306 XSi too hot after fixing misfire problem

Discussion in 'Peugeot 306' started by jkn, Oct 30, 2007.

  1. jkn

    jkn Guest

    Hi all
    My '95 306 XSi has had a misfire/juddering acceleration problem
    for more months than I'd care to admit to - from reading this
    newsgroup & elsewhere I had been chasing down air leaks and other
    possibles as causes of the problem. However after a casual comment
    from a local garage I realised that the HT leads were sparking,
    replaced the leads and - Bingo! My misfire is gone.

    I report this here partly so others can know about this as a possible
    caused. And I'm embarrassed for not trying the simpler things first.

    When the car was misfiring the engine would get hotter than I'd like -
    up to around 110 or higher in town traffic - but I was able to keep
    the temperature down by keeping in low gear & the revs outside the
    misfire range. After I had the HT problem diagnosed I also replaced
    the spark plugs, and reset the ECU, guessing that the misfire would
    have 'miscalibrated' the ECU.

    Now though, the engine is consistently running hot - 110 or greater,
    and a couple of times it's hit the temperature at which the STOP light
    comes on ;-(. My oil & water levels are good good and the engine seems
    to be running well.

    I'm guessing that fixing the misfire problem may be showing up this
    temperature problem, or that they may be related. I was hoping that my
    new sparkplugs & reset ECU approach would work, & now it hasn't I'm
    wondering what to do next. Any suggestions?

    jon N
    jkn, Oct 30, 2007
  2. jkn

    Gary G Jones Guest

    not wanting to ask the obvious but is the electric cooling fan cutting in
    when it should,
    Only ask this as I had a Vauxhall many moons ago and if you watched the
    temperature gauge then as soon as you saw it pass a certain point you new
    the fan would cut in, plus it had a battery gauge so you could see the power
    drain. Occasionally the fan would not cut in and it was usually a dirty
    connections, once it was the relay that had failed
    Anyway, its a fine line between the fan coming on and the engine

    Gary G Jones, Oct 30, 2007
  3. jkn

    jkn Guest

    Hi Gary


    AFAIK the fan is cutting in - at least it's can hear it running for a
    few minutes when I switch the engine off!

    I'll see if I can hear it cutting in in normal operation.

    Thanks for your thoughts.

    jkn, Oct 31, 2007

  4. It hasn't got two fans has it and only one working? Seems to be quite a
    common Pug problem to do with relays.
    Keith Willcocks, Oct 31, 2007
  5. jkn

    jkn Guest

    Hi Keith
    seems to have one fan.

    Some more experiments: I unclipped the connector from the radiator
    thermostatic switch and shorted it; the fan started up fine. And it
    runs for a few minutes after the engine has stopped. I've heard it
    running whilst driving but haven't determined at what temperature it
    cuts in.

    I've just driven around 5miles/10 minutes (A roads mostly) from
    'almost cold'. The temperature gauge has just hit 110. From feeling
    around the radiator, the Right Hand Side (looking from the front) of
    the radiator, including the hose, is pretty hot. The middle and LHS of
    the radiator are cool.

    I'm wondering if the thermostat is b*ggered?

    jon N
    jkn, Nov 1, 2007

  6. Does sound as if it is stuck in the closed position or not opening early
    enough. I only know one way to test that. It involves removing it, a
    cooker, a large saucepan and a cooks thermometer. The rest you can probably
    work out for yourself. On my old Princess (the last time I had occasion
    to test one) it was supposed to open as the water approached boiling,
    bearing in mind it boils at a lower temperature than in the car because it
    is not pressurised.

    If the 306 is anything like the 406 watch out on refilling. On the 406,
    because the water circulates higher than the filler cap, you have to
    artificially raise the filling position. I believe plastic lemonade
    bottles with their bottoms removed can be used provided that a good seal is
    maintained where it enters the filler neck. You could, of course, also
    stand the car on its tail ;o)
    Keith Willcocks, Nov 1, 2007
  7. jkn

    Gary G Jones Guest

    sounds like your thermostat is stuck closed as suggested. You could test it
    using boiling water in a sauce pan , but to be honest I would just replace
    it with a new one.
    It could also be well worth it while you have the radiator pipes off to
    blast a hose pipe through it from on side to the other and see if any crud
    comes out of it, could find that half of the radiator is blocked with crud .
    Best of luck, let us all know how you get on.
    Gary G Jones, Nov 1, 2007
  8. jkn

    jkn Guest

    Hi Guys
    Thanks for the suggestions. I'm trying to locate a new thermostat
    at the moment. Unfortunately the one for the 2L XSi seems to be hard
    to come by ...

    I had a look at the thermostat housing. On this model at least, on top
    of the housing there's a small unscrewable knob, very like the top of
    a toothpaste tube (though black plastic obviously). Any clues what
    this is for?

    Jon N
    jkn, Nov 2, 2007
  9. jkn

    Bob Minchin Guest

    Bleeding the cooling system
    Bob Minchin, Nov 2, 2007
  10. jkn

    jkn Guest

    Hi Bob
    Thanks - I was guessing this might be so, & now I've found the right
    pages in the Haynes manual ;-)

    I'm actually wondering if the problem has been an airlock in the
    cooling system all along. Things have been significantly better after
    I loosened and refitted the small 'toothpaste' knob. I also note that
    the hose from the thermostat gets 'properly hot', indicating I think
    that the thermostat is operating.

    Anyway, since a new thermostat is only 12 quid or so, I think I'll get
    one and drain & flush the whole system anyway. I'll let you know how I
    get on.

    jon N
    jkn, Nov 5, 2007
  11. jkn

    Chrs Guest

    If your in the u.k dont forget the anti freeze.you might think i do it
    later but you always forget and by then its too late.
    Chrs, Nov 8, 2007
  12. jkn


    Aug 12, 2013
    Likes Received:
    I know it's 7 years ago since this thread but did you ever sort this problem on the pug306 xsi 2L? I have exactly the same car with the same problem. When the car gets hot, and only then, it gets really unhappy - idling rough, misfires etc. diagnostic light comes on and a funny smell comes through the heaters in the car; like unburnt petrol. Have checked the coolant system, flushed airlocks, replaced thermostat, checked fans - both kick in to cool overheating, replaced sparks, new exhaust sytstem etc but still cant pin the problem down. Wondered whether the HT leads might be worth checking - did this help? Cheers, Luke
    Luke733, Aug 12, 2013
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