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bottom hose

Jules May 9, 2007

  1. Jules

    Jules Member

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    Hi I have an A4 TDI B5 chassis, i can't get the bottom hose warm? please can someone tell me how or what to look for. I have just put a 38,000 mile engine in, I have refilled the coolant twice now took the brand new thermostat out and tested all ok there was water both sides of the thermostat, filled it up like it says in the haynes book engine runs sweet needle stays at 90 top hose nice and warm rad still cold. The viscous fan is always spinning should it? also do you think it maybe the water pump? please help driving me mad now.
     
  2. johnie72

    johnie72 Member

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    definately sounds like the water pump to me if only the bottom hose stays cold. Is there alot of pressure in the cooling system, are the hoses very hard when hot?
     
  3. Jules

    Jules Member

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    The top hose is hard also a hiss when I take off the cap from the expansion tank, apparently it is a right b***h to bleed a TDI. So have left the cap off to see if any air will escape.
     
  4. bredhurststeve

    bredhurststeve Member

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    my B5 1.8T is in the garage at this moment as it started overheating at the weekend.
    my mechanic has changed the thermostat but the top hose gets very hot whilst the bottom hose stays coool, so it's a new water pump for me i think.
    the fan is a viscous type which spins all the time and if im correct the heater fan cuts in once the rad gets too hot.
     
  5. johnie72

    johnie72 Member

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    If only the top hose gets hot and there's plenty of pressure in the system it would point to the water pump. If there wasn't much pressure it could just be an airlock.

    I would get the water pump and thermostat done if the problem persists. You don't want to risk overheating and blowing your head gasket.
     
  6. bredhurststeve

    bredhurststeve Member

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    well it was the water pump which was totally knackered, impellor had broken vanes and was hardlymoving whilst the shaft spun.
    £250 later, all is well
     
  7. Jules

    Jules Member

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    Well I have just replaced the waterpump with the metal impellors form GSF still the same at the moment though.
     
  8. Jules

    Jules Member

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    All I have done to it recently is took the thermostat out and it runs ok but doesn't get very warm, only about 60" but all the pipes are warm and the rad is warm so I am going to get a new stat from audi do a test first then try again.
     

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