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2007 Corsa 1.0 Life Bizarre overheating problem.

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  • [Corsa D] 2007 Corsa 1.0 Life Bizarre overheating problem.

    Hi all, i took this Corsa in of a young girl that was having a strange overheating problem, i'll list below whats happened and what is happening. its a 2007 1.0 with 96k on the clock.

    You can drive around all day at low speeds and even in traffic and the temp gauge (in the hidden menu) stays between 85-91 degrees C, take it onto the motorway and within a couple of minutes at 70 mph the temp rises rapidly to 120 degrees. It cut out on her a couple of times as the overheating safe mode kicked in.

    The car had its water pump,timing chain and thermostat replaced recently.

    There is no oil/water cross contamination and the heater stays toastie warm, it had a "sniff test" on the coolant and found no hydrocarbons in the coolant so we ruled out that the headgasket was failing. There is also no back pressure in the expansion tank and the hoses are soft and not under pressure

    It did seem to have air in the system after the work was done so it was bled up to remove any air and it was bled from the secret bleed screw on the top left of the radiator.

    So off it went again back out onto the road, drove around great for days at low speeds until it hit the motorway and it overheated again.

    I've just been out in it for an hour and found it fine for 30 mins until i tried the motorway and it started to overheat again, i coasted off at the next slip road and noticed it was cooling down rapidly, then, on the 3 or 4 mile drive back, the temperature fluctuated rapidly between 85-120 degrees?

    Could it actually be a dodgy temp sensor sending strange signals to the ecu? as I've never seen a temp rise and fall and visa versa as quick. Anybody else experienced anything similar?

    Its getting very close to head banging time!

  • #2
    If its actually getting up to 120 on the temp. You could try touching the top hose very carefully and feel if its actually getting up to that temperature. And there would be an distitive smell from the engine bay at that temperature. I wonder if it's the new thermostat causing a restriction on the flow of the coolant when it's at speed . What about the small hose from the top of the water pump that goes to the throttle body. is this blocked.
    Last edited by Restorer; 20-07-2019, 08:14 AM.

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    • #3
      It could be a faulty sensor but it seems strange it 'knows' to read differently only at motorway speeds. But you could check the alternator output/rectification. If its giving out a higher voltage at higher revs could this affect the temperature sensor, which may be reading electrical resistance? A long shot

      Sounds more likely there is a blockage somewhere , or despite your best efforts there is still an airlock in the system. (corsas are particularly vulnerable to this. ) This could leave an area that is not getting enough coolant and gets very hot , but only locally near the sensor. When engine speed drops and enough cooler liquid from elsewhere in the system manages to get through , things cool rapidly.

      With a very bad coolant loss on older cars you could sometimes get the phenomenon where the temperature gauge rises , then suddenly drops, almost to nil. This was due to there not enough coolant in the system to actually reach the temperature sensor at all which was effectively measuring air temperature! Seizure was imminent. I'm not saying this is what is likely with this car .

      Were the water pump and thermostat changed in an attempt to cure this problem, or did the problem start only after they were changed?

      As a first step I personally would drain the coolant and start again. Refilling it VERY slowly to minimise the chances of an air lock. Almost dribbling it in . And making sure the valve to the heater is open.
      Last edited by Bugman; 20-07-2019, 07:32 AM.

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      • #4
        Ok thank you for your replies, i'll check the hose to the throttle body and i'm also going to change the temp sensor as thats that eliminated and out of the way, i was also thinking about a blockage somewhere.

        She had the pump changed as it started leaking,so whilst it was off the chain was also replaced. She did fill it with leak repair and k seal to try and stop the leak before the pump was changed, i cleaned the cooling system out to remove all the residue but i did think this could be blocking up somewhere.

        I must admit that when it was showing 120 degrees it didn't feel or smell like 120 degrees.

        I'll change the sensor and bleed it up again this week, then i'll report back.

        thanks again.

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        • #5

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          • #6
            Ok. a bit of an update, fitted the radiator and temp sensor, bled the system up checked all the smaller pipework for blockages, everything is flowing nicely, drove it 15 miles to work, the first 12 miles was on normal roads and everything was perfect, i hit a stretch of dual carriageway for a couple of miles and all was looking good until i turned off to do the last mile to work and it overheated again!! i'm bamboozled now, i just wonder if the head gasket is in the very early stages of failing as i left the car to cool for 5 hours at work then when i released the pressure cap on the expansion tank there was quite a bit of pressure released.

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            • #7

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              • #8
                Originally posted by walksall View Post
                Cheers, thank you for the advice, i've just taken it down the motorway and took it up to 75 mph and the temp stayed settled at 90 degrees, i came off the motorway and returned home and it stayed the same, it actually made it there and back, however one thing i noticed was coolant leaking out of the little overflow pipe on the expansion tank when i left it running after the drive, could the cap be the problem after all?

