156 1.8TS Overheating

Discussion in 'Alfa Romeo 156' started by Gareth Hill, Dec 5, 2006.

  1. Gareth Hill

    Gareth Hill Guest

    I've recently started having problems with my 156 1.8TS overheating.
    I generally use a local mechanic who I trust and can afford rather than
    the local Alfa dealership, but we are struggling to find the cause for
    the problem. I'm not a mechanic but am hoping we can find a solution
    without resorting to using the dealership!

    The water level in the expansion tank is fine, as is the oil level when
    checking the dipstick. When the car reaches the 'normal' running
    temperature between 70-90, the gauge drops down again before rising,
    leading me to think the thermostat is opening. I can moderate the heat
    by turning the heater on and the pipe leading into the expansion tank
    gets warm, which makes me think the water pump is working.

    When the car reaches extreme temperatures (it reached approx. 110 when
    I first realised the problem) the radiator fan is not kicking in. Also
    the OBD (engine management) light was on for a short period after we
    recently changed the cambelt, but the light went off after a week (is
    this related?).

    These clues point towards it being something sensor or OBD related...?
    Anyone any ideas what we should try next?

    I've also had suggestions that it could be an air-lock, does this sound
    feasible and how would I go about releasing one??
     
    Gareth Hill, Dec 5, 2006
    #1
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  2. Gareth Hill

    John, UK. Guest

    Possibe. Has the water been drained lately? after draining radiator,
    the inside car temp [usually on most makes of cars] should be set to
    hot before refilling.
    I presume you have checked the front of the radiator for rubbish,
    paper, plastic bags ect.?
    Hope this is of some help.
    John,UK.
     
    John, UK., Dec 5, 2006
    #2
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  3. Gareth Hill

    alfistagj Guest

    Sounds like the thermostatic switch that engages the electric fan is
    defective, or the fan itself.
    Simple way to check the fan is to disconnect the wires at the switch in the
    radiator and connect them (be sure to switch the ignition "on")
    If the fan starts, it's o.k.
    Then I'm quite sure it's the switch which you can check if you have a
    resistant measuring device; when the coolant reaches 90dgr or so, the switch
    should operate.
    Easy replacement job.
     
    alfistagj, Dec 5, 2006
    #3
  4. Gareth Hill

    Gareth Hill Guest

    Thanks for the replies - I will check the fan switch.
    I know it is a problem that the fan is not coming on when it is getting
    too hot, but I would have thought there must be some other problem
    because the fan did not used to come on before unless stuck in traffic
    and a really hot day. You knew when the fan was running because it was
    really loud. Something else as well as having no fan must be causing it
    to get hot as the fan rarely used to come on even when it was working?
     
    Gareth Hill, Dec 5, 2006
    #4
  5. Gareth Hill

    Graham2 Guest

    It could be that the hot water is not circulating as far as the radiator, so
    the switch will not 'switch' and turn the fan on. Either an airlock, or
    thermostat could possibly cause this. Try squeezing the pipes from the
    engine to the rad and see if you can feel hotter water flowing in the pipe.

    Graham
     
    Graham2, Dec 5, 2006
    #5
  6. Gareth Hill

    Gareth Hill Guest

    I've finally got round to working on this problem some more because of
    the dark nights and have just been controlling the temp manually with
    the cabin heaters!

    I've checked the OBD for errors which was ok, checked the pipes from
    the engine to the radiator and can feel the hot water flowing through
    and replaced the resistor on the fan which did not fix the problem.

    I am looking to test the fan switch manually now as alfistagj suggested
    but non entirely sure how to do this - could anyone give me some
    instructions on how to do this, bearing in mind I'm a novice when it
    comes to electrics?
     
    Gareth Hill, Jan 8, 2007
    #6
  7. Gareth Hill

    di9it8 Guest

    Is the fan relay working?
    If you run the car stationary, until the fan should start, if it does
    the relay is ok
    I would then look to see if it is a faulty thermostat or problems with
    the water circulating
     
    di9it8, Jan 13, 2007
    #7
  8. Gareth Hill

    Gareth Hill Guest

    Thanks for your reply. I've just changed the fan relay and the fan
    still isn't starting when it gets to just below 100 degrees! I'm
    assuming the water is circulating as the pipes to and from the radiator
    are getting hot and I can cool the engine using the cabin heater fan or
    it cools down itself when travelling at speed. The problem all seems to
    relate to the fan not being triggered by some sensor. Does anyone know
    what sensor it is that should switch the fan on and where it is located
    (maybe also what it kind of looks like)? Is the fan controlled by the
    OBD software or is there a hard wired sensor? I've been told that 'hard
    wiring' the fan to the power would be a good method to test that it is
    not just the fan that is broken, but not sure how to go about this?
     
    Gareth Hill, Jan 14, 2007
    #8
  9. Gareth Hill

    SteveH Guest

    Hmmmm - I've had cars that haven't kicked the fan in until they're a
    good few degrees over 100. I think my Cinq. kicked in at around 105 -
    110 degrees.
     
    SteveH, Jan 14, 2007
    #9
  10. Gareth Hill

    Peter Guest

    OK, never having had a 156 I can't say for sure
    BUT...........................................

    You are looking for something called a "Radiator fan switch". Try Google
    images for examples.

    If you have a friendly MotoFactors near to you simply pop in and they will
    check their catalogues and show you a picture of your exact model.

    On Rovers I have known the sensor is at the top/bottom of the radiator
    itself. It was held in by a locking ring that you could simply push in and
    turn and remove.
    On other cars I have come across it may be screwed in.
    Look for anything attached to the radiator that has wires attached and you
    could be onto a winner.

    To test the fan itself you will need to apply 12V directly from the battery
    to the fan.

    Good luck
    Peter
     
    Peter, Jan 15, 2007
    #10
  11. Gareth Hill

    Gareth Hill Guest

    Thanks to everyone for their help. I've eventually fixed the problem,
    well I hope so anyway!
    The wire from the OBD/ECU to the fan relay was broken, hence the fan
    was not switching on. The fan now comes on at a slow speed when the
    car is started - is it normal for the fan to be on permenantly with a
    156? Also in traffic the temperature still rises to just under 110 on
    the gauge - again is this typical for a 156 - I am concerned about
    leaving the engine running for longer/or in heavier traffic to find
    out if it continues to rise!
     
    Gareth Hill, Mar 2, 2007
    #11
  12. Gareth Hill

    Catman Guest

    Well mine doesn't
    Well, stand it on the drive and run it. Wait until the fan kicks in high
    speed and wait some more. Either the temp will drop, or the overheat
    light will come on. If the latter, turn it off quickly.

    It'll probably be OK though.



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    Catman, Mar 2, 2007
    #12
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