[wodorof]

Hi,
I have a question about electric coolant pump, in a6 c6 2.7 tdi.
There are no dtc’s in hvac or engine, pump switches on for 3-5 seconds
then goes off for about minute, and cycle repeats.
Is this normal behavior?

Thanks in advance !

[Dana]

Do you mean the one at the front right of the engine?

[wodorof]

i meant this small one with two valves on top, it`s located on the right side between engine bay and cabin, it is connected to heater core

[Dana]

This is purely for the heating and it is actually controlled according to demand.
Do you have problems with the interior temperature?
Is the temperature set the same on the left and right but the temperature is different on the left and right?

[wodorof]

basically it is always cold inside the car,
flap motors seems to be working, it doesn`t matter how i set temperature,
hoses and heater core are also cold, like there is no coolant circulation,
many things were checked, and amount of noise which this pump makes (it can be heard from inside of the car) combined with weird 'duty cycle', makes me suspicious..

[Dana]

There are also two valves that are supposed to control the whole thing.
You shouldn't hear this in the interior.
Has anything been repaired on the water circuit?
Because this engine must be vented with a vacuum!
Not that there's air in it.

Can this be ruled out? Check the part with Odis if possible.

This part has caused problems before. There is even a technical product information from Audi.

I'll see if I can find it.

[wodorof]

Because this engine must be vented with a vacuum!
Not that there's air in it.

what do you mean exactly ?

[Dana]

The cooling circuit of the 2.7-3.0 TDI must be vented with a vacuum, otherwise air remains in the circuit. Which is very bad!
Was the cooling circuit open for repair?

[audi666]

This is not true.
I work a lot with 2.7 & 3.0 TDI V6 and it is not mandatory to use a vaccum to bleed the cooling system.

Refill system, turn on engine, wait to arrive at 90 degrees and set the blower at max speed and max heat (with AC off).
This will allow antifreeze to circle in the whole system.
Do this with antifreeze cap off and fill it as it drops level.

[Dana]

Since the 2.7 and 3.0 TDI engines often have an auxiliary heater or a parking heater attached to them, it is highly advisable to bleed them with a vacuum. For most VAG engines, there is even a test programme in the ODIS which is also very advisable as the valves are also controlled.

I wouldn't want to rule out the possibility of doing it without, but most people do it wrong and that's where the next problems arise!
Don't always assume for yourself, as not only professionals are reading along here!