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  1. #1
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    Suspected head gasket failure.

    Me again folks. Ill have my own forum soon!!!

    A bit of history might help for anyone who hasn't read all about my woes!

    about 4 months ago the water pump failed. It was replaced and all was fine.
    a few weeks before xmas the temp sensor housing popped and was replaced.
    when it came back the temperature was taking ages to get up to 90. I was told the thermostat must be dicky and decided i could do the job myself to save a little bit of money.

    New thermostat working fine as far as opening and closing goes.

    Im satisfied that the system is bled fully. Water coming out of bleed screw on top pipe and from bleed hole on heater pipe.

    And heres the "but" :-

    As the temp gets to about 88deg the hose that goes to the top of the expansion tank starts to judder every few seconds and the coolant in the expansion tank starts to gurgle. If i rev the engine it gets worse and eventually, as the temp climbs to about 90, it overflows and spews out a load of coolant. Its like an air lock but i can't bleed anymore air out.

    If i leave it to tick over when it does finally get to about 93 the thermostat opens and cools it back down to about 90 but the juddering and gurgling is still present.

    I have checked the temp on the gauge and vagcom and also with one of those infrared laser jobbies on the top hose and all 3 match within 1 degree.

    The hose that goes to the top of the expansion tank gets very stiff while this is all going on so i suspect the pressure in the cooling system is getting high and forcing the coolant to overflow.

    Is there anything that could cause this other than a blown head gasket?


    Dan
    (feeling slightly sick)
    Last edited by casiodan; 4th January 2011 at 22:45.

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  3. #2
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    UPDATE.

    Ive just tried bleeding it yet again and im convinced its fine.

    However this time with the laser thermometer thingy i checked the temp of the metal pipe with the bleed screw on it that runs from the top hose and it is getting over hot. The bubbling starts just as that gets to 100deg but vag com and my temp gauge are only reading around 85 when this happens.

    Im now thinking water pump again
    Last edited by casiodan; 5th January 2011 at 09:51.

  4. #3
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    When it starts to gurgle, do you have the expansion cap fitted?

    Do you have proper G12 coolant in the engine?

    The cooling system shouldnt be boiling until around 120c if the cap is on and sealing. If its not on and sealing, the system cant pressurise and the water will boil at a much lower temperature.

    Are the heater hoses getting hot?

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    oops! that was the most stupid thing i ever have posted on here, and i have posted some silly stuff!

    I had the bloody cap off didn't i! It does have the g12 stuff in it though.

    Right, now ive left it idling and its got upto temperature with no gurgles, the fans have kicked in and out so i guess that indicates the new stat is working.

    The temp on the top pipe is at about 110deg? does that sound right?

    Im ****ting it about taking it for a run though, im convinced its gonna overpressure.

  6. #5
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    110c does sound high, that said though, the coolant temperature sensor sits in the plastic housing that FEEDS that metal pipe, i cant really see how the CTS can be registering 90, but the pipes at 110c unless your infrared thing is just being a bit oversensitive?

    Not sure if the B6's can do it, but on the B5 you can press Recirc and then Up arrow on the Climate unit, and then scroll to channel 49 using temp + and press recirc again, which then displays the actual coolant temperature on the climate display.

    You can then take the car for a drive and see exactly what the temperature is doing.

    If your climate unit wont do that, then if you have vagcom you can sit the laptop on the passenger seat in measuring blocks and go for a drive.

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  7. #6
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    i have vagcom, i don't think the climate trick works on mine. Where is the sensor for the vagcom reading?

  8. #7
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    Just a word of advice on the laser pointer /IR thermometers, they take a cone shaped reading, the closer you are, the more accurate. I have a fluke one to hand here and if I wanted to measure an inch pipe it I would have to have the device as close as an inch to the pipe. These devices take an average reading so if you are pointing it at the pipe and the engine block (which could be several degrees hotter) it would give you a high reading. Also if you are reading a blank space as well, (nothing behind the pipe capable of emitting IR) this will throw of your reading too. For the task you have you are much better off using a small bead probe taped to the pipe in question.

    As for your other problems i'm none the wiser, I am in a similar vessel too. My car takes 3-5miles to heat to 90 with no heater on ,even longer if it's on. But it is winter, I can't remember did it do the same last year. I'm thinking maybe my stat is stuck open. Anyone where it is on a 1.9 diesel ?
    Last edited by defsix; 5th January 2011 at 11:36. Reason: Grammer Nazi's
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  9. #8
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    The sensor for the dash/vagcom/ecu sits in the plastic housing on the back of the cylinder head that feeds the metal coolant rail.

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    Ok so that should be reading the same temp as that metal pipe that connects to the top hose, unless the water pump isnt working efficiently?

    There is water flowing through the heater pipes so i guess that can only come from the water pump?
    Last edited by casiodan; 5th January 2011 at 12:07.

  11. #10
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    yep, i suspect your IR thermometer is just a bit inaccurate.

    Get out and drive the thing!

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    eek, i guess thats the only thing for it, im petrified of it over heating and doing some serious damage. oh well ill never know if i dont try.

    If i keep a feel of the heaters and they stay warm that should be a pretty good sign that i haven't lost coolant shouldn't it?

  13. #12
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    The B5's have a coolant level sensor in the resovoir, and i'd be surprised if the B6 didnt also.

    If the coolant drops you'll get a nice warning on the dash.

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    yeah it does, thats the second stupid thing ive said in one thread!!!! Doing well. I blame the sick car for messing my head up!

