About a month ago I took my '96 Megane 1.4 Paris into the local garage as it was overheating and spewing coolant out of the expansion tank.
After having the car for a couple of days, they replaced the thermostat, but that didnt stop the coolant coming out of the bottle, so they replaced the expansion bottle cap, and that seemed to do the trip.
Now, 5 weeks later, just as I was stopping looking at the temperature gauge, it overheats again. I pop the bonnet and coolant is being ejected out of the expansion bottle again.
I take it into the garage again. They bleed the system, and again, it seems to be ok. Now, I've driven it only a couple of times since, and done only about 3 miles, and I decide to just check the expansion bottle when I get home from work. There is coolant coming out of the bottle again.. only very slowly but I know if I had just done 1 more mile then it would have overheated again, and it would be gushing out of the tank.
The guys at the garage advised on my last visit that they didn't 'think' the head gasket was blown. Surely there would be more of a sign if it had? It seems to drive perfectly well, just not circulating the coolant. Its not losing coolant anywhere apart from out of the expansion tank, as if the pressure is too high and the water is escaping out of the weakest point, ie the bottle top?
Just wondering if anyone had experience of this, and what may be causing it so I can point the local garage at anything they might want to check?
Appreciate any suggestions.
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It does sound like head gasket failure I am afraid, the cylinder pressure pressurises the coolant.
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Check the coolant for any signs of oil contamination and vice versa, that would point further to HG failure, but it sounds as if the head gasket has blown between a cylinder(s) and the coolant passages. This would cause combustion gases to enter the cooling system, thus pressurising it and causing the coolant to be forced out. This can be further confirmed by means of a 'sniffer test' which would detect combustion gases in the coolant.
Only way out I'm afraid would be a replacement head gasket. Worth a trip round a few garages to get an idea of cost. I wouldn't drive this car until the problem is sorted as overheating will run the risk of damaging the head completely.
Unlucky...
Martin
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If thats true then its my worst nightmare come true. I was hoping to Part Ex soon on a new car :(
Are there any other indications of a a gasket failure. I've looked for oil in the water, mayo in the filler/dipstick, but nothing is there. The car itself seems to run ok when its not overheated, and it ran fine for 5 weeks after the previous time.
Could there be a blockage somwhere in the system stopping the coolant from flowing normally?
Sorry if it seems im clutching at straws but I'd rather fix it and get a few hundred quid on the part ex than the £25 from the scrapper.
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A car like that would go straight to auction if you part-exed it. If you were sneaky you'd make sure there was no sign of coolant leakage when you dropped it off and drive off in your new car pronto.
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This is a long shot, but I had the same problem on our 97 Fiesta Zetec which turned out to be linked to the heater valve. If the heater was on hot it was fine, if on cold it would overheat (and the coolant would boil over in the tank).
Again suspected the head gasket, but no sign whatsoever. Had a compression test and cooling system pressure test done which both came back fine. Did all the usual stuff (thermostat, water pump, radiator flush etc) and no joy. Swapped the heater valve out and it's been fine for 2,000 miles now. The bypass on the heater valve was not working properly when the heater was in the closed position.
Have no idea if the Megane heater works the same way, but does your heater setting make any difference?
Cheers
DP
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As Martin1981 suggests get a garage to 'sniff' around the coolant tank with their emissions tester, this will tell very quickly & cheaply whether the head gasket has gone or not; it certainly sounds like it.
FWIW my last Cavalier was still returning 40+ mpg & performing normally , even when the head gasket had gone and it was using a pint of water a day!
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