Coolant Issues! HELP ME!!!! - SOLVED!!!!

[stew]

Ok been having problems for the last 2 months or so. My radiator was leaking slightly, so i chucked some "radweld" in! Job done!

The coolant temp gauge then started playing up, going up and down every 2minutes or so when driving at steady speed on the motorway.

It has done this ever since!

So far i have changed....

1)Thermostat (my first thought that the thermostat was sticking!)
2)Header Tank (Old one got melted by my bonnet release cable - long story!)
3)Radiator - Old one was ****ed - Done today!
4)Coolant Temp Sensor - Done today!
5)Full coolant flush and bleed X 4 (over the past 2 months)

Ive been told its the CTS, airlocks etc.

So today ive finished replacing everything i can think of, and it still does it!

Any ideas?

Fecking pissing off!

Only think i can think of is the CTS wiring may be loose/****ed somehow!

[Lunner]

First big mistake

DON'T USE RADWELD....EVER!

[MatBrown]

As lunner said, avoid radweld like the plague.

Is the pipe going from the header tank to the stat housing clear?



Mat.

[MAXIBOY]

try flushing the cooling system out with a pressure hose. rad weld can do nasty things to the coolent water ways. whilst working at volkswagen had to scrap a golf engine block due to over use of rad weld.

[stew]

All pipes seem to be clear!

I ran a hose thru everything, and allowed it to build up some pressure!

Really is strange. Its like the temp is going up, then dropping again. To set markers each time!

To me it sounds like a thermstat problem, but ive changed that and still no use!

[MAXIBOY]

nothing to do with the melting wires behind the dash. otherwise just run up from cold ,check the thermostat opens top hose get warm and the fan cuts in. if all working fine you prob have an eletrical prob or faulty temp sender. there are two or three on these. one for the gauge one for the ecu and one for the fan i think.

[stew]

mmm. stat opens fine, otherwise it would overheat.

replaced the gauge temp sensor (brown), the ecu one it white and the fan one is on the radiator itself.

fan cuts in fine. engine runs fine, just this temp gauge is pissing me off. mite investigate the wiring on the temp sensor.

everything is fine behind the dashbaord mate!

[BRUN]

where does it go up and down to ?

[stew]

between 1/3 and 2/3.

basically hovers around normal operating temp, just goes up and down all the time. not a steady level.

i know the temp will change evry so often, but it does it far too often on mine, and never used to!

[BRUN]

mine goes up and down a lot mate since putting a new OE stat in, from the same points as yours