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                • #9
                  I would suggest that you keep an eye on the coolant level, maybe even using a felt tipped pen to make a mark on the reservoir at the 'settled' level.

                  There is a possibility that you may have topped up the coolant to too high a level and what you have seen dripping from the overflow is excess coolant.
                  Obviously, if the level falls below your pen line, then there is still a problem, but if it is just finding its 'natural' level, then the cap is probably OK - That doesn't explain the lack of pressure in the system though, which would be caused either by a leak, or a faulty cap.

                  Another possibility for overheating (though NOT for lack of system pressure) could be that the airways through the radiator are blocked or partially blocked, this would particularly make itself known in the very hot weather that we have had.

                  If the system still lacks pressure, the small cost of a new cap might be a good investment, at the very least, if there are any leaks, they will be more likely to show up with pressure in the system.

                  Regards

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                  • #10
                    Originally posted by walksall View Post
                    I would suggest that you keep an eye on the coolant level, maybe even using a felt tipped pen to make a mark on the reservoir at the 'settled' level.

                    There is a possibility that you may have topped up the coolant to too high a level and what you have seen dripping from the overflow is excess coolant.
                    Obviously, if the level falls below your pen line, then there is still a problem, but if it is just finding its 'natural' level, then the cap is probably OK - That doesn't explain the lack of pressure in the system though, which would be caused either by a leak, or a faulty cap.

                    Another possibility for overheating (though NOT for lack of system pressure) could be that the airways through the radiator are blocked or partially blocked, this would particularly make itself known in the very hot weather that we have had.

                    If the system still lacks pressure, the small cost of a new cap might be a good investment, at the very least, if there are any leaks, they will be more likely to show up with pressure in the system.

                    Regards
                    Once again thank you, i value your advice, i have ordered a new cap and will collect it tomorrow. so all in all so far the corsa has had;

                    Water pump
                    thermostat
                    radiator
                    temp sensor
                    sniff test on the coolant came back clear.


                    Fingers crossed the cap could resolve it, when you google faulty rad cap it does give all the faults this corsa has had so far.

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                    • #11
                      I hope that this solves your problem.
                      Do please let us know how things turn out.

                      Regards

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                      • #12
                        Ok here we go again, i put a new rad cap on it, drove it up and down the motorway (10 mile round trip) no problem whatsoever, earlier today it managed a 45 mile trip down the motorway with no problem,now it has just done a 5 mile round trip and it has overheated again as it pulled into the drive and it spat all the coolant out of the overflow pipe.. i'm now totally bamboozled.

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                        • #13
                          Ah. Could it be the expansion bottle thats damaged rather than the cap? .Either distorted and not making a good seal, or cracked. Or thread damage stopping the cap being fully tightened.

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                          • #14
                            A couple of 'might be's' come to mind:

                            There is a chance that the air-ways through the radiator are partially blocked in such a way that, when driving on the M-way, sufficient air is being pushed through the rad to keep the temperature down, but at lower speeds, this might not be the case.
                            The above leads on to another possibility - When the coolant was ejected, did you notice what the temperature gauge was reading? also, had you noticed if the can had cut in?
                            If the temperature was normal and the fan had not cut in, then there is a likelihood that what Bugman suggests, may apply.

                            Another possibility, is that the new thermostat is faulty, remaining closed (or partially closed) when it should be open - You could check this out by removing the thermostat and running without it for a few days to see if the problem persists. If this does 'cure' the problem, do NOT be tempted to leave the 'stat out permanently, but purchase a new good quality one.

                            Once that you have identified and cured the problem, it would be a good idea to replace the coolant, as it could well now be too dilute (unless you have been tipping up with coolant mix rather than with plain water.)
                            A 50/50 mix of coolant with water is to be recommended, but there are a couple of things to remember:
                            (1) It is difficult to be sure that ALL of the old coolant has been drained out, therefore it is always as well to put the required quantity of neat coolant into the tank and then top up with plain water - this could result in the strength being above the required 50/50, however, this is much to be preferred to having it too weak.
                            (2) Remember that you need to put the coolant or water into the system VERY slowly on these engines, almost dribbling it in; failure to do this will almost certainly result in air-locks. Leaving the heater control on 'Hot' whilst adding coolant also helps to prevent air-locks.

                            Regards


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                            • #15
                              Hey well, the underlying problem finally turned up, the head gasket was slowly going, now it has totally gone, time to get the spanners out, i suppose its the only thing left on the engine to change

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