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Help!! Over heating problems on 8L 1.8T.

Discussion in 'A3/S3 Forum (8L Chassis)' started by flatshifter, Apr 14, 2010.

  1. flatshifter

    flatshifter Member

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    Hi guys,

    Need your opinion and suggestion on this.

    Here's the deal and I'll try to make it as detailed as possible.

    Bro in law drives an A3 1.8T 2001 model(AUM engine) and on the way to work, the coolant temperature sensor's flange(only found out at a later stage) decided to crack and the engine over heated.

    He filled it up with some liquid based(copper me thinks) stop leak and coolant and returned home. Somehow the leak stopped but a day later it was revealed that the said flange had a hairline crack.

    Got a new replacement, replaced it and went for a test run.

    When the engine's warmed up, I let the in law drives it, with me inside the car and the temperature suddenly went up, even when there's air going through it(at speed).

    There's no external leak whatsoever found/noted. I noticed the fan not running into the 2nd speed(cut in at 97c)..since the fan is running after all, I was thinking the thermoswitch at the radiator's end tank at fault.

    Again, got a thermoswitch as well as the thermostat new replacement part which my bro in law says doesnt mind replacing it just in case, after all the engine is about 9 years old now.

    Before replacing them, I reverse flushed the radiator to remove at the sh*t*(if any) inside. I even reverse flushed the engine.

    Ok, after fitting the new parts, filled with coolant(green stuff), went for a test run.

    To my horror, the temperature still goes up! [​IMG]

    So i consulted a friend who works on european cars and told to check the cooling fan's speed if they're fully functioning..he also mentioned something about a relay board/fan control unit located somewhere on the passenger side's chassis rail that have failed.

    Reached home and tested the fan on both speed and it was ok.

    I consulted local audi forum members(ozaudi) and a member pointed to me check on the water pump. Engine warmed up, squeeze the upper hose and feel if it swells. It did. For now, I would assume the water pump is ok.

    As the fan is not kicking in into the 2nd speed, I would think the fan controller unit was faulty.

    Again, bought a new replacement controller unit and waited for it to kick in.

    Now, the fan stopped working completely! Im all buggered trying to figure out why as I was not rough with the wiring loom to the fan controller unit.

    Im gonna trace some wires/connectors now just in case. Waiting for you guy's opinion and suggestions on this.









    Danny.

    edit: it it got me thinking, if the car is at speed, there's air going through it, there's no need for the 2nd speed to cut in.

    Furthermore, maybe I did was pretty crude, I sprayed water(shower) in front of the car's grille to get some water to get rid of some heat from the radiator. As a heat exchanger it should work but it didnt.

    So what do you guys think? I havent pressure tested the cooling system but so far the car idles well, no steam/white "smoke" coming out..
     
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  3. golf

    golf ***** rent boy
    VCDS Map User

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    What's the mileage on it?

    I'd bet a lot of money on it being the water pump. Nearly all overheating problems on these 1.8T's are because of the water pump impellers breaking off and being unable to circulate the water properly.
     
  4. Essflee

    Essflee Well-Known Member

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    I'd definately change the water pump mate, very common problem...
     
  5. Welly

    Welly VX220 SC Driver :)

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    Water pump.....
     
  6. DaveA3

    DaveA3 Audi A-Trizzle!

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    thermostat is worth a shot aswell before the waterpump tho
     
  7. Welly

    Welly VX220 SC Driver :)

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    Not normally a cause of over heating.... but true.

    Thermos generally fail in the way that they open too early, or stay open, meaning that water gets too cool.

    Water pump is most likely for over-heating.
     
  8. DaveA3

    DaveA3 Audi A-Trizzle!

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    i had my old car (1.8TQ) thermostat get stuck on the small circuit which on journeys longer than 10 mins would shoot up to 110c

    on this car(1.8T) it was the opposite and took ages to warm up
     
  9. flatshifter

    flatshifter Member

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    Thank you all for the reply.

    Thermostat was replaced with a new one.

    It very likely the water pump. Just ordered stuff from ECS.

    Upon reading some threads on vwvortex, followed their "test", warm up the engine, bottom radiator should be warm as the top...mine doesnt...so water pump it is,...or a blocked radiator which is quite unlikely.


    Will update you guys soon'ish.


    Cheers mates!
     
  10. sportquattro

    sportquattro Active Member

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    If you are replacing the water pump then make sure you replace the cam belt, tensioner pullys etc at the same time, It's a big job doing the water pump and daft not to do the cam belt at same time, in the sameway if you are ever replacing the cam belt its daft not to do the water pump as well. As in deed you have found out.
     

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