1.9 tdi thermostat problem, maybe?

Discussion in 'TDi - SEAT Diesel specific topics' started by FRich, Jan 4, 2011.

  1. FRich

    FRich Guest

    Hi guys (again)

    If anyone's been keeping track I'm having some trouble with the cooling system on my Ibiza. I had the water pump replaced as I was loosing coolant and it turned out that was the culprit.

    NOW for the new issue! When driving home today the heater was blowing out lovely tropical air but all of a sudden it turned Arctic. Checked the temp gauge and I was running at about 100 but slowly went back to 90. I had this for about 15 mins (10 miles) then I got my heater back and the temp settled. No coolant has been lost (quickly checked when I got home) but I could hear a slight hiss/bubble coming from the expansion tank.

    Could I have a faulty thermostat? :cry:
     
  2. MJ

    MJ Public transport abuser

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    there may have been an air lock within the coolant system, this is quite common on the vag apparent self bleeding system which only, in reality bleeds itself once you give the vehicle a good thrashing. Chances are its now released it and wont do it again.

    just keep an eye on it over the next few weeks to see how you go.
     
  3. FRich

    FRich Guest

    Well on a long trip (140 miles each way) I lost some coolant but the heater was fine. surely the air lock would have been resolved in that sort of distance?
     
  4. MJ

    MJ Public transport abuser

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    i would have thought so, its not uncommon for the header tank to spew a little coolant out when it dumps the air (it comes out as steam).
     
  5. FRich

    FRich Guest

    The header tank was wet on the top. I'm just worried that its taken this long to get rid of the air lock. but if its gone then I'm definitely happy! I'll keep a close eye on it for a while and make sure. what's the best way to check the thermostat if that it the problem?
     
  6. Seatmann

    Seatmann Rough around the edges

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    I've never had any issue with airlocks on my 2000 1.9tdi Cordy. I just fill it up to the mark, start the car and let it run for 30 seconds or so then top up to the mark again and all is dandy. I have heard of dodgy thermostats though, mainly on some of the vag tdi specific websites. They're always on about using oem or nothing. Take the lid off the coolant tank when cold, make sure the heater is turned up full then start the car. Gently raise the revs a bit just to help circulation. Do this for a few seconds, then check the level and top up if needed. It does sound like air in the system somewhere.:)
     
  7. beezanick

    beezanick Senior Member

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    Shouldnt the coolant be blead by removing the temp sender?
     
  8. MJ

    MJ Public transport abuser

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    most of the vw group systems can sufficiently bleed themselves, if not then there will be a bleed screw at the appropriate point.

    Never personally had to remove one to bleed a coolant system TBH.
     
  9. FRich

    FRich Guest

    Ok, done a week of driving to work and I'm still loosing coolant... The heater is behaving its self now but every morning I am topping up the coolant which drops between the min and max lines... Thats a lot of coolant to be lost over a 45 mile round trip! I'm fearing head gasket although there's no coolant in the oil and vice versa... What else could it be before I bite the bullet? Changed the water pump so its not that even though it was causing a problem which did lead to me over heating and having steam pour out of the expansion tank (cap changed after this)
     
  10. Copey

    Copey Senior Member

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    Ive had practically the same issue since ive had mine, never been able to work out what the problem was, it looses a little bit of coolant but im toppping mine up every so often, not every day.
     
  11. MJ

    MJ Public transport abuser

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    have it pressure tested to see if the level drops.
     
  12. FRich

    FRich Guest

    is that a common test for a garage? Every time I take it to a garage they say they pressurise it and it doesn't lose any coolant. they'll leave it running for 20 mins and its perfectly fine. They must think I'm making it up lol
     
  13. Seatmann

    Seatmann Rough around the edges

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    Usually when the head gasket starts to go the car sometimes idles a bit rough and the exhaust is fairly white because of steam. You don't always get oil and water mixing, more often it leaks between a cylinder and the water jacket. One of the signs is also the coolant pipes get really hard because of excess pressure. I don't know about your car but on my tdi the coolant temp sender is held in with a clip and some of them can be a bit of a crap fit. I would also check any hoses round the back of the engine for slight corrosion and also check that there isn't an overtightened hose clip. I've seen people cutting the end off the pipe from over tightening them. Just get your fingers underneath any joins and have a bit of a feel. If there's any coolant leaking it will feel kind of greasy/sticky. My mate had this issue on his vauxhall and it was a clip to tight down the back of his engine and the garage missed it somehow. I just took the damaged end off and redone the join and that was that cured.:)
     
  14. FRich

    FRich Guest

    Well I think I've found the problem. Had a lot of pressure left in the coolant system overnight and my coolant has gone from pink to green... Head gasket time! Although I'm worried because when I over heated I waited about 30 mins and topped the coolant up with cold stuff. So I'm scared I've cracked or warpped the head as I doubt my luck is that bad that the water pump and head gasket went at the same time
     

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