Cooling problem. Water pump, thermostat?

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  • k.alle
    S2Forum Maniac
    • Feb 2008
    • 801
    • Country: Sweden

    #1

    Cooling problem. Water pump, thermostat?

    Sorry for a bit lengthy post but I want to include as much relevant info as possible.
    Jump down to 'In short' for a quick read.

    Background:
    This is an issue that has developed progressively.
    When I drove the car to winter storage last year (and the month leading up to that) the engine would overheat on Idle/Cruising/Low RPM.
    If I kept the engine at >3000 rpm in combination with moving car the temperature dropped down to near normal temperatures.
    My first theory was that I knew I had a leakage somewhere and that over time it had created some nasty air locks.

    Actions taken:
    I have recently fixed my leak at water manifold.
    The system is vacuum tested and pressure tested to 1.5 bar for near an hour.
    No vacuum drop and no pressure drop.

    I filled the coolant with this kind of kit:


    If you are unfamiliar on how these types of vacuum fillers work look here:



    Current situation:
    The engine will still overheat.
    My ECU uses the sender on the back of the head and will rise to 110-120 C and climbing if I leave it.
    The cluster gauge sees ~90-95 in these cases climbing upwards and lagging behind the ECU sensor.
    The fan doesn't come on because the temp on the lower end of the rad is cooler.
    There's no heat from the heater matrix.
    Engine bay gets very very hot if I let it sit like this
    It's almost like the water sits stationary in the system.


    In short:
    • System should free of air pockets
    • No leaks
    • Radiator nearly new Behr
    • No aux rad
    • No heat in cabin, matrix hoses cool
    • Thermostat hose cooler than the top
    • Expansion tank is cool
    • Engine gets stinking hot


    Could it be that my water pump impeller has broken down? I think it is plastic.
    Or is it just the thermostat stuck on closed position?

    What brands should I get for these parts?
    Audi S2 -1994 | 480 Hp 650 Nm | FlexFuel | MaxxECU | 3" Stainless | Porsche GT3 Front Brakes
    http://www.garaget.org/?car=52877
  • Tractor Dave
    S2Forum Zealot
    • Dec 2017
    • 5983
    • Country: Wales

    #2
    Start by changing the thermostat.
    When was the cambelt and water pump last changed?
    SKF water pump a good brand but buy direct to avoid counterfeit! They have set up their own website to address this.
    Thermostat is still available from Audi.
    Last edited by Tractor Dave; 9 June 2020, 09:00.
    Nothelle S2 Avant
    Black Ur project
    Silver Rs2 Project gone
    Ocianic Ur project gone
    S2 Coupe project gone
    Urs6 plus project gone

    Comment

    • k.alle
      S2Forum Maniac
      • Feb 2008
      • 801
      • Country: Sweden

      #3
      Cheers Dave.

      Cambelt maybe 2 years ago when I was messing with timing issue, maybe done 10.000 km since.
      Water pump when I built the engine, lets say 3 years ago. Similar milage.

      SKF swedish website does not allow for direct purchase, where are you finding this?
      OK, I'll get the thermostat from Audi then.
      Audi S2 -1994 | 480 Hp 650 Nm | FlexFuel | MaxxECU | 3" Stainless | Porsche GT3 Front Brakes
      http://www.garaget.org/?car=52877

      Comment

      • Tractor Dave
        S2Forum Zealot
        • Dec 2017
        • 5983
        • Country: Wales

        #4
        Cambelt and pump should be good then.
        I use this website
        SKF Automotive delivers precision bearings, driveline systems, and aftermarket parts for passenger vehicles, commercial vehicles, and racing since 1907.
        Nothelle S2 Avant
        Black Ur project
        Silver Rs2 Project gone
        Ocianic Ur project gone
        S2 Coupe project gone
        Urs6 plus project gone

        Comment

        • k.alle
          S2Forum Maniac
          • Feb 2008
          • 801
          • Country: Sweden

          #5
          I see, we don't get that option on the Swedish site.
          Found a reseller local to me so I should be OK anyway.

          I guess autodoc and the likes has big potential on carrying the counterfeit versions?

