Radiator problem

[1998GTS]

Hi all.

I just noticed in the last few days when driving the temp gauge goes up over half when sitting at the traffic lights.When driving on the open road it sits between half and quarter.I got home to today and had a look under the bonnet to find that water from the radiator was going back into my reserve bottle,and once that was full it would flow out the over flow hose.Once it cooled down the water in the reserve would all go back into the radiator.I find this VERY odd.Have i got a blockage or something!!!

Please help Thanks Craig

[levymetal]

when it cools down, how much is it sucking back from the overflow bottle? the level in the overflow will rise when the motor gets hot and falls when the motor gets cold but it shouldn't empty the overflow. if this is happening then you probably have a dodgy radiator cap that isn't holding pressure (thus letting more coolant into the overflow than it should when hot). new radiator cap, fill overflow to correct level and see how you go from there

[BoNeZ-01]

My VS does the same thing, constantly runs around town on about 1/2 temp, the single radiator fan(I only have one fan..? :S) doesn't cut in until it's a micky over 1/2 on the gauge, then by the time the fan cuts off, it's sitting between 1/4 and 1/2.
I read in one of these forums there are different coolant temp sensors, not the one for your dash gauge, the one for the fan.
One has a black connector, one has white, and apparently the white cuts in sooner, at a lower temp?
Might be worth a try, thinking of trying it myself.
Make sure your radiator has no blocks, also check rad cap and thermostat are in good nick and working correctly, if in doubt, they are a cheap replacement.
There is a simple check for your fan too, if you are concerned about weather it's working properly.

[1998GTS]

when it cools down, how much is it sucking back from the overflow bottle? the level in the overflow will rise when the motor gets hot and falls when the motor gets cold but it shouldn't empty the overflow. if this is happening then you probably have a dodgy radiator cap that isn't holding pressure (thus letting more coolant into the overflow than it should when hot). new radiator cap, fill overflow to correct level and see how you go from there

Ok.When it's cold there's no water it the overflow tank,but the radiator is full.After i take it for a run the overflow tank is full.then like i say drains in back into the radiator.Like you say,sounds like a new radiator cap.

[levymetal]

yeah well give that a shot and see how you go! if it's not holding pressure then it can also cause temperature issues so you might be killing 2 birds with 1 stone