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    Aragorn, are you saying that the water gets to the thermostat before it gets to the metal pipe?

    Also am i right in thinking that if a head gasket is causing overheating its not the heat from the engine but the excess pressure caused by gasses that causes the coolant to overflow and then overheat due to lack of coolant.

  16. #15
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    i may have mised you putting this in a post some where but just drive the car to a local and ask them to test to see if the head has gone it takes them les than 10 mins to do this and then your mind is at rest mate you can also tell when the car temp is at 90 if you put the heaters on high and set it to as hot as it will go if it blows its self cold good chance it is your head or just a blody good air lock also you would be losing warter and have to top it up most days after say a 30min drive i no this as one of my old cars did this . defsix i have a tdi 1.9 and in this cold weather it can take up to 20 mins of stop start driving or 5 plus miles so id not worry to much mate sounds fine to me and iv asked this ? a few times on here and at my local lol and diesels tend to run colder and also self cool to a point ;-)
    Last edited by simon.m; 5th January 2011 at 14:12.

  17. #16
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    His engine is fine, he jsut needs to go have a drive and put his mind at ease.

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  18. #17
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    sure it is but if it was me id be getting it tested as im a worry guts lol

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    'Worry Guts' .......... Im changing my user name lol.

    Ill take its steady on my run home and have a look, if its ok then ill give it a bit more of a blast.

  20. #19
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    lol

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    Did you bleed the system by taking the top left hose from the heater core inside the plenum (next to the battery) and reveal the bleed hole ? Keep a nice steady 1500 rpm's and when the stat opens then a nice stream of coolant should flow from there. Let it flow a few times then put it back and make shure you have plenty heat from the heater matrix...
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  22. #21
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    im getting a stream from there before the stat opens. The heater system does bypass the thermostat though.

    Yes plenty of heat
    Last edited by casiodan; 5th January 2011 at 15:35.
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  23. #22
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    well im home.

    It wasnt quite up to temp when i got in but i left it to idle for a bit until the bottom hose got warm so i knew the stat had opened. I took it round the block a couple of times, nowt aggresive though and it seems fine. The top hose is really hot which is concerning me a little bit but its probably me being paranoid now.
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  24. #23
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    ha see you wasted no time putting the worry guts up lol

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    yeeah, im still worried even though it seems ok lol
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  26. #25
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    The top hose will be at engine operating temp, and unless your super-human, 90c is going to feel hot!

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    yeah, the rubber hose is exactly what vagcom says. its the metal bit thats hotter still, surely that should only be as hot as the coolant in it! it wouldnt pick up heat from anywhere else would it?

    i guess one way to tell would be to get it up to say 80c on the metal and then stick a thermometer in the bleed screw hole and see what the coolant temp is?
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  28. #27
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    no, its not possible for the metal to be hotter, your IR thermometer is just wrong.

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  29. #28
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    I agree.

    Does the temp gauge and vagcom measure the water temp at the hottest point in the system, i guess that is nearly straight after the water has passed through the engine?

    And one more thing (in a columbo stylee), i can hear a 'ticking' sort of noise when i rev the engine that wasnt there before, it sounds like tappets i suppose but i can only hear it when i sit in the car i cant hear it with my head under the bonnet.....could this be the water pump?

    I suppose the only way of knowing if its the water pump is to take it out and inspect it?......no simple ways to check?

    Sorry guys, i know im dragging this out, but i promise im learning a bit whilst im dragging it out.
    Last edited by casiodan; 6th January 2011 at 09:54.
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    Well now im convinced,

    The coolant has gone milky already ive only driven it for about 5 miles.

    Thats the end of that!

    Better walk to the shop for a decent supply of cigs and beer to help me decide what to do.

    Its got 150k on the clock so i cant see any point in repairing it. I guess a new engine is the next best solution but even that seems like a lot of money for an 8 year old motor.

    Edit.

    Im clutching at straws now. how about the oil cooler?
    Last edited by casiodan; 6th January 2011 at 18:36.
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  31. #30
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    how much would it cost to have it done mate it maybe worth it if you want to keep the car

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    well i guess ill be looking at 300/400 just to get the head off and checked wouldnt i? Assuming the head itself is ok then i guess im looking at 600 minimum for the head gasket changing. If the head is gone then a new engine will be cheaper?

    Never got to the shop for cigs and booze......its raining. typical
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  33. #32
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    not that this will help you mate but evan if it cost you 1500 it maybe worth it in the long run the cars going to be worth a min of 4000 to you any way fingers crosed its the cheaper job for you mate

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    cheers mate, ill let you know what the final outcome is, im gonna have to get it confirmed i suppose.
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  35. #34
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    yep that u will

  36. #35
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    booked in on tuesday. gulp!
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  37. #36
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    I went out this morning to check out that coolant again and in the daylight it didn't look too bad. I have just been on a bit of a blast. I went about 2 miles down a dual carriagway with roundabouts so plenty of stop starting, i then jumped on the motorway for about 2 miles and turned round and came back the same way. The temp never got above 88. no pipes blew off and when i checked the oil cap it was clean.

    The only negatives are the amount of steam from the exhaust and when i opened the bonnet im sure the top hose is way too hot. i just dont remember it being that hot from before.

    I could maybe explain the steam from the short runs but even when it was upto temp it still steams. I also replaced the dipstick tube today after noticing it had broken, that will obviously have caused condensation.

    Im still gonna get it checked over but im feeling a bit more positive today.
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  38. #37
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    well hope all is ok mate

 

 

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