Audi A6 C4 2.5tdi after thermostat replacement strange noise

[Joop]

Hello fellows,

i have the following issue:
a few weeks ago began:the temperature warning sign was flashing,but the gauge shows only 53 Celsius at the instruments cluster,also in the hidden climate control menu.I checked the cooling level,replaced,and cleaned but nothing has changed.

I checked the temperature sensor.I made a few test with multimeter in cold and warm water.It seemed its working because of changing the value of resistance is cold and warm water.Also i checked the voltage level by the connector its shows the voltage level.So its seems temperature sensor is working correctly but allways shows the same value 53C.

After i replaced the thermostat,load back the coolant .I tried to make the air go out by running the motor without the coolant cap.

But now i have strange noise.I am not sure what it is,the timing belt or the water pump or something else,its similar as a truck noise.

I don't know how to check if the water pump is works correctly.

All tubes are not hard when i pushing

[Joop]

thank you for your help

[piotr]

i think it could help if you post sound clip of that noise.Is the air coming from the air vents nice and hot or just worm-isch?

[Joop]

i think it could help if you post sound clip of that noise.Is the air coming from the air vents nice and hot or just worm-isch?

Sorry i haven't found other sound upload service:
http://vocaroo.com/i/s0SOKhbv1KtV
Its began after replacing the thermostat.

First i thought there is not enough water in the expansion tank,but after running the motor for a bit it seems it is full with coolant water.

The warning signs could be shows the temperature or level fault.
The temperature must be okey,since the motor was just started,the level seems okey in the expansion tank.

Is that possible that the fault is with the thermo switch?
I checked the thermos switch connector with a multimeter its shows voltage level,so the cables seems okey.

Furthermore i can not see any bubble in the coolant expansion tank.

[AndyP]

That sounds like something mechanical rather than anything to do with water level. Have you checked all the belts and pulleys at the front of the engine?

[Joop]

That sounds like something mechanical rather than anything to do with water level. Have you checked all the belts and pulleys at the front of the engine?

I can check the loosing but not furthermore,
i thought the engine is not get enough water