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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22903
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a 2004 Audi A4 convertible 1.8t. Was driving all fine

Customer Question

I have a 2004 Audi A4 convertible 1.8t.
Was driving all fine until yesterday. Then temperature shot up. I have had thermostat replaced. Water seems to be getting round engine as heaters are hot and all pipes I could feel have heat in them. Next step??? Temp sensor or water pump? Help
Submitted: 2 years ago.
Category: Car
Expert:  Matt replied 2 years ago.
I'd next do a reverse flush the cooling circuit (remove top hose to rad and use a hosepipe to push water into the engine until you get clear water out of the radiator hose) and top up with 30-50% fresh antifreeze. Also check that the small diameter bleed hoses that run from the top of the radiator and the top of the engine aren't blocked as this allow the air to vent back to the header tank automatically.If you still have a problem then check that the water pump impeller / turbine isn't spinning on its shaft. You should be able to achieve this by removing the bottom hose from the engine and use a screwdriver or similar to feel for the water pump impeller blades, whilst your assistant turns the engine over by hand.If you can stop the impeller with slight pressure from the screwdriver the pump needs replacing. Also its possible the belt is slipping so its worth replacing its especially if the rubber ribs are cracked or it looks shiny on flat side of the belt - while its off check that the tensioner and other pulleys all spin freely the exception to this is the AC pump ( if fitted) I'd also 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
Customer: replied 2 years ago.
Ok. I will admit there is little coolant in the system at present but didn't drive far at all and it wasn't a hot day and the temp had risen above normal. Put a hose pipe in the top rad hose and turn it on? And wait for the water to come from where? Have to excuse my stupidity. Thanks
Expert:  Matt replied 2 years ago.
hello you disconnect the top hose from the rad and then put the hose pipe into the hose to flow ater back into the engine until the water then runs out of the top of the rad where you've just disconnected the hose, run the hose for at least 1 minute
Customer: replied 2 years ago.
Ok. Bled system and had car running for 30 mins. Sat at 90, drove round a bit all ok. Went up bypass and car got hotter, slowed down to turn round and stopped and temperature dropped to 90. If I stay at low speeds all seems ok? Do you think I just need more coolant as not much in car or still think water pump?
Expert:  Matt replied 2 years ago.
hello 1st double check that the coolant level hasn't dropped if it hasn't then yes I'd move onto replacing the pump but 1st double check that the radiator isn't blocked in any way with debris before it
Expert:  Matt replied 2 years ago.
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