no heat, almost

[dieselBB]

My 2001 Beetle (1.9L TDI) blows hardly any heat.
At outside temp ~45 F, the air coming out is barely noticeable warm after 3-4 miles of driving. Blue coolant light goes out after 1/2 mile.
Is this normal?

[Smileybug]

Is the airflow good, just not very warm?

[psaboic]

I have Jetta TDI (pretty much same car. For years now when it gets cold outside it takes a good 5-10 miles of driving to get solid heat. Reason why is that the TDI motor uses the heat it generates to aid combustion, unlike a gas motor where the heat is basically exhausted or used to heat the interior of the car.

As long as you get solid heat after 5-10 miles of driving you are fine. If you had a temperature gauge (Like my Jetta) instead of that damn light you would see on cold days the needle does not even move until about 7 miles of driving. Once when it was -10 outside, I drove nearly 15 miles before the air started to get warm.

Short and sweet, you have no issue, and welcome to the world of diesel in the winter

[dieselBB]

Thanks for the reply.It makes sense and was what I hoped for.
I am driving MB diesels for over 30 years and they blow warm air fairly quick.
The cooling system is somewhat different, though. They use a 2-way thermostat that circulates coolant through the enging bypassing the radiator up to a certain coolant temp.

[janitz]

When it gets really cold here, it won't really get warm until I drive almost 20 miles.

Then it goes from warm to OVEN.

So I start my drive to work with my coat done up, gloves on, hat on, and by the time I get to work I've removed hat and gloves and opened my coat, turned down the temp.

For the last five years I've been saying, "Man I really need to build a garage next summer."

And then come summer, I end up doing other things.

[AndyBees]

Unless the T-stat has been changed in the engine, your 2001 model is probably due a new one. The T-stat typically begins to default in the open position which results in never attaining normal operating temp on a cold day, even on the expressway at 70 mph.

The ALH engine's T-stat does not allow coolant to flow thru the Rad until the opening temp is reached. The coolant from the oil cooler (which is a warmer in winter) and the round tank all circulates to the back side of the T-stat into the Coolant Pump (water pump) housing......thus the sustained circulation of coolant during warm-up and on!

The coolant flow to the heater core is directly out of the head and EGR cooler on the back of the Intake. The EGR cooler actually aids in warming up the coolant too. Some engines were equipped with three GPs in the flange off the back of the head to increase warm-up in the cabin and of the engine indirectly (flow back from the cabin and extra load on the engine from the Alternator pumping out current to fuel the three GPs). .. . . .

I suggest that anyone with a TDI that doesn't have a temp gauge to get a ScanGauge (borrow one) to determine if the engine is getting up to temp!

Lastly, the TDI engine's extremely efficient design is why it warms-up slow.........no other magic! It only consumes about 1/3 liter of fuel per hour at idle......that's sipping mighty slow! So, not much fuel burned, means not much heat generated! Pretty simple! Right?

[dieselBB]

Thanks for your insight and wisdom.
Makes all the sense to me.
Why didn't I think of that (LOL)

[Lew]

One thing I might add, never go over 2800 rpm's until the engine is up to normal temps.....Coolant light goes out!