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Coolant problem

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Malfuss, Mar 8, 2013.

  1. Malfuss
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    Malfuss Member

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    [Mar 8, 2013]
    Over the last couple of days my minimum fluid light keeps coming on, so I pull over, check the levels and if anything have too much fluid in the expansion tank as it's above the Max mark. Once I open the expansion tank, which lets off a bit of pressure, and get back in the car the light goes out and stays out until the next time it decides to come on.

    I'm thinking I might have an air lock or something? Any ideas?
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  3. Andie0
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    Andie0 Member

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    [Mar 8, 2013]

    Look into this as it could be blown head gasket as the excess gases and air may be escaping the cylinder thus pushing the coolant out of your system and into your reservouir
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  4. Malfuss
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    Malfuss Member

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    [Mar 8, 2013]
    Hmm, could this also cause an occasional drop in power? Nothing that lasts for more than a split second. Sorry, I don't really know how to describe it, like a flat spot I guess but a very very short one
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  5. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep VCDS Map User

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    [Mar 8, 2013]
    it could also be the water pump
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  6. Malfuss
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    Malfuss Member

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    [Mar 8, 2013]
    In theory the water pump should be fine as it was changed about 3 months before I bought the car and I have the receipts from when it was done. Guess I'm going to have to nip up the garage in the morning.
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  7. Andie0
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    [Mar 8, 2013]
    If just changed should be fine but could be faulty part! Check for milky substance under filler cap, also white smoke from exhaust!

    open the coolant lid when engine cold and start it, rev the engine and if the coolant bubbles or comes out then youve got a blown gasket!
    Rough running is a sympton but will get worse with time! I wouldnt driventhe car if it is head gasket as in some cases can end up cracking block! Is it overheating at all?
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  8. Malfuss
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    Malfuss Member

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    [Mar 8, 2013]
    Well, normally it never gets above 70 degrees. However, I had a good clear run down the motorway the other day and the temperature did rise a couple of degrees until I backed off.

    The hesitating only happens when the car is cold, once it's warmed up I never notice it.

    I'll have a look tomorrow morning when it's light.

    Do you think it would be safe for me to drive about 10 miles to the garage to get it pressure tested?
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  9. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep VCDS Map User

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    [Mar 8, 2013]
    could be the stat it should go to 90 and sit
    also could be the sensor in the bottle very common
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  10. Andie0
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    Andie0 Member

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    [Mar 8, 2013]
    Yer you will have to mate, you got to get it pressure tested just to be safe then you can eliminate that and start on other smaller things! Hope it goes well let us no tommorow what they say?! For the sake of a cheap pressure test its worth it and then like bez sais start eliminating smaller issues like sensors! But if the level is rising then i dont think that would be the bottle sensor! Theres a force actually making that coolant rise! But you should be reading 90 on gauge
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  11. B5NUT
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    B5NUT Well-Known Member VCDS Map User

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    [Mar 8, 2013]
    You should have some pressure in the coolant system as the coolant heats up. if your gauge is not reading 90 then I would look to replace the sat, but first get the car scanned with vcds, as it could be a faulty temp sensor. With the coolant warning light it could also be a faulty sensor.
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  12. Andie0
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    Andie0 Member

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    [Mar 8, 2013]
    Presure is supposed to be there thats a fact but in no way should the level of water rise in the tank unless its overheating or gases are escaping!
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  13. stu_m
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    stu_m Active Member VCDS Map User

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    [Mar 8, 2013]
    the water level will rise slightly as the water heats up because it expands!! thats why you get the pressure!! hence why its called an expansion tank!!
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  14. Andie0
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    Andie0 Member

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    [Mar 8, 2013]
    Fair enough, but a significant rise in coolant level in my experience has led to blown head gasket! Tracked my car on lydden last saturday and smashed the life out of it and coolant was exactly same level as when i started her! Also this happened on my starlet, which did start due to a stat being dodgyy but then led to gasket failure! Only talking from my own experience and dont want to see others make my mistake if i can help it! But telling this guy to get a pressure test as he is getting signs of failure is a pretty normal route to take! Eliminate the serious to help ease the worrying!
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  15. stu_m
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    stu_m Active Member VCDS Map User

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    [Mar 8, 2013]
    Yes I agree if your worried to get it checked I'm merely pointing out that the coolant does rise when it gets hot some rise a little to the point where you would think it hasn't moved some rise a little more

    Its knowing what is normal and what isn't

    I do fail to see how this would turn the level sensor on though as the sensor is at the bottom and if it did rise then the sensor would always be covered in coolant! if it was exhaust gasses been pushed in to the expansion tank they would rise through the coolant to the top but stranger things have happened

    It could just be a dodgy sensor when it gets hot
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  16. Andie0
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    [Mar 8, 2013]
    Agreed
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  17. Andie0
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    [Mar 9, 2013]
    Did you get your pressure test?
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  18. B5NUT
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    B5NUT Well-Known Member VCDS Map User

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    [Mar 9, 2013]
    Level sensors in the expansion tank do fail, had this on a friends skoda last month easy to replace.
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  19. Malfuss
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    Malfuss Member

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    [Mar 11, 2013]
    Right, took it to the garage and they don't think it's the head gasket, I'm not sure exactly what they did as I was too busy chatting! I have now ordered a new thermostat, new coolant temp switch and a new sensor for the expansion tank. I'll get those sorted first and see whether that fixes it. In the meantime, I'm enjoying driving my T4!!
    Last edited: Mar 11, 2013
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  20. Malfuss
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    Malfuss Member

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    [Mar 18, 2013]
    Just to keep this updated in case anyone else has the same problem. The thermostat and coolant temp switch has been changed. Car drives better and I thought it had sorted out the min coolant problem, however today it came back on. We didn't change the expansion tank sensor which I'm a bit annoyed about as I asked them to order me one. I still have slight hesitation in 5th when warming up but overall there is an improvement.
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