachrichten (a German engineering publication) about this. To reduce cooling when the engine is idling, they are experimenting with a complete insulation of the engine using 2-3 cm thick PU foam. Only the connections, especially the exhaust manifold, remain exposed.
It wouldn't have any effect on the cooling system in the facility!

Okay, so my 1Z model has the lower "diaper" only, and only the oil pan is exposed. The AFN engine also has something related to this (there's a part for it, at least).

I installed the AFN cover above, but I removed the hood insulation because it was sagging and scratching the AFN cover.

It's brand new and will be back on soon.

m;

Hi,
As mentioned elsewhere, the heat loss in a TDI engine is primarily and significantly greater than in a gasoline engine, and this heat is lost through the exhaust and is therefore not available for heating.


Hmm, won't the charger (partially) be powered by it?

By the way, my Passat still doesn't have the 'modified' water temperature gauge installed.

Since when has it been installed?

Best regards, WarLord.

Hi,

Quote:

Only the oil pan is hanging out.

It's well-insulated at the ASV, but I can imagine that quite a bit of oil heating is lost in the winter.

Best regards,

Jan, who experienced the first snowfall of the year in Berlin today.

WarLord wrote:

Hmm, won't the charger (partially) be powered by it?

Basically, yes. Most complaints arise when the turbocharger doesn't build much pressure under partial load. Under high load, some exhaust gases bypass the turbocharger through the wastegate, or the variable geometry vanes (VTG) are set to "full boost." Furthermore, only a portion of the energy extracted from the exhaust gases by the turbocharger is returned to the engine; some of it is dissipated through the intercooler.

@ Jan

Could you please take a picture of how it's packaged?

Just a flat surface, or as I described it?

m;