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Coolant issue

cjm999 Aug 6, 2018

  1. cjm999

    cjm999 2017 RS3, Ara Blue Sportback

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    Hi guys, just wanting a bit of advice on an issue I have recently with my 67 plate RS3. Just over a week ago I got a low coolant warning on the dash, and upon checking the reservoir the level was way below the minimum by about 1.5 inches. I was over an hour from home and didn't have access to any proper coolant so a friend said I could just top up with water, which is what I did. Unfortunately I put too much in and it went over the top limit, but still I drove it home (slowly and in comfort) with no issues.

    I kept an eye on the coolant level for the next week and it did drop down to the proper level (remember that I overfilled it, not knowing that this may cause an issue at the time!) I decided to buy a syphon and proper VW/Audi coolant mix and emptied the reservoir and topped up to the correct level.

    All seemed fine, no overheating etc. On Saturday night whilst working at a wedding, I took a mate out for a quick spin for 10 minutes. I did hit the red-line at one point when missing a gear in manual and was driving it hard. I parked up for about 20 minutes before I needed to head home. When I started the car up I got a low coolant warning so immediately parked up and checked under the bonnet. There was NO coolant in the reservoir, and a fair bit of it appeared to have spurted out of the filler cap and across the engine bay. I had no idea what to do, so called up Audi Assist, who sent the AA out within just under an hour. The AA chap unscrewed the coolant cap, and low and behold the coolant appeared back into the tank and almost to the correct level. He then got some water and topped it up a little. Did a few checks with holding the revs up to bring it up to temperature and everything seemed to be running fine, and off I went home with no issues (again, very gently driven).

    I'm booked in at a garage next week for lowering springs fitted so they will also check the coolant at the same time. Just wondered if anyone had an idea what might be the issue here? I've had stage 1 APR remap done, if that might be linked at all?
     
    penetrator likes this.
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  3. PanamaS3

    PanamaS3 Well-Known Member Team Glacier Audi S3 Black Edition S3 Saloon DSG

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    either a leak somewhere or air in system which needs bleeding out is my prognosis (I'd say latter) having had similar issues...as have many others on here on multiple platforms. flush system.....pressurize overnight and check for leaks....none found then refill with proper mixture....drive once to temp....let it cool....check and top up....should be good to go after that (unless its a leak somewhere in which case need to find it and repair)
     
  4. penetrator

    penetrator Well-Known Member

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    Hi mate,

    I had my car in to Audi for a coolant issue a few months ago so it was 3 months old at the time, my car had also lost coolant and they checked the system and it was just an air-lock.
    I do check it very regularly now, especially being stage1.
     
  5. T-800

    T-800 Well-Known Member Team Glacier TFSI Owners Group VCDS Map User Audi RS3 quattro Sportback S tronic MQB Platform

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    I had this on my PFL once, it had dropped enough to warrant a warning light, more than likely when it was filled at the factory there was still some air in the system and over time that air has been pushed out of the system, hence the drop in the reservoir.

    Don't forget this is a sealed system the coolant is under pressure but cannot be compressed, however any air in the system will expand when things get hot and this is what you see when unscrewing the reservoir cap, pressurised air escaping and the coolant coming 'back' up into the reservoir.

    I always check it visually once a week when I'm checking the oil, takes seconds, but at least you know it's where it should be.
     
    penetrator likes this.
  6. Behind The Bins

    Behind The Bins Active Member

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    Off to check my coolant
     
  7. cjm999

    cjm999 2017 RS3, Ara Blue Sportback

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    Thanks for your replies guys. Any thoughts on how and why it escaped through the reservoir cap though? It wasn't much but enough to make a mess in the engine bay.
     
  8. D0C

    D0C Well-Known Member Team Nardo Team Panther Audi RS3 TTRS

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    Just massive heat and pressure.

    I remember my brothers classic Maestro Turbo which runs some serious power. He did a full bore launch and 50 metres down the road there was a bang with the screen covered in water...It was the coolant cap which had blew off!
     
  9. cjm999

    cjm999 2017 RS3, Ara Blue Sportback

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    To be fair I probably didn't let the car warm up enough before flooring it, plus hitting the rev limiter wouldn't have helped!
     
  10. T-800

    T-800 Well-Known Member Team Glacier TFSI Owners Group VCDS Map User Audi RS3 quattro Sportback S tronic MQB Platform

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    If you look at the coolant reservoir design you’ll see it has an overflow on the side
    [​IMG]
     
  11. cjm999

    cjm999 2017 RS3, Ara Blue Sportback

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    After a day of driving today, it seems that the level drops considerably when driven hard, but comes back up when the cap is opened. Is this normal?
     

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