          [EDIT]
          Local VAG store did not bother answer when I called.
          But I found another local store which carries the Wahler thermostat that should be the same as the Audi part according to this:


          Price is a lot better as well.
          Last edited by k.alle; 9 June 2020, 10:09.
          Audi S2 -1994 | 480 Hp 650 Nm | FlexFuel | MaxxECU | 3" Stainless | Porsche GT3 Front Brakes
          http://www.garaget.org/?car=52877

          Comment

          • Error404
            Super Moderator
            • Mar 2007
            • 19789
            • Country: United Kingdom

            #6
            Half of AUTODOC is fake.
            Panthero Coupé quattro 20vt
            Indigo ABY coupé
            Imola B6 S4 Avant

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            • k.alle
              S2Forum Maniac
              • Feb 2008
              • 801
              • Country: Sweden

              #7
              I suspected as much Alex.

              Good news, a new thermostat solved the issue with overheating.
              Ended up buying it from Audi in the end.

              The "old" one must have been some crap brand I guess since it's only a few years old.

              [EDIT]
              And thank you Tractor Dave for recommending me going for thermostat first.
              Last edited by k.alle; 12 June 2020, 19:40.
              Audi S2 -1994 | 480 Hp 650 Nm | FlexFuel | MaxxECU | 3" Stainless | Porsche GT3 Front Brakes
              http://www.garaget.org/?car=52877

              Comment

              • M_GORDON
                S2Forum Extremist
                • Oct 2008
                • 1295
                • Home: Isle of Man Current: Vatican City State

                #8
                Hi.
                I have similar problem but backwards...

                Recently installed Vidar's 70mm radiator and the temperature is too low.

                The Thermostat is an OE with poor kms but 4 years or more installed on two engines.

                It's possible that is partially opened? Or maybe from afterun pump watter flows too cold from radiator to engine etc and cool everything?

                Ps. It's true that the Thermostat must be installed on vertical?


                THANKS FOLKS
                photobucket SUCKS
                sigpic

                Comment

                • k.alle
                  S2Forum Maniac
                  • Feb 2008
                  • 801
                  • Country: Sweden

                  #9
                  Originally posted by M_GORDON
                  Hi.
                  I have similar problem but backwards...

                  Recently installed Vidar's 70mm radiator and the temperature is too low.

                  The Thermostat is an OE with poor kms but 4 years or more installed on two engines.

                  It's possible that is partially opened? Or maybe from afterun pump watter flows too cold from radiator to engine etc and cool everything?

                  Ps. It's true that the Thermostat must be installed on vertical?


                  THANKS FOLKS
                  For me it sounds like a classic thermostat issue.
                  I don't think your system is too cool in that sense, the thermostat should take car of that for you keeping it at ~90C.

                  This of course if the rest of your cooling system is good, leak & air pocket free.
                  Audi S2 -1994 | 480 Hp 650 Nm | FlexFuel | MaxxECU | 3" Stainless | Porsche GT3 Front Brakes
                  http://www.garaget.org/?car=52877

                  Comment

                  • Tractor Dave
                    S2Forum Zealot
                    • Dec 2017
                    • 5983
                    • Country: Wales

                    #10
                    Originally posted by k.alle
                    I suspected as much Alex.

                    Good news, a new thermostat solved the issue with overheating.
                    Ended up buying it from Audi in the end.

                    The "old" one must have been some crap brand I guess since it's only a few years old.

                    [EDIT]
                    And thank you Tractor Dave for recommending me going for thermostat first.
                    Well done. You are welcome. Happy to help.
                    Nothelle S2 Avant
                    Black Ur project
                    Silver Rs2 Project gone
                    Ocianic Ur project gone
                    S2 Coupe project gone
                    Urs6 plus project gone

                    Comment

                    • M_GORDON
                      S2Forum Extremist
                      • Oct 2008
                      • 1295
                      • Home: Isle of Man Current: Vatican City State

                      #11
                      Originally posted by k.alle

                      For me it sounds like a classic thermostat issue.
                      I don't think your system is too cool in that sense, the thermostat should take car of that for you keeping it at ~90C.

                      This of course if the rest of your cooling system is good, leak & air pocket free.
                      Hi.
                      the temp is around 89°C but goes down to 75 or less on highway

                      It's true the correct position of the Thermostat? Horizontal position of it?

                      Thanks a lot
                      photobucket SUCKS
                      sigpic

                      Comment

                      • k.alle
                        S2Forum Maniac
                        • Feb 2008
                        • 801
                        • Country: Sweden

                        #12
                        OK, could be thermostat.

                        I mounted it vertical, not horizontal.
                        Audi S2 -1994 | 480 Hp 650 Nm | FlexFuel | MaxxECU | 3" Stainless | Porsche GT3 Front Brakes
                        http://www.garaget.org/?car=52877

                        Comment

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