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Thread: Loosing Coolant Question

  1. 12th January 2010, 10:07 PM #1
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    The Fish
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    Loosing Coolant Question

    On a previous trip to Fraser just before Christmas the top radiator hose on my 300Tdi Disco split and was loosing coolant really quickly. I have a low coolant alarm and this sounded saving me from overheating the car. After a patch job on the hose I managed to drive home where I replaced the top hose.

    A few weeks later I replaced all of the remaining hoses for some piece of mind (just as well in the end as some of the others had internal cracks as well). Since replacing all hoses I have been loosing coolant at roughly 2L per 2-300km.

    I have given all hoses a thorough look over with no obvious leaks or weep spots. I also had the system pressure tested and gas tested today with the mechanic saying that both seemed fine. He also had a look over externally and couldn't find any leaks either.

    I'm fearing a blown head gasket but it seems coincidental that I start loosing coolant after changing the hoses. The car still runs great, starting fine and the temperature gauge not moving at all even in soft sand.

    Is there any other tests I can do to find where or why I am loosing so much coolant?
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  2. 12th January 2010, 10:29 PM #2
    PAT303
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    I don't know how you could loose 2-3 litres of coolant but still show up fine with the checks.Does it blow white smoke at cold start-up?. Pat
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  3. 12th January 2010, 10:32 PM #3
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    seano87
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    2L per 200-300km is quite a lot. Do you know if it's losing any if just left stationary, or is it only when being driven?

    Have a good look over all hoses, and particularly around the joins for white marks left from evaporated leaked coolant (assuming there is still anti-boil/freeze mixture in there, not just water). I believe you can get an exhaust gas analysis done which will show up water/coolant in the exhaust.

    How is the engine oil looking? Signs of a blown head gasket can include contamination of the engine oil - it will look grey and murky, and if more and more oil seems to be magically appearing higher up the dipstick...

    Did you refill the cooling system properly after changing the hoses? It is very easy to create an airlock and further problems if not done properly (I've possibly been there, done that, or it was a big coincidence as it was a couple of thousands k's later - no damage other than blown gasket thank goodness though).

    I'm sure others will chip in with useful advice and suggestions too, good luck with it all - something is definitely not right though!

    Seano
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  4. 14th January 2010, 07:02 AM #4
    IanP
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    This may seem obvious, but after you install new hoses you do need to go around and re-tighten after running the vehicle for a week or two when the hoses have 'softened'. A minor leak at a hose connection can easily account for a few liters each 2-300K.

    Ian
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  5. 14th January 2010, 08:54 AM #5
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    350RRC
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    This loss of coolant could be caused by having air in the system which will expand more than water when hot, expelling water out of the expansion tank when you are driving. Tends to compound itself if the radiator cap is faulty.

    There have been quite a few threads on getting all the air out of a TDI system. The other thing worth checking when you have all the air out is the radiator cap. Make sure the little valve that lets air back into the system as it cools is free to do so. If it is faulty air can be sucked into the system from a lot of different connections, even if they don't leak under pressure.

    Have had this prob with a 350 and it was a combination of both the above.

    cheers, DL
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  6. 14th January 2010, 10:28 AM #6
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    Disco44
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    This is what happened to me when I was touring in WA.I was losing coolant so had it pressure tested, nothing showed up.This went on for a few weeks.One day while parked on concrete, after a short drive,noticed coolant leaking got under could not find from where.Took it again to have a pressure test when I arrived no leak.To shorten this story the leak was eventually found to be from the water pump which is alloy.This may sound crazy but the mated surfaces ( pump to block) had corroded to a hole that was quite sizable when cold. As the motor heated the expansion was so much it closed the hole.That was why the coolant leaked after the short run mentioned.Put on new pump fixed.
    Because of the position of the pump it was hard to see just where the leak was and the expansion of the hot motor made all pressure testing seem ok.
    Hope this helps.
    John.
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