cooling problem or air lock b6 1.9tdi

[R1carl46]

hi all i wonder if someone could help me in this long stressfull time of cooling problems,basiclly ive got no heat coming through vents,losing abit of coolant,engine never overheats,top hose is hot bottom is cold,changed thermostat 5 times and doesnt make any differance at all,ive tried bleeding it from the heater matrix but to no avail although when i pulled the pipe this morn there was no water coming out at all plus none returning to the expansion tank,the top hose isnt rock hard when hot and no usual signs of headgasket so i dont think its that,im wondering weather the rad is blocked,another faulty thermostat or water pump has packed up,ive looked for leaks and everything plus after a 50 mile drive the water in the expansion tank was only very slighty warm and there was no pressure at all when releasing the cap,this really is driving me up the wall any help will be very much appreciated thanks

[mikeybutch]

Are you using genuine stats? Others are often bad.What temp does it show?If you cant bleed the matrix it could well be blocked.Try flushing it with a hose

[R1carl46]

Hi mate thanks for the reply,the stats are from euro car parts so not genuine,I've flushed and back flushed the matrix till it runs clear and still no joy,temp goes upto 90 as it should and sits there never goes above or overheats

[mikeybutch]

ECP stat was the one that was bad but if it gets to 90 quickly yours seems OK.I have heard that its the small bores in the matrix that can block and flushing is then no good.

[Doctle Odd]

Check the water pump impeller

[Col]

Check the water pump impeller

If you take the thermosat out you can stick your finger in and feel if the impeller is freewheeling or in bits.

[mikeybutch]

But it doesn't overheat so pump is OK

[rowdy-999]

But it doesn't overheat so pump is OK

If the bottom hose is always cold ( even after a long run ) it must be over heating because there is no flow through the rad.

[Doctle Odd]

But it doesn't overheat so pump is OK

Take Col's advice, remove the thermostat amd put your finger inside towards the impeller. I think the impeller is wonky or in many pieces through the cooling system. This is quite common with plastic pump impellers

[pauldazzle]

+1 for water pump.
You should have flow from the headertank return pipe if the water pump is working, & the lack of pressure would also indicate pump failure.
In the winter the bottom hose not getting hot is normal in my experience with VAG PD 130 engines. Both my Bora TDi's were like that & my A4 has been the same for the past 4 winters & 60k.