my 340 1.4 problem..

[chunkybond]

right

once my 340 has warmed up and Im driving the engine temperature needle stays solid at about half (warm engine: no probs)
but when Im stood in traffic, the engine temperature rises sharply and only decreases when I start driving out of traffic.
Im not mechanically minded myself, and any help at all would be appreciated..

[trabitom99]

I'd guess the thermostat would be the first thing to check (is warm water being diverted to the radiator?). Then the radiator itself, is it still the first one fitted? If so, chances are it's furred up inside, reducing surface area and thus the amount of water which can be cooled ...

Tom

[chunkybond]

How would I check these things then/what should I look out for?

[trabitom99]

If the thermostat is completely stuck on closed, the radiator, and the hoses leading to the radiator will be cold. It could of course just be "sticky" and not be opening entirely, to check that, you need to remove it put it a saucepan with some water and a thermometer and and slowly bring it to boiling temperature. At somewhere around 90°C it should open.

A bit difficult to check the insides of the radiator really, you could try back-flushing it with a hose after having added some radiator cleaning stuff (I forget what the name of it is) but if you're going to that kind of trouble you might as well change the radiator for a new one, they can be had from the bay quite cheaply. It's not hard, just grab a Haynes and follow the steps.

[filthyjohn]

Does the electric fan come on when the gauge reaches about 3/4?

[chunkybond]

yeah it does, and then it cools off again...

the temp light has never come on though, because theres always been a way i can jump out of the traffic and 'air cool' the car

[trabitom99]

the temp light has never come on though,

it's still winter mind May be another story when it starts getting warmer ...

[chunkybond]

the temp light has never come on though,

it's still winter mind May be another story when it starts getting warmer ...

exactly.
wanted to ask the experts before london warmed up!