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Thread: overheating on uphills only!

  1. #1
    leexo's Avatar
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    overheating on uphills only!

    My Astra's (DTI 2.0L Year2000) temperature goes high when driving uphills or when depressing the acceleration pedal very tight when (speeding/"racing")

    I've replaced the Thermostat by a fresh new one as well the the water flange (engine's coolant intake).

    Now it reaches the temperature 90c faster & remains there if the road is straight. but on uphills it overheats & the fan(s) work especially the front one that I see that it works on low speed when the gauge just exceeds the 90c.

    To be on the safe side with the fans I fed them with electricity (+ & -) and checked if their two speeds actually work and they do. So I assume that whenever the computer wants to turn on the high speed or the rare fan it can as it wants.

    I took the radiator out and brought it to a specialist that disassembled it from the side and pushed a metallic thread all the way in it's pipes and extracted brown "junk" of calcium and what seemed to me as mud from all the pipes of the radiator (especially the lower ones). He did brilliant job & built the radiator again & tested it for any leak. I got the radiator fresh & clean, washed it again with water hose & made sure no brown water comes from it and installed it back in it's place.

    Now it runs on clean water & the water doesn't become brown like before.
    But the problem persists, only with stiffer/longer uphill drives it overheats above 90.

    Otherwise it seems OK when driving anywhere in the the city or out of it, but just not uphills.

    Can anyone advice on what might be happening here?

    (I've never had such problem before with any car I had)

  2. #2
    paul.spencer's Avatar
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    Hi Alex,

    I read the extra info on the link you provided. Good for you for getting the radiator cleaned out - sounds like it really needed it.

    I reckon that you had better drain that water as soon as possible and put in some 50% antifreeze/coolant in there. And if mixing the 50% yourself from the concentrated coolant, make sure to use water that isn't ""hard" - you know full of calcium magnesium and other minerals. Some people even go so far as to use distilled water.

    The cooling system on my old Astra with the X17DTL engine is completely clean and flushed and has always behaved in a similar way. It maintains 90 degrees or so at 100 km/hr on the flat motorway in 5th gear but can really heat up going up big hills.

    I think it is pretty normal for such significant heating to occur when at higher revs and as long as your rad fan is working it shoul be able to cope with it even if the indicator shows that the temp approaches the red. I remember while on some camping trips in the heat of the summer, driving up long inclined highways and getting stuck in a traffic jam getting rather worried about overheating but the rad fan at high speed is able to reduce the temp.

    In your case with a nice cleaned out radiator, new thermostat, functioning fan and cooling module, plus a proper 50% coolant mix you should be fine. Only other thing you might consider doing is using one of those alkaline chemical cooling system flush products to completely clean out those deposits from the remainder of the cooling system. Just follow the instructions on the bottle and thoroughly flush it out before finally putting in the 50% coolant mix.

    Cheers, Paul

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