temperature going up and down

[mr_f700]

hy guys when im driving along tha temperature gauge goes up and down constantly between half and 3/4

just wondering if anyone knew y it would do this??

could it be thermostat?

or water pump on the way out?


any ideas thanx guys

[Bennoz]

Could be a number of things. First up, check the basics. Water level, whether it needs a flush, whether it needs more or less coolant. You can test the thermostat by pulling it out & dumping it in boiling water. If it opens its ok, if it stays closed replace it. Maybe even have the system pressure tested. Has the pump been replaced? How many kms has it done?

Check the thermo fans - leave it on idle while looking under the bonnet. Does the passenger side fan turn on when it hits the 3/4 mark? If not, you may have blown the thermo fan fuse.

If all of the above are ok, I'd be checking the ECU engine temp sender unit. The cooling system uses 2 sensors. One is a single wire sensor near the thermostat that tells the gauge what temp the water is, the other is a 2 wire unit that tells the ECU what to do at what temp. Everything from adjusting the air/fuel mixture to when to turn the thermo fans on. It would be the one too look at.

Pic of where its located:



Red arrow is ECU sender unit

[mr-charisma]

thats one tidy lookin' engine bay..

[Bennoz]

poms mate... obssesed with bling.

[mr-charisma]

hehe, no complaints from me .. wish my engine bay looked like that (well, except for the GR Engine )

I take it the second picture is of an Aussie Engine..

[payaya]

poms mate... obssesed with bling.

Ali G!

Is the coolant levels fine???

[khunjeng]

coolant levels - overflow and through the cap
drain and fill + thermostat + new cap
check for blockage in the radiator...pressure test.
then if u still have issues, water pump..