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Matt
Matt, Mechanical Engineer
Category: Audi
Satisfied Customers: 21724
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have an audi a4 1.9 2002 I changed the water pump/thermostat

Customer Question

I have an audi a4 1.9 2002 I changed the water pump/thermostat but heater is still blowing cold air and overheating I also had my head gas kit checked and system flushed and the radiator bottom hose is cold/could it be my heater metric or could I still have an air lock in my cooling system or the radiator is no good. could you help me please?
Submitted: 2 years ago.
Category: Audi
Expert:  Matt replied 2 years ago.
Hello

I'd suggest ensuring that you've got all the air out of the system as this sort of episode can leave pockets of air trapped and prevent the coolant from circulating properly.

So check that the small hoses that run from the top of the engine and radiator that run back to the header / expansion tank are free flowing and not blocked

If these are OK then remove the tank pressure cap and run the engine from cold with the heater set to full hot

As the engine starts to warm, squeeze the large hoses running to the radiator to help displace any air - all the time keeping an eye on the level in the header tank, making sure it doesn't drop below the minimum and open any bleed screws built into the top cooling hoses - closing them off as soon as they start to gush water

Once the engine is up to temperature the tank should be quite full. Switch the engine off and leave it to cool

Then top up to the mark once its all cold and replace the cap