You Mechanic types ,any idea what this could be ?

jane2rose, Sep 6, 8:28pm
ok so my car is overheating ,then when i stop it dumps alot of water,but then when I check the radiator and overflow the radiator is still full and only minimal loss (no where near the amount dumped)from the overflow tank.

flitt, Sep 6, 8:41pm
Possibly: a leak in coolant system *or* leak in core plugs *or* fault with radiator cap *or* cylinder head gasket leaking.

jane2rose, Sep 6, 8:44pm
oh right then .its an old car 1985 holden barina ,but has done only 80.000 kms.

splinter67, Sep 6, 8:44pm
What type of car is it Sounds like a air lock to me

jane2rose, Sep 6, 8:44pm
cylinder head gasket .thats a big one ae (problem and $ wise)

jane2rose, Sep 6, 8:45pm
the thing is it did it just the once about 2 months ago ,then all was fine and dandy again ,but has done it twice this week now.

jane2rose, Sep 6, 8:48pm
thought it was like a blockage that was then blown out (sorry if I sound like no idea) I have been able to fix simple logical problems with my car before but not sure on this one.also the first time it happened I ran the car for a bit and noticed the fan at the back of the radiator seemed to take a while to kick in and mabey not working as it should .

budgel, Sep 6, 8:55pm
If you suspect a head gasket get a test done for combustion gases in the radiator.

If it is not that, take the thermostat out and see if the overheating disappears as it may be an intermittent thermostat problem. Make sure radiator cap is the correct one and in good nick.

jane2rose, Sep 6, 9:19pm
intermittent thermostat problem sounds mabey right .does the automatic choke sticking occasionally and revs becoming too high tie in with this also ,doesn't happen all the time but .The radiator cap is correct and sound (as far as I can tell)

NZTools, Sep 6, 10:18pm
Choke staying on and revs to high says you have air in your cooling system.
That may be caused by a blown head gasket, a water leak, or an ir lock. (which happens when the cooling system isnt filled and bled correctly.

jenny188, Sep 6, 10:22pm
2 issues here. The volume of water expands as it circulates, pumping infuses air into the water so it takes up more room, hence the overflow or expansion tank, in the first place. Secondly only what goes in can come out. Cars can't make water (in bulk). Don't worry about the excess as its currently under Waitangi Tribunal clam and is bound to shortly be taken off you and given to some other persons.

xs1100, Sep 7, 9:04am
i would replace the cap anyway a visual inspection wont tell you if its holding pressure also drive with the heater on hot until the temperature heats up could be a air lock

teamgjt, Sep 7, 9:24am
to quote mater off cars movie (thats funny right there)

michelle322, Sep 8, 3:53am
runmotor till gets hot while stationary in driveway and keep an eye on temp and see if fan starts,if it doesn't you need a new sensor for your fan.thats all i needed for the same symptoms as you said.

luigi21, Sep 10, 5:33am
are You sure its not condensation from the Aircon.

strobo, Sep 10, 6:13am
The overflow tank will replenish the radiator level that is why you notice the drop more so in the overflow header tank.than the radiator.(thermo syphon system)) & the leak you notice especially when motor is not running , kinda makes methinks the waterpump , pee hole leak off. some dont leak to the same degree whilst motor is running. i wont suggest how to test the water pump , for good safety reasons , but as saidlool at all the clues & where a leak may come from. stuffed if i know what the airlocks saga means! in relation to a leak.gota be leaking some where.

strobo, Sep 10, 6:13am
The overflow tank will replenish the radiator level that is why you notice the drop more so in the overflow header tank.than the radiator.(thermo syphon system)) & the leak you notice especially when motor is not running , kinda makes methinks the waterpump , pee hole leak off. some dont leak to the same degree whilst motor is running. i wont suggest how to test the water pump , for good safety reasons , but as saidlool at all the clues & where a leak may come from. stuffed if i know what the airlocks saga in post abovemeans! in relation to a leak.gota be leaking some where.have a good look for it, not clear from your post if the overflow tank is blowing out steam any! how exactly is it "dumping water" this would be more of a clue in getting more accurate .

kazbanz, Sep 10, 7:06am
Ahh um er- I HOPE a silly question.--Are you filling the radiator and overflow tank both to